To see the other types of publications on this topic, follow the link: Enhanced fluorescence.
Dissertations / Theses on the topic 'Enhanced fluorescence'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Enhanced fluorescence.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Lee, Ming-Tao. "Plasmonic Enhanced Fluorescence using Gold Nanorods." Thesis, Linköping University, Department of Physics, Chemistry and Biology, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-57680.
Full textAbstract:
The aims of this study are to first immobilize positively charged gold nanorods to negatively charged cell culture surfaces. Second, to use polyelectrolytes for controlling the distance between gold nanorods and fluorophores. This is used to optimally determine the distance, of which maximum fluorescence enhancement is achieved, between gold nanorods and fluorophores. In order to approach these aims, we use UV/VIS absorption spectroscopy, fluorescence spectroscopy, atomic force microscopy, and ellipsometry. The results show that we could control the immobilization of gold nanorods on plastic microwell plates and create reproducible polyelectrolyte layers, in order to control the distance between the gold nanorods and fluorophores. In addition, the localized surface plasmon resonance wavelength red shifted as the PELs increased. In conclusion, we found that the maximum fluorescence enhancement of the fluorophores (Cy7) is about 2.3 times at a fluorophores-nanoparticles separation of approximately 9-12 nm. This work contributes some research information towards the design of optical biochip platforms based on plasmon-enhanced fluorescence.
2
Hwang, Kil Dong. "Improved fluorescence-enhanced optical imaging and tomography by enhanced excitation light rejection." [College Station, Tex. : Texas A&M University, 2006. http://hdl.handle.net/1969.1/ETD-TAMU-1062.
Full text
3
Halil, Haithem. "Enhanced fluorescence of dyes in presence of DNA." Thesis, University of Manchester, 2006. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.507953.
Full text
4
Joshi, Amit. "Adaptive finite element methods for fluorescence enhanced optical tomography." Texas A&M University, 2005. http://hdl.handle.net/1969.1/4419.
Full textAbstract:
Fluorescence enhanced optical tomography is a promising molecular imaging
modality which employs a near infrared fluorescent molecule as an imaging agent
and time-dependent measurements of fluorescent light propagation and generation.
In this dissertation a novel fluorescence tomography algorithm is proposed to reconstruct
images of targets contrasted by fluorescence within the tissues from boundary
fluorescence emission measurements. An adaptive finite element based reconstruction
algorithm for high resolution, fluorescence tomography was developed and validated
with non-contact, planewave frequency-domain fluorescence measurements on
a tissue phantom. The image reconstruction problem was posed as an optimization
problem in which the fluorescence optical property map which minimized the
difference between the experimentally observed boundary fluorescence and that predicted
from the diffusion model was sought. A regularized Gauss-Newton algorithm
was derived and dual adaptive meshes were employed for solution of coupled photon
diffusion equations and for updating the fluorescence optical property map in
the tissue phantom. The algorithm was developed in a continuous function space
setting in a mesh independent manner. This allowed the meshes to adapt during
the tomography process to yield high resolution images of fluorescent targets and to accurately simulate the light propagation in tissue phantoms from area-illumination.
Frequency-domain fluorescence data collected at the illumination surface was used
for reconstructing the fluorescence yield distribution in a 512 cm3, tissue phantom
filled with 1% Liposyn solution. Fluorescent targets containing 1 micro-molar Indocyanine
Green solution in 1% Liposyn and were suspended at the depths of up to 2cm
from the illumination surface. Fluorescence measurements at the illumination surface
were acquired by a gain-modulated image intensified CCD camera system outfitted
with holographic band rejection and optical band pass filters. Excitation light at
the phantom surface source was quantified by utilizing cross polarizers. Rayleigh
resolution studies to determine the minimum detectable sepatation of two embedded
fluorescent targets was attempted and in the absence of measurement noise, resolution
down to the transport limit of 1mm was attained. The results of this work
demonstrate the feasibility of high-resolution, molecular tomography in clinic with
rapid non-contact area measurements.
5
Bauch, Martin [Verfasser]. "New enhancement strategies for plasmon-enhanced fluorescence biosensors / Martin Bauch." Mainz : Universitätsbibliothek Mainz, 2015. http://d-nb.info/1068723904/34.
Full text
6
Morrill, Samuel. "Combined Metal-Enhanced Fluorescence-Surface Acoustic Wave (MEF-SAW) Biosensor." Scholar Commons, 2014. https://scholarcommons.usf.edu/etd/5081.
Full textAbstract:
Immunofluorescence assays are capable of both detecting the amount of a protein and the location of the protein within a cell or tissue section. Unfortunately, the traditional technique is not capable of detecting concentrations on the nanoscale. Also, the technique suffers from non-specific attachment, which can cause false-positives, as well as photobleaching when detecting lower concentrations is attempted. There is also a time constraint problem since the technique can take from many hours to a few days in some cases.
In this work, metal-enhanced fluorescence (MEF) is used to lower the detection limit and reduce photobleaching. Unfortunately, MEF also increases the intensity of non-specifically bound proteins (NSBPs). Therefore, a surface acoustic wave (SAW) device is used to remove the more weakly bound NSBPs. Previously, this has been shown on lithium niobate, but it is used with a quartz substrate in this work. The SAW device is also used to cause micro-mixing which speeds the process up significantly.
In this research, it was found that silver nanocubes can lower the detection limit down to below 1 ng/mL. Quartz SAW devices are shown to remove NSBPs at a power of 10 mW applied for five minutes. Micro-mixing is shown to be improved by a factor of six at 10 mW for 10 minutes by saturating the antibody used in this research, which takes 1 hour without micro-mixing. Finally, all three components are combined. In this work, the whole device is used to detect 50 ng/mL. After micro-mixing, the intensity is the same as with MEF, and, after removal, it has been lowered by 7 a.u.
7
Dorcéna, Cassandre Jenny. "Effects of Metallic Nanoalloys on Dye Fluorescence." Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/35057.
Full textAbstract:
Metallic nanoparticles (NPs) are exploited for their ability to interact with organic
compounds and to increase significantly the fluorescence intensity and the photostability
of many fluorescent dye molecules. Metal enhanced fluorescence (MEF) is therefore
widely investigated for biosensing applications. When used in immunoassays, silver
island films (SIFs) could augment the fluorescence intensity of fluorescein by a factor of
seventeen; SIFs were also able to double or triple the emission intensity of cyanine dyes
which are commonly used in (deoxyribonucleic acid) DNA microarrays. The emission
intensity of indocyanine green â widely used as a contrast agent in medical imaging â
was about twenty times higher in the proximity of SIFs.
This enhancement phenomenon - due to the surface plasmon polaritons associated
with the metallic NPs â can be explained by energy transfer from the metal NPs to the
fluorescent dye molecules or by a modified local electromagnetic field experienced by
the fluorophores in the vicinity of metal surfaces.
Our research focused on the optical characterization of colloidal gold-silver alloy
NPs containing different ratios of gold and silver (Au1.00-Ag0.00, Au0.75-Ag0.25, Au0.50-
Ag0.50, and Au0.25-Ag0.75), as well as their interaction with three fluorophores: rose
bengal, rhodamine B, and fluorescein sodium. Depending upon the dye quantum yield
and its concentration in solution, enhancement or quenching of fluorescence was
obtained. Thus, a three to five times increase in fluorescence intensity was observed in a
2.0 mM solution of rose bengal with all nanoalloys, a slight enhancement of fluorescence
(1.2 â 1.6 times) was noticed in a 0.13 mM solution of rhodamine B with all four types of
NPs, and fluorescence quenching occurred in all the fluorescein-NP solutions regardless
of the dye concentration.Master of Science
8
Sahu, Amit K. "Objective assessment of image quality (OAIQ) in fluorescence-enhanced optical imaging." [College Station, Tex. : Texas A&M University, 2006. http://hdl.handle.net/1969.1/ETD-TAMU-1068.
Full text
9
Pang, Jing Sheng. "Engineered nanostructures for metal enhanced fluorescence applications in the near-infrared." Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/43157.
Full textAbstract:
Recent advancements in fabrication techniques allow construction of nanostructures with well-defined features in nanometres scale. Tiny nanostructures that have features below the resolution of optical diffraction limit can now be made in the laboratory. The specific properties of those nanostructures with specific properties made from variety of materials allow us to study and explore many different properties that have never been observed while they are in bulk. One such phenomenon is localised surface plasmon resonance effect, which is exhibited by certain materials when in nanometric size. Their peculiar interaction with light is in such a way that the optical properties such as reflection and transmission deviate from typical characteristics and change according to the material involved and their shapes. Furthermore, this effect could also enhance the electric field in a specific area of the structure. This thesis is motivated by the attractiveness of the tunability of localised surface plasmon resonance and aims at exploring those properties by fabricating multiple types of nanostructures through a low-cost and versatile technique called nanosphere lithography. By improving the technique and combining with other fabrication techniques (such as oxygen plasma etching and argon ion milling), a large variety of nanostructures with hexagonal lattice like as nanocones, nanopencils, and nanofins arrays have been successfully created. Among them, three main types of nanostructure were selected for detailed study: nanotriangle, nanodisc, and nanohole-disc arrays. The distance between the adjacent nanoparticles were changed in those structures and strong interparticle coupling behaviours were observed as the distance between them becomes shorter. Current portable biosensing devices for in vitro studies are limited by the sensitivity limit of the detector, the poor quality of emitters and the size of the devices. In this thesis, the application of localised surface plasmon resonance for near infrared in vitro biosensing is explored. This is achieved through a mechanism called metal enhanced fluorescence. The techniques take advantage of the high electrical field strength and the resonance condition of the plasmon to enable a fluorophore to achieve brighter emission. The greater the resonance and electrical field are, the greater the emission amplification would be. Such effect makes it highly attractive for near infrared in vitro studies, which benefits from high optical penetration of common biology components such as water and lipids, but suffer from poor emission of existing fluorophores. Thus, enhancement of the emission signals through metal enhance fluorescence mechanism is an attractive route to obtain better signal to noise ratio in medical diagnostic, and improve detectability while at the same time reduce the need of a high sensitivity detector which can be costly and large in size. The three chosen nanostructures, i.e. nanotriangular arrays, nanodisc arrays and nanohole-disc arrays have shown marked enhancement in the emission of attached fluorophores up to 83x, 235x, and 411x respectively, making them highly attractive nanostructures for such application.
10
Desai, Darshan B. "Metal Enhanced Fluorescence in CdSe Quantum Dots by Gold Thin Films." Ohio University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1314234319.
Full text
11
Nelson, Jean. "ENHANCED ENVIRONMENTAL DETECTION OF URANYL COMPOUNDS BASED ON LUMINESCENCE CHARACTERIZATION." VCU Scholars Compass, 2009. http://scholarscompass.vcu.edu/etd/2000.
Full textAbstract:
Uranium (U) contamination can be introduced to the environment as a result of mining and manufacturing activities related to nuclear power, detonation of U-containing munitions (DoD), or nuclear weapons production/processing (DOE facilities). In oxidizing environments such as surface soils, U predominantly exists as U(VI), which is highly water soluble and very mobile in soils. U(VI) compounds typically contain the UO22+ group (uranyl compounds). The uniquely structured and long-lived green luminescence (fluorescence) of the uranyl ion (under UV radiation) has been studied and remained a strong topic of interest for two centuries. The presented research is distinct in its objective of improving capabilities for remotely sensing U contamination by understanding what environmental conditions are ideal for detection and need to be taken into consideration. Specific focuses include: 1) the accumulation and fluorescence enhancement of uranyl compounds at soil surfaces using distributed silica gel, and 2) environmental factors capable of influencing the luminescence response, directly or indirectly. In a complex environmental system, matrix effects co-exist from key soil parameters including moisture content (affected by evaporation, temperature and humidity), soil texture, pH, CEC, organic matter and iron content. Chapter 1 is a review of pertinent background information and provides justification for the selected key environmental parameters. Chapter 2 presents empirical investigations related to the fluorescence detection and characterization of uranyl compounds in soil and aqueous samples. An integrative experimental design was employed, testing different soils, generating steady-state fluorescence spectra, and building a comprehensive dataset which was then utilized to simultaneously test three hypotheses: The fluorescence detection of uranyl compounds is dependent upon 1) the key soil parameters, 2) the concentration of U contamination, and 3) time of analysis, specifically following the application of silica gel enhancing material. A variety of statistical approaches were employed, including the development of multiple regression models for predicting both intensity and band structure responses. These statistical models validated the first two listed hypotheses, while the third hypothesis was not supported by this dataset. The combination of inadequate moisture levels and reaction times (≤ 24 hrs) greatly limited the detection of varying levels of U, depending on the soil.
12
Liu, Jing. "Systematic studies of protein immobilization by surface plasmon field-enhanced fluorescence spectroscopy." [S.l.] : [s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=975928848.
Full text
13
Houston, Jessica Perea. "Near infrared optical lymphography for cancer diagnostics." Diss., Texas A&M University, 2005. http://hdl.handle.net/1969.1/4807.
Full textAbstract:
A new molecular imaging modality has been developed to detect and locate positive axillary and sentinel lymph nodes non-invasively in breast cancer patients undergoing lymphoscintigraphy. The modality is based on fluorescent photon detection to locate the presence of indocyanine green (ICG) in the lymph subsequent to peritumoral injection of ICG into the breast. The imaging system consists of a gain-modulated intensified charge-coupled device (ICCD) camera, which captures low-intensity, near-infrared, and frequency-modulated photons. A four-fold âÂÂoptical lymphographyâ study was conducted to (1) examine fluorescence depth penetration and ICCD system accuracy at clinically relevant depths, (2) compare image quality of the ICCD system vs. conventional gamma imaging, (3) measure ICG pharmacokinetics in vivo, and (4) develop a clinical protocol while examining pre-clinical factors such as the outcome of combining ICG with sulfur colloids used in lymphoscintigraphy. The frequency-domain ICCD system was found to precisely detect modulation amplitude, IAC, and phase, ø, at depths up to 9 cm and with IAC accuracy less than 20% and ø less than 2ú using an 80-mW laser incident on phantoms having ranging tissue optical properties. Significant differences in the mean depth of penetration owing to 0.62-ns lifetime and 100-MHz frequency increases were detected. An in vivo optical vs. nuclear image quality comparison demonstrated statistically similar (ñ=0.05) target-to-background ratios for optical (1.4+/-0.3) and nuclear (1.5+/-0.2). Alternatively, resulting image signal-to-noise ratios (SNR) from the ICCD system were greater than that achieved with a conventional gamma camera (pvalue<<0.01). Analysis of SNR versus contrast showed greater sensitivity of optical over nuclear imaging for subcutaneous tumors. In vivo and rapid detection of ICG in the blood-stream of nude mice was accomplished with a home-built avalanche photodiode dynamic fluorescence measurement system. Intensity data upon i.v. injection were regressed with a pharmacokinetic model describing the partitioning of ICG from the blood to the surrounding tissues. ICG blood-clearance was detected approximately 15 min after injection. Lastly, a human subject protocol was written, practiced, and federally approved for the application of optical lymphography. Furthermore, ICG was unaffected when mixed with sulfur colloids thus supporting the feasibility for combining fluorescence imaging with lymphoscintigraphy in breast cancer patients.
14
Ozturk, Tacettin. "The Use Of Gold And Silver Nanoparticles For Surface Enhanced Fluorescence Of Dyes." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612389/index.pdf.
Full textAbstract:
This study focuses on preparing surface enhanced fluorescence (SEF) substrates for use in the enhancement of the emission signal of rhodamine B and fluorescein dyes.
Fluorescence spectroscopy has been widely utilized owing to its high sensitivity. SEF is a process where the interactions of fluorophores with the localized surface plasmons of metal nanoparticles results in fluorescence enhancement, increased photostability and rates of system radiative decay which leads to a decreased lifetime. One of the most important factors of SEF studies is to provide a uniform distance between fluorophore and metal nanoparticle in a controlled mannerotherwise, Fö
rster resonance energy transfer takes place from fluorophore to metal nanoparticle and emission intensity of fluorophore is quenched. The spherical gold and silver nanoparticles were prepared using the well known and straightforward chemical reduction method, in which sodium citrate acted both as a reducing agent and a stabilizer around the formed nanoparticles. Silver and gold were chosen because of their high plasmon field enhancement. Since plasmon field strongly depends on the shape and size of the nanoparticles, the prepared nanoparticles were characterized using absorption spectroscopy and field emission scanning electron microscopy (FE-SEM). Prior to deposition of silver or gold nanoparticles on glass slides, the slides were derivatized by immersing them into an aqueous solution of 3-Aminopropylethoxysilane (APTES). Following derivatization, silver or gold nanoparticles were deposited by immersing the slides into the colloid mixture. Metal nanoparticle coated slides were characterized using absorption spectroscopy and field emission scanning electron microscopy (FE-SEM). Surface enhanced Raman scattering (SERS) measurements were carried out to observe the plasmon efficiency of the deposited nanoparticles. The SERS measurements were repeated for the duration of two weeks in order to check the stability of the plasmon efficiency. In this study, different types of materials (silica, zinc oxide, gold, stearic acid.) were employed as spacers to observe their effects on fluorescence enhancement. Physical vapor deposition (PVD) and Langmuir-Blodgett (LB) film deposition techniques were used for the formation of the spacer within the substrate. Fluorescence enhancement of rhodamine B and fluorescein was observed on the prepared SEF substrates. Obtained enhancement factors indicate that SEF substrates have the potential for sensitivity improvements of fluorescence sensing in many fields.
15
Jennings, Dominique Louise. "Dynamic Contrast-Enhanced Magnetic Resonance Imaging & Fluorescence Microscopy of Tumor Microvascular Permeability." Diss., The University of Arizona, 2008. http://hdl.handle.net/10150/193555.
Full textAbstract:
Microvascular permeability is a pharmacologic indicator of tumor response to therapy, and it is expected that this biomarker will evolve into a clinical surrogate endpoint and be integrated into protocols for determining patient response to antiangiogenic or antivascular therapies. The goal of this research is to develop a method by which microvascular permeability (Ktrans) and vascular volume (vp) as measured by DCE-MRI were directly compared to the same parameters measured by intravital fluorescence microscopy in an MRI-compatible window chamber model. Dynamic contrast enhanced-MRI (DCE-MRI) is a non-invasive, clinically useful imaging approach that has been used extensively to measure active changes in tumor microvascular hemodynamics. However, uncertainties exist in DCE-MRI as it does not interrogate the contrast reagent (CR) itself, but the effect of the CR on tissue water relaxivity. Thus, direct comparison of DCE-MRI with a more quantitative measure would help better define the derived parameters. The combined imaging system was able to obtain both dynamic contrast-enhanced MRI data high spatio-termporal resolution fluorescence data following injection of fluorescent and gadolinium co-labeled albumin. This approach allowed for the cross-validation of vascular permeability data, in relation tumor growth, angiogenesis and response to therapy in both imaging systems.
16
Huang, Shengnan Ph D. Massachusetts Institute of Technology. "Surface plasmon enhanced fluorescence for biological imaging : from visible to short-wave infrared." Thesis, Massachusetts Institute of Technology, 2020. https://hdl.handle.net/1721.1/129028.
Full textAbstract:
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2020Cataloged from student-submitted PDF of thesis.
Includes bibliographical references (pages 139-147).
Fluorescence imaging offers high spatio-temporal resolution, low radiation dosage exposure, and low cost among all the available imaging modalities, for example, magnetic resonance imaging, computerized tomography and positron emission tomography. Imaging probes of high emissivity and photostability are the key to achieving fluorescence imaging with high signal-to-background ratio (SBR). One promising approach to developing highly bright and stable imaging probes is through surface plasmon enhanced fluorescence. In the first part of the thesis, we develop a fluorescent probe with high site-specificity and emission efficiency by exploiting the targeting-specificity of M13 virus and co-assembling plasmonic nanoparticles and visible dye molecules on the viral capsid. Practical factors controlling fluorescence enhancement, such as nanoparticle size and dye-to-nanoparticle distance, are studied in this project. Lastly, the highly fluorescent probe is applied for in vitro staining of E.
coli. The methodology in this work is amendable to developing a wide range of affinity-targeted fluorescent probes using biotemplates. Compared to visible and near infrared spectrum, short-wave infrared (SWIR, 900-1700 nm) spectrum promises high spatial resolution and deep tissue penetration for fluorescence imaging of biological system, owning to low tissue autofluorescence and suppressed tissue scattering at progressively longer wavelengths. In the second part of the thesis, a bright SWIR imaging probe consisting of small SWIR dyes and gold nanorods is developed for in vivo imaging. Fluorescence enhancement is optimized by tuning the dye density on the gold nanorod surface. The SWIR imaging probes are applied for in vivo imaging of ovarian cancer. The effect of targeting modality on intratumor distribution of the imaging probes is studied in two different orthotopic ovarian cancer models.
Lastly, we demonstrate that the plasmon enhanced SWIR imaging probe has great potential for fluorescence imaging-guided surgery by showing its capability to detect submillimeter-sized tumors. Apart from enhancing the SWIR down-conversion emission above, surface plasmon enhanced SWIR up-conversion emission is another promising approach to achieving "autofluorescence-free" imaging with minimal tissue scattering. In the third part of the thesis, we use gold nanorods to enhance the up-conversion emission of small SWIR dyes. The mechanism of surface plasmon enhanced up-conversion emission is studied. The up-conversion fluorescence shows much higher SBR than down-conversion fluorescence in non-scatting biological solution and scatting medium. Lastly, we demonstrate in vivo imaging for the first-time using SWIR up-conversion fluorescence with exceptional image contrast.
by Shengnan Huang.
Ph. D.
Ph.D. Massachusetts Institute of Technology, Department of Materials Science and Engineering
17
Masters, T. A. "Time-resolved fluorescence studies of enhanced green fluorescent protein and the molecular dynamics of 3-Phosphoinositide Dependent Protein Kinase 1." Thesis, University College London (University of London), 2009. http://discovery.ucl.ac.uk/19031/.
Full textAbstract:
Fluorescent proteins (FPs), particularly Enhanced Green Fluorescent Protein (EGFP), are essential tools in the study of intact biological systems. Whilst the photophysics of its progenitor, GFP, have been investigated extensively, far fewer studies of EGFP have been made. In this thesis, a full characterisation of EGFP excited state photophysics by singleand two-photon time-resolved fluorescence lifetime and anisotropy is presented. Furthermore, the two-photon transition tensor, determined by absorption and initial anisotropies, is shown to be dominated by a single element. The two-photon excited state of EGFP was subject to Stimulated Emission Depletion (STED), revealing the stimulated emission cross section, the ground state relaxation time and the time evolution of the higher order distribution moments to which anisotropy is not sensitive. The strong adherence to theoretical Debye diffusion reinforced the conclusions of the two-photon structure model, and showed EGFP to be an excellent molecule for the future development of STED. In addition, these studies provided a sound basis on which to employ single- and two-photon FRET in vivo and in vitro. Cell behaviour is governed by the transduction of molecular signals from the extracellular environment to intracellular compartments. At the centre of the PI 3-kinase signalling pathway is PDK1, a Serine/Threonine kinase, which phosphorylates numerous important downstream targets including Protein Kinase B (PKB). To date however, the regulatory mechanisms governing the behaviour of this protein remain poorly understood. Timeresolved fluorescence lifetime imaging microscopy (FLIM) was employed with FP tagged PDK1 to investigate dynamic interactions in intact cells in situ and in vivo. PDK1 was shown to dimerise in a manner dependent on PI 3-kinase activity and PDK1 PH domain lipid binding. To detail the structure of the observed intermolecular interaction, recombinant FP labelled PDK1 was produced with insect cells. Measurement of the rise in acceptor fluorescence during FRET in vitro indicated the PDK1 dimer pair exists in an antiparallel arrangement. These results provide the first insight on the structure of the dimer and demonstrate that the generation of 3-phosphorylated lipids is required for its formation.
18
Andreiuk, Bohdan. "Self-assembly of ionic fluorescent dyes inside polymer nanoparticles : engineering bright fluorescence and switching." Thesis, Strasbourg, 2017. http://www.theses.fr/2017STRAF027/document.
Full textAbstract:
L’encapsulation dans des nanomatériaux de polymères de colorants ioniques à l’aide de contre-ions hydrophobes volumineux apparaît être une méthode très efficace pour générer des nanoparticules (NPs) fluorescentes ultra-brillantes pour la bioimagerie. Nous avons d’abord étendu cette approche par contre-ions aux colorants cyanine opérant dans la gamme du bleu au proche infra-rouge. A partir de NPs chargés en cyanines, une methode de code-barre multicolore pour le traçage cellulaire à long terme a été développé. Ensuite, le rôle des contre-ions hydrophobes volumineux dans l’auto-assemblage des colorants cationiques à l’intérieur des NPs de polymères a été étudié en testant une large collection d’anions. Nous avons montré qu’une forte hydrophobicité du contre-ion augmente l’encapsulation du colorant, régule son clustering et empêche l’agrégation de nanoparticules, alors qu’une grande taille empêche l’auto-inhibition de fluorescence. Enfin, nous avons introduit les contre-ions à base d’aluminates et de barbiturates, qui sur-performent les tetraphénylborates fluorés. Ce travail procure une base solide au concept d’émission et d’encapsulation augmentées par contre-ions pour la préparation de NPs chargés en colorants fluorescentsEncapsulation of ionic dyes with help of bulky hydrophobic counterions into polymer nanomaterials emerged as powerful method for generating ultrabright fluorescent nanoparticles (NPs) for bioimaging. Here, this counterion-based approach is extended to cyanine dyes, operating from blue to near-infrared range. Based on cyanine-loaded NPs, a multicolour cell barcoding method for long-term cell tracking is developed. Second, the role of bulky hydrophobic counterion in self-assembly of cationic dyes inside polymeric NPs is studied by testing a large library of anions. We show that high hydrophobicity of a counterion enhances dye encapsulation, prevents particle aggregation and tunes dye clustering, while large size prevents dyes from self-quenching. Third, counterions based on aluminates and barbiturates are shown to outperform fluorinated tetraphenylborates. This work provides a solid basis for counterion-enhanced encapsulation and emission concept in preparation of dye-loaded fluorescent NPs
19
Regmi, Raju. "Nanophotonic antennas for enhanced single-molecule fluorescence detection and nanospectroscopy in living cells membranes." Doctoral thesis, Universitat Politècnica de Catalunya, 2017. http://hdl.handle.net/10803/461707.
Full textAbstract:
Single-molecule fluorescence spectroscopy has revolutionized the field of biophysical sciences by enabling visualization of dynamic molecular interactions and nanoscopic features with high spatiotemporal resolution. Monitoring enzymatic reactions and studying diffusion dynamics of individual molecules (such as lipids and proteins) help us understand how these nanoscopic entities influence and control various biochemical processes. Nanophotonic antennas can efficiently localize electromagnetic radiation into nanoscale spatial dimensions comparable to single bio-molecules (<10 nm). These ultra-confined illumination hotspots thereby offer opportunity to follow single-molecule events at physiological expression levels.
In this thesis, we explore various photonic nanoantenna platforms (double nanohole apertures, dimer nanogap antennas and planar "antenna-in-box'') and demonstrate their application in enhanced single-molecule fluorescence detection. Using fluorescence burst analysis, fluorescence correlation spectroscopy (FCS), time-correlated TCSPC measurements, and near field simulations, we quantify nanoantenna detection volumes, fluorescence enhancement factors and discuss the fluorescence photodynamic accelerations mediated by optical nanoantennas. An alternative to plasmonic structures, all-dielectric nanoantenna based on silicon nanogap is also demonstrated to enhance the fluorescence detection of single molecules diffusing in concentrated solutions.
Further, using resonant planar "antenna-in-box'' devices we investigate the diffusion dynamics of phosphoethanolamine and sphingomyelin on the plasma membrane of living cells and discuss the results in the context of lipid rafts. Together with cholesterol depletion experiments, we provide evidence of cholesterol-induced nanodomain partitioning within less than 10 nm diameters and characteristic times being ~100 microsecondsLa espectroscopia de fluorescencia de una sola molecula ha revolucionado el campo de las ciencias biofisicas, permitiendo la visualizacion de interacciones moleculares dinamicas y caracteristicas nanoscopicas con alta resolucion espaciotemporal. La monitorizacion de las reacciones enzimaticas y el analisis de la dinamica de difusion de moleculas individuales (como lipidos y proteinas) nos ayudan a comprender como estas entidades nanoscopicas influyen y controlan diversos procesos bioquimicos. Las antenas nanofotonicas pueden localizar eficientemente la radiacion electromagnetica en dimensiones espaciales en nanoescala, comparables a biomoleculas unicas (<10 nm). Estos hotspots de iluminacion ultra configurados ofrecen de este modo la oportunidad de monitorizar eventos de molecula unica a niveles de expresion fisiologica. En esta tesis, exploramos varias plataformas fotonicas de nanoantenas (double nanohole aperture, dimero nanogap antenas y "antenna-in-box" planares) y demostramos su aplicacion en la mejora de la deteccion una sola molecula de fluorescencia. Utilizando el analisis por explosion de fluorescencia, espectroscopia de correlacion de fluorescencia (FCS), medidas TCSPC correlacionadas en el tiempo y simulaciones de campo cercano, cuantificamos volumenes de deteccion de nanoantenas, factores de mejora de fluorescencia y discutimos las aceleraciones fotodinámicas de fluorescencia mediada por nanoantennas opticas. Las nanoantennas dielectricas basadas en nanogaps de silico se han propuesto como una alternativa en el realce de la deteccion de fluorescencia de difusion de moleculas unicas en soluciones concentradas. Ademas, utilizando dispositivos resonantes planares de "antenna-in-box", investigamos la dinamica de difusion de la fosfoetanolamina y la esfingomielina en la membrana plasmatica de las celulas vivas y discutimos los resultados en el contexto de las balsas lipidicas. Junto con experimentos de dismincion de colesterol, proporcionamos pruebas de division inducida por colesterol en el nanodominio dentro de diametros menors de 10 nm y con tiempos caracteristicos de ~100 microsegundos.
La spectroscopie de fluorescence d'une seule molécule a révolutionné le domaine des sciences biophysiques, permettant la visualisation d'interactions moléculaires dynamiques et de caractéristiques nanoscopiques à haute résolution spatio-temporelle. Le suivi des réactions enzymatiques et l'analyse de la dynamique de diffusion des molécules individuelles (telles que les lipides et les protéines) nous aident à comprendre comment ces entités nanoscopiques influencent et contrôlent divers processus biochimiques. Les antennes nanophotoniques peuvent localiser efficacement le rayonnement électromagnétique à des dimensions spatiales nanométriques, comparables à des biomolécules uniques (<10 nm). Ces hotspots d'éclairage ultra-configurés offrent la possibilité de surveiller les événements de molécules uniques à des niveaux d'expression physiologiques. Dans ce mémoire, nous examinons plusieurs plates-formes photoniques nanoantennas (nanotrou à double ouverture, I antennes Dimer nanoespace et plane « antenne-in-box ») et de démontrer son application dans l'amélioration de la détection d'une fluorescence seule molécule. Utilisation de l'analyse par spectroscopie de fluorescence d'explosion corrélation de fluorescence (FCS), les mesures TCSPC corrélées dans le temps et proches des simulations champ quantifier les volumes de détection de nanoantennas, les facteurs d'amélioration fluorescence et discuter des accélérations photodynamiques fluorescence médiée nanoantennas opticas. Des nanoantennas diélectriques à base de nanogap silico ont été proposées comme alternative dans l'amélioration de la détection par fluorescence de la diffusion de molécules uniques dans des solutions concentrées. En outre, l'utilisation de "plan d'antenne-in-box" dispositifs de résonance, nous étudions la dynamique de diffusion de phosphoéthanolamine et sphingomyéline dans la membrane plasmique des cellules vivantes et de discuter des résultats dans le contexte des radeaux lipidiques. Conjointement avec des expériences de réduction du cholestérol, nous fournissons des tests de division induits par le cholestérol dans le nanodomaine dans des diamètres plus petits de 10 nm et avec des temps caractéristiques de ~ 100 microsecondes.
20
Rasmussen, John C. "Development of a radiative transport based, fluorescence-enhanced, frequency-domain small animal imaging system." Thesis, [College Station, Tex. : Texas A&M University, 2006. http://hdl.handle.net/1969.1/ETD-TAMU-1067.
Full text
21
Moores, Amy N. "Developing a tip-enhanced fluorescence microscope for applications in super-resolution and correlative imaging." Thesis, University of Sheffield, 2017. http://etheses.whiterose.ac.uk/19614/.
Full textAbstract:
This thesis describes the development of a tip-enhanced fluorescence microscope, based upon combining confocal fluorescence methods with a commercially-available atomic force microscope (AFM). A microscope which is capable of simultaneous fluorescence and atomic force measurements has been realised. This has been achieved by mounting an AFM onto an inverted optical microscope, allowing the sample to be fluorescently excited from underneath. The incident position of the excitation spot at the sample can be controlled by a 2D galvanometer present in the excitation beam path. A program has been developed which aligns the laser spot with the AFM-tip by correlating sample features, and then applying a corresponding voltage to the galvanometer, in order to translate the beam towards the AFM-tip. A result of this process is that the fields-of-view of the fluorescence and atomic force images are also aligned, enabling simultaneous correlative microscopy. The benefits of performing these techniques simultaneously include eliminating the need to image over large areas with both techniques to ensure overlapping fields-of-view (as would be required if these measurements were being performed consecutively). It also unlocks the potential to track the mechanical changes of a known structure over time. Moreover, elements of the alignment program may be useful for general applications in correlative microscopy, providing an automated tool for overlaying images which have been obtained using different techniques. Alongside simultaneous imaging, this alignment method is also a potential technique for introducing a tip-enhancement effect into this particular instrument. A method has been developed which acquires data from a single photon counting module (SPCM) and the AFM using a LabVIEW field programmable gate array (FPGA), and subsequently correlates the number of detected photons from the sample with the position of the AFM-tip at that time. Although fluorescence enhancement was not detected using this instrument, the method was sufficient enough to detect scatter as the AFM-tip made contact with the sample; this is evidence that the method can successfully measure the number of photons detected with respect to tip-sample separation and should be able to also detect an increase in photons due to enhancement, if the effect can be optimised.
22
Regmi, Raju. "Nanophotonic antennas for enhanced single-molecule fluorescence detection and nanospectroscopy in living cell membranes." Thesis, Aix-Marseille, 2017. http://www.theses.fr/2017AIXM0523/document.
Full textAbstract:
La spectroscopie de fluorescence de molécule individuelle a révolutionné le domaine des sciences biophysiques, en permettant la visualisation des interactions moléculaires dynamiques et des caractéristiques nanoscopiques avec une haute résolution spatio-temporelle. Le contrôle des réactions enzymatiques et l'étude de la dynamique de diffusion de molécules individuelles permet de comprendre l'influence et le contrôle de ces entités nanoscopiques sur plusieurs processus biophysiques. La nanophotonique basée sur la plasmonique offre des nouvelles opportunités de suivi d'évènements à molécule unique, puisque il est possible de confiner des champs électromagnétiques dans les hotspots à nano-échelle, à dimensions spatiales comparables à une molécule unique. Dans ce projet de thèse, nous explorons plusieurs plateformes de nanoantennas photoniques avec des hotspots, et nous avons démontré les applications dans l'amélioration de la spectroscopie de fluorescence de molécule individuelle. En utilisant la fluorescence burst analysis, l'analyse de fluctuations temporelle de fluorescence,TCSPC, nous quantifions les facteurs d'amélioration de fluorescence, les volumes de détection de nanoantennas; ainsi, nous discutons l'accélération de fluorescence photo dynamique. En alternative aux structures plasmoniques, des antennes diélectriques basées sur les dimères en silicone ont aussi démontré d'améliorer la détection de fluorescence à molécule unique, pour des concentrations micro molaires physiologiquement pertinentes. En outre, nous explorons des systèmes planaires antennas in box pour l'investigation de la dynamique de diffusion de la PE et de la SM dans les membranes des cellules vivantesSingle-molecule fluorescence spectroscopy has revolutionized the field of biophysical sciences by enabling visualization of dynamic molecular interactions and nanoscopic features with high spatiotemporal resolution. Monitoring enzymatic reactions and studying diffusion dynamics of individual molecules help us understand how these nanoscopic entities influence and control various biochemical processes. Nanophotonic antennas can efficiently localize electromagnetic radiation into nanoscale spatial dimensions comparable to single bio-molecules. These confined illumination hotspots there by offer the opportunity to follow single-molecule events at physiological expression levels. In this thesis, we explore various photonic nanoantenna platforms and demonstrate their application in enhanced single-molecule fluorescence detection. Using fluorescence burst analysis, fluorescence correlation spectroscopy (FCS), time-correlated TCSPC measurements, and near field simulations, we quantify nanoantenna detection volumes, fluorescence enhancement factors and discuss the fluorescence photodynamic accelerations mediated by optical antennas. Further, using resonant planar antenna-in-box devices we investigate the diffusion dynamics of phosphoethanolamine and sphingomyelin on the plasma membrane of living cells and discuss the results in the context of lipid rafts. Together with cholesterol depletion experiments, we provide evidence of cholesterol-induced nanodomain partitioning within less than 10~nm diameters and characteristic times being ~100 microseconds
23
Rane, Lukas. "Improving the temporal resolution of a microspectrometer for the study of the photophysics of enhanced green fluorescent protein." Thesis, KTH, Tillämpad fysik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-300136.
Full textAbstract:
The use of fluorescent proteins as fluorescent markers has exploded over the last decades. In particular due to the development of advanced microscopy for live cell measurements, dynamic molecular studies down to single molecule levels and for superresolution microscopy. Many variants of fluorescent proteins exist with varying properties, such as emission color, photostability and brightness. These properties enable advanced applications, like timeresolved imaging or imaging below the diffraction limit. However, the photophysics of fluorescent proteins are complex and in many aspects quite unexplored. The triplet state in particular, is a central photophysical state because it is an entrance gate to an ensamble of deleterious photochemical processes that compromise the photostability of fluorescent proteins.The Pixel team at Institute de Biologie Structurale in France, is mainly focused on developing fluorescent proteins for advanced fluorescence imaging. One of the goals is to understand the influence of photochemistry on the properties of fluorescent proteins.In this project, a method to indirectly observe the triplet state in the prototypical EGFP fluorescent protein was developed. The introduction of new hardware and software, coupled to biophysical experiments, required an interdisciplinary strategy to tackle the obstacles during the route. Experiments under different environmental conditions to test the influence on the population of the triplet state of viscosity, pH, UV and infrared light, triplet state quenchers and temperature were performed.The results show that temperature and laser power greatly influence the triplet state kinetics in EGFP. Notably, it was found that the triplet state lifetime strongly increases at cryotemperature in comparison to roomtemperature. Overall, the newly developed setup and our preliminary results on EGFP open the door to novel studies on the photophysical properties of fluorescent proteins.Nyttjandet av fluorescerande proteiner som markörer har exploderat de senaste årtionden. Speciellt till följd av utvecklingen av avancerad mikroskopi för levande cellmätningar, dynamiska molekylära studier ned till enstaka molekylnivåer och för superupplösnings mikroskopi. Många varianter av fluorescerande proteiner förekommer med varierande egenskaper så som färg, fotostabilitet och ljusstyrka. Dessa proteiner möjliggör avancerade applikationer, som tidsupplöst bildgivning eller bildgivning med upplösning under diffraktionsgränsen. Fotofysiken bakom fluorescerande proteiner är komplex och i många aspekter ganska outforskad. Triplettillståndet är ett centralt fotofysiskt tillstånd eftersom det är en ingångsport till en rad skadliga fotokemiska processer som äventyrar fotostabiliteten hos fluorescerance proteiner.Pixelteamet på Institute de Biologie Structurale i Frankrike, fokuserar huvudsakligen på utveckling av fluorescerande proteiner för avancerad fluorescerande bildgivning. Ett av målen är att förstå hur fotokemi påverkar egenskaperna hos fluorescerande proteiner.I det här projektet har en metod för att indirekt observera triplettillståndet i det prototypiska fluorescerande proteinet EGFP utvecklats. Introduktionen av ny hårdvara och mjukvara, i kombination med biofysikaliska experiment, krävde en interdisiplinär strategi för att tackla utmaningarna under vägens gång. Experiment under olika miljömässiga förhållanden gjordes för att testa hur populationen av triplettillståndet påverkas till följd av viskositet, pH, UV och infrarött ljus, triplettillståndshämmare och temperatur.Resultaten visar att temperatur och lasereffekt har en stor påverkan på triplettillståndet och dess kinetik hos EGFP. Noterbart är att triplettillståndets livstid ökar kraftigt i kryotemperatur i jämförelse med rumstemperatur. Sammanfattningsvis så utvecklades en ny experimentel uppställning och de tidiga resultaten från EGFP har öppnat dörren för nya studier rörande de fotofysiska egenskaperna hos fluorescerande proteiner.
24
Spaeth, Hans D. "DNA-Enhanced Efficiency and Luminance of Organic Light Emitting Diodes." University of Cincinnati / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1342729062.
Full text
25
Luković, Elvedin. "Development of selective peptide- and protein-based reporters of kinase activity utilizing chelation-enhanced fluorescence." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/55098.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2009.Vita. Cataloged from PDF version of thesis.
Includes bibliographical references.
Catalyzed by kinases, serine/threonine and tyrosine phosphorylation is a vital mechanism of intracellular regulation and is involved in nearly every aspect of normal, as well as aberrant, cell function. With more than 500 protein kinases present in the human genome, the need for probes that can rapidly and selectively report the activity of a single kinase or a discreet subset of related kinases is crucial, particularly as researchers move to increasingly complex, and more relevant, systems to study the effects of dysregulated kinase behavior. We previously developed sulfonamido-oxine (Sox)-based fluorescent peptides following a P-turn focused (BTF) design. Upon phosphorylation of the Sox-containing peptide, the chromophore binds Mg + and undergoes chelation-enhanced fluorescence (CHEF). However, due to the BTF design limitation, only residues C- or N-terminal to the phosphorylated residue were used to specify the target kinase. To address this drawback, the recognition-domain focused (RDF) strategy, which also relies on CHEF, has been developed. In this approach, the Sox sensing moiety is introduced on the cysteine side chain (C-Sox), thereby allowing inclusion of extended kinase binding determinants, which are used to construct chemosensors for multiple Ser/Thr and Tyr kinases with greatly enhanced selectivity. Moreover, a high throughput mass spectrometry-based screening method that builds additional selectivity into RDF Sox-based probes for Ser/Thr kinases was also developed. Using this approach, it should be possible to construct short peptide probes with enhanced catalytic efficiency for virtually any kinase.
(cont.) To expand the scope of CHEF-based sensors, beyond kinases that derive specificity from the short consensus sequence, a highly selective ERK sensor was prepared via semisynthesis by combining a recombinant kinase docking domain, PNT, with a synthetic sensing module that included the Sox chromophore. This probe was used to exclusively monitor ERK1/2 activity in unfractionated cell lysates in the absence of off-target kinase inhibitors. Furthermore, to improve the photophysical properties of the probes for cellular studies, we developed several oxine-based CHEF chromophores utilizing numerous approaches including the versatile click chemistry. The most promising derivative, p-bromophenyltriazoyl-oxine (Clk), displays a significant bathochromic shift in the excitation (15 nm) and emission (40 nm) maxima compared to Sox, and efficiently reports kinase activity when incorporated into peptides as a C-Clk residue. Together, the results presented in this thesis indicate the power that the CHEF-based sensors have to selectively, rapidly and with great sensitivity deliver new insight into the role of in vitro and endogenous kinases in various processes and under a variety of circumstances.
by Elvedin Luković.
Ph.D.
26
Stein-Merlob, Ashley F. "Nanoparticle-Enhanced Near Infrared Fluorescence Imaging of Atheroma Detects Thrombosis-Prone Plaques Prior to Rupture." Thesis, Harvard University, 2015. http://nrs.harvard.edu/urn-3:HUL.InstRepos:15821600.
Full textAbstract:
Introduction: Acute coronary syndromes - including unstable angina, acute myocardial infarction and sudden death - are primarily due to sudden luminal thrombosis from disruption of an atherosclerotic plaque. It has been established that inflammation plays an important role in atherogenesis and the destabilization of plaques. However, the role of inflammation in catalyzing plaque rupture is incompletely understood. Here, we experimentally investigated the in vivo spatial distribution of a novel atheroma cell targeted near-infrared fluorescence (NIRF) imaging agent, CLIO-CyAm7, prior to triggered plaque rupture, using intravascular molecular imaging. We hypothesized that CLIO-CyAm7 would illuminate macrophages on in vivo intravascular NIRF imaging and preferentially localize to atheroma that develop plaque thrombosis under triggering conditions.
Methods: Atherosclerosis was induced in rabbits (n=28) using a 12-week hyperlipidemic diet with alternating 1% high cholesterol and normal chow with concomitant aortic balloon injury at 2 weeks. Rabbits were injected with 2.5mg/kg of CLIO-CyAm7 24 hours prior to in vivo imaging. In vivo NIRF and intravascular ultrasound (IVUS) imaging were used to assess baseline structural and inflammation characteristics of atheroma. Control rabbits (n=6) were sacrificed prior to triggering. Pharmacological triggering was performed using Russell’s Viper Venom (0.15mg/kg IP) and histamine (0.02mg/kg IV) injections twice over 48-hours. IVUS imaging was repeated prior to sacrifice to identify luminal thrombi in vivo. NIRF imaging was quantified using target-to-background ratio (TBR), the ratio between an area of atheroma compared to normal, uninjured aorta. A subset of rabbits (n=7) was injected with Evans Blue (6mL 0.5% IV) 30 minutes prior to sacrifice to identify permeability of the endothelium. After sacrifice, ex vivo imaging, fluorescence microscopy (FM), RAM-11 immunofluorescence (IF) of macrophages, alpha-smooth muscle actin IF for smooth muscle cells, CD31 IF for endothelial cells, and Carstairs’ staining for fibrin and collagen, were performed systematically along the length of the aorta at 1.5cm increments. Data is presented as mean±SD.
Results: On microscopy, CLIO-CyAm7 localized primarily at the intimal-luminal border of atheroma, with some penetration into the media and adventitia. There was significantly higher CLIO-CyAm7 accumulation in areas of atheroma compared to control segments of the aorta (1.73±1.9% vs. 0.13±0.28%, p<0.0001). On IF, CLIO-CyAm7 signal correlated with subsets of macrophages, endothelial cells and smooth muscle cells in atheroma with minimal CLIO-CyAm7 evident in normal arteries. Evans blue showed increased endothelial permeability in regions of increased subendothelial CLIO-CyAm7 accumulation. CD31+ endothelial cells in the neovessels at the intima-media border indicated delivery of CLIO-CyAm7 via vaso vasorum. In vivo, CLIO-CyAm7+ plaques were detectable via intravascular NIRF imaging. Areas of atherosclerosis, determined by IVUS, showed significantly higher NIRF peak TBR than normal segments of the aorta (2.86±1.82 vs. 1.55±0.65, p=0.001). In vivo IVUS imaging and Carstairs’ staining for fibrin identified plaque thrombosis in 10 of 15 rabbits undergoing the triggered protocol (67%). Notably, plaques with luminal thrombosis showed significantly higher CLIO- CyAm7 accumulation compared to undisrupted atheroma (2.1±1.7% vs. 1.5±1.9%, p=0.0446), indicating that atheroma cell phagocytic capacity may underlie plaque rupture.
Conclusion: CLIO-CyAm7 is a novel NIRF molecular imaging agent that identifies a subset of phagocytically active cells that are increased in atheroma prone to plaque thrombosis. Intravascular 2D NIRF imaging provides a promising future translational tool for high-resolution imaging of biologically high-risk plaques.
27
Liu, Jun. "Biomarker Detection at Risk Forecasting Level Using Metal-Enhanced Fluorescence Combined with Surface Acoustic Wave." Scholar Commons, 2016. http://scholarcommons.usf.edu/etd/6534.
Full textAbstract:
In this paper, metal-enhanced fluorescence (MEF) technique is used to lower the detection limit of carcinoembryonic antigen (CEA) which is able to be utilized in forecasting the risk of having certain kinds of cancers, especially colon and rectal cancer. By incubating silver nanocubes (Ag NCs) on the surface of the chips, the detection limit goes down to below 1ng/mL of CEA. Also, when combining MEF with surface acoustic wave (SAW) devices, the incubation time between antigen and antibody will decrease significantly with the fluorescence signal keeping similar or higher level.
28
Wada, Toshiaki. "Enhanced anastomotic healing by Daikenchuto(TJ-100) in rats." Kyoto University, 2019. http://hdl.handle.net/2433/236610.
Full text
29
García, Guzmán Claudia María. "Optical probes for enhanced targeting of cancer." Thesis, University of Edinburgh, 2017. http://hdl.handle.net/1842/28902.
Full textAbstract:
The diagnosis of cancer in early stages is an unmet clinical need, especially in view that current treatments for cancer cannot address metastatic disease. Cancer aberration processes are associated to an increase in the production of reactive oxygen species (ROS). Chemical probes that can specifically detect these species are potentially useful as medical diagnostics and research tools for cancer imaging. One of the aims of my thesis was the design and synthesis of the activatable fluorescent probes based on small molecule fluorophores modified with chemically reactive moieties. The activation of these moieties by defined targets (e.g. ROS) results in the activation of the fluorophore and subsequent emission of a fluorescent signal. Two libraries of fluorescence probes for the detection of ROS have been designed and synthesised: 1) hydrocyanine-based probes as silent fluorophores that can be activated with superoxide ions, 2) coumarin-based hydrogen peroxide probes with red-shifted fluorescent properties and different boronate activatable groups for hydrogen peroxide sensing. We have performed in vitro assays to evaluate the fluorescence response of our probes as well as experiments in relevant live cells to assess their application for detection of ROS in live cells with molecular resolution. Moreover, cancer cells also overexpress Epidermal Growth Factor Receptors (EGFR). Surface-enhanced Raman scattering (SERS) nanotags that can recognize specifically EGFR receptors in cells are promising tools for the enhanced diagnosis of cancer. Two near-infrared cyanine Raman reporters were synthesized with a carboxylic group that was conjugated to cysteamine for derivatization of gold nanoparticles (AuNPs). This work was performed in the CSIR-NIIST (Kerala, India), where I did a 3-month PhD placement. I conjugated the cyanine reporters to spherical AuNPs of 40 nm diameter, and measured their Raman intensity and stability. The best SERS nanotags were selected for encapsulation with PEG and subsequently derivatization with anti-EGFR-EP22 antibodies. In vitro characterization of the SERS nanotags was performed: SERS and absorbance spectra, electron microscopy images as well as SERS imaging experiments in A549 lung cancer cells.
30
Cohanoschi, Ion. "THREE-PHOTON ABSORPTION PROCESS IN ORGANIC DYES ENHANCED BY SURFACE PLASMON RESONANCE." Doctoral diss., University of Central Florida, 2006. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3891.
Full textAbstract:
Multi-photon absorption processes have received significant attention from the scientific community during the last decade, mainly because of their potential applications in optical limiting, data storage and biomedical fields. Perhaps, one of the most investigated processes studied so far has been two-photon absorption (2PA). These investigations have resulted in successful applications in all the fields mentioned above. However, 2PA present some limitations in the biomedical field when pumping at typical 2PA wavelengths. In order to overcome these limitations, three-photon absorption (3PA) process has been proposed. However, 3PA in organic molecules has a disadvantage, typical values of σ3' are small (10-81 cm6s2/photon2), therefore, 3PA excitation requires high irradiances to induce the promotion of electrons from the ground state to the final excited state. To overcome this obstacle, specific molecules that exhibit large 3PA cross-section must be designed. Thus far, there is a lack of systematic studies that correlate 3PA processes with the molecular structure of organic compounds. In order to fill the existent gap in 3PA molecular engineering, in this dissertation we have investigated the structure/property relationship for a new family of fluorene derivatives with very high three-photon absorption cross-sections. We demonstrated that the symmetric intramolecular charge transfer as well as the -electron conjugation length enhances the 3PA cross-section of fluorene derivatives. In addition, we showed that the withdrawing electron character of the attractor groups in a pull-pull geometry proved greater 3PA cross-section. After looking for alternative ways to enhance the effective σ3' of organic molecules, we investigated the enhancement of two- and three-photon absorption processes by means of Surface Plasmon. We demonstrated an enhancement of the effective two- and three-photon absorption cross-section of an organic compound of 480 and 30 folds, respectively. We proved that the enhancement is a direct consequence of the electric field enhancement at a metal/buffer interface. Next, motivated by the demands for new materials with enhanced nonlinear optical properties, we studied the 3PA of Hematoporphyrin IX and J-aggregate supramolecular systems. As a result, we were able to propose the use of 3PA in photodynamic therapy using Photofrin, the only drug approved by the FDA for PDT.Ph.D.
Other
Optics and Photonics
Optics
31
Kumas, Gozde. "Detecting G-protein Coupled Receptor Interactions Using Enhanced Green Fluorescent Protein Reassembly." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614136/index.pdf.
Full textAbstract:
The largest class of cell surface receptors in mammalian genomes is the superfamily of G protein-coupled receptors (GPCRs) which are activated by a wide range of extracellular responses such as hormones, pheromones, odorants, and neurotransmitters. Drugs which have therapeutic effects on a wide range of diseases are act on GPCRs. In contrast to traditional idea, it is recently getting accepted that G-protein coupled receptors can form homo- and hetero-dimers and this interaction could have important role on maturation, internalization, function or/and pharmacology.
Bimolecular fluorescence complementation technique (BiFC)is an innovative approach based on the reassembly of protein fragments which directly report interactions. In our study we implemented this technique for detecting and visualizing the GPCR interactions in yeast cells. The enhanced green fluorescent protein (EGFP) fractionated into two fragments at genetic level which does not possess fluorescent function. The target proteins which are going to be tested in terms of interaction are modified with the non-functional fragments, to produce the fusion proteins. The interaction between two target proteins, in this study Ste2p receptors which are alpha pheromone receptors from Saccharomyces cerevisiae, enable the fragments to come in a close proximity and reassemble. After reassembly, EGFP regains its fluorescent function which provides a direct read-out for the detection of interaction. Further studies are required to determine subcellular localization of the interaction. Moreover, by using the fusion protein partners constructed in this study, effects of agonist/antagonist binding and post-translational modifications such as glycosylation and phosphorylation can be examined. Apart from all, optimized conditions for BiFC technique will guide for revealing new protein-protein interactions.
32
Godavarty, Anuradha. "Fluorescence enhanced optical tomography on breast phantoms with measurements using a gain modulated intensified CCD imaging system." Texas A&M University, 2003. http://hdl.handle.net/1969.1/2184.
Full textAbstract:
Fluorescence-enhanced optical imaging using near-infrared (NIR) light developed for in-vivo molecular targeting and reporting of cancer provides promising opportunities for diagnostic imaging. However, prior to the administration of unproven contrast agents, the benefits of fluorescence-enhanced optical imaging must be assessed in feasibility phantom studies.
A novel intensified charge-coupled device (ICCD) imaging system has been developed to perform 3-D fluorescence tomographic imaging in the frequency-domain using near-infrared contrast agents. This study is unique since it (i) employs a large tissue-mimicking phantom (~1087 cc), which is shaped and sized to resemble a female breast and part of the extended chest wall region, and (ii) enables rapid data acquisition in the frequency-domain by using a gain-modulated ICCD camera. Diagnostic 3-D fluorescence-enhanced optical tomography is demonstrated using 0.5-1 cc single and multiple targets contrasted from their surrounding by ??M concentrations of Indocyanine green (ICG) in the breast-shaped phantom (10 cm diameter), under varying conditions of target-to-background absorption contrast ratios (1:0 and 100:1) and target depths (up to 3 cm deep). Boundary surface fluorescence measurements of referenced amplitude and phase shift were used along with the coupled diffusion equation of light propagation in order to perform 3-D image reconstructions using the approximate extended Kalman filter (AEKF) algorithm, and hence differentiate the target from the background based on fluorescent optical contrast.
Detection of single and multiple targets is demonstrated under various conditions of target depths (up to 2 cm deep), absorption optical contrast ratio (1:0 and 100:1), target volumes (0.5-1 cc), and multiple targets (up to three 0.5 cc targets). The feasibility of 3-D image reconstructions from simultaneous multiple point excitation sources are presented. Preliminary lifetime imaging studies with 1:2 and 2:1 optical contrast in fluorescence lifetime of the contrast agents is also demonstrated. The specificity of the optical imager is further assessed from homogeneous phantom studies containing no fluorescently contrasted targets.
While nuclear imaging currently provides clinical diagnostic opportunities using radioactive tracers, molecular targeting of tumors using non-ionizing NIR contrast agents tomographically imaged using the frequency-domain ICCD imaging system could possibly become a new method of diagnostic imaging.
33
Rollakanti, Kishore Reddy. "Protoporphyrin IX Fluorescence for Enhanced Photodynamic Diagnosis and Photodynamic Therapy in Murine Models of Skin and Breast Cancer." Cleveland State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=csu1431466604.
Full text
34
Ljungblad, Jonas. "Antibody-conjugated Gold Nanoparticles integrated in a fluorescence based Biochip." Thesis, Linköping University, Department of Physics, Chemistry and Biology, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-50619.
Full textAbstract:
Gold nanoparticles exhibit remarkable optical properties and could prove useful in sensitive biosensing applications. Upon illumination gold nanoparticles produce localized surface plasmons, which influence nearby fluorophores and an enhancement in their fluorescence intensity can be observed. This property makes gold nanoparticles attractive for enhancing optical signals.
In this project gold nanoparticles were functionalized with an antibody and immobilized to the surface of an existing biochip platform based on fluorescence. The aim was to investigate the possibility of obtaining an increased fluorescence signal from the gold nanoparticles. Two different conjugation procedures were investigated, direct physisorption and covalent attachment of the antibodies to the particles. Activity of bound antibodies was confirmed in both cases.
The on-chip fluorescence intensity produced by the different conjugates was monitored by use a specialized fluorescence reader designed for point-of-care use. AFM and SEM were used to determine the surface concentration of particles. A correlation between the produced fluorescence intensity and the surface concentration could be seen.
35
Strong, Robert James. "Enhanced Static Mixer Design Analysis in Lattice Boltzmann Solver." University of Dayton / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1599754613521417.
Full text
36
Larsson, Mina. "Application of Raman and Fluorescence Spectroscopy to Single Chromatographic Beads." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-5741.
Full text
37
Ebai, Tonge. "Development of Enhanced Molecular Diagnostic Tools for Protein Detection and Analysis." Doctoral thesis, Uppsala universitet, Molekylära verktyg, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-320380.
Full textAbstract:
Improved diagnosis, prognosis and disease follow-up is a fundamental procedure and a constant challenge in medicine. Among the different molecular biomarkers, proteins are the essential regulatory component in blood; hence, by developing enhanced specific and sensitive molecular tools will gives great insight into the different processes in disease treatment. In this thesis, we build on the proximity ligation assay to develop and apply new adaptable methods to facilitate protein detection. In paper I, I present a variant of the proximity ligation assay (we call PLARCA) using micro titer plate for detection and quantification of protein using optical density as readout in the fluorometer. PLARCA detected femtomolar levels of these proteins in patient samples, which was considerably below the detection threshold for ELISA. In paper II, we developed and adapted a new method into the in situ PLA methods for detection and identification of extracellular vesicles (EVs) using flow cytometry as readout (a method we call ExoPLA). We identified five target proteins on the surface of the Evs and using three colors, we identified the EV using flow cytometer. In paper III, we aim to improve the efficiency of in situ PLA by creating and developing new designs and versions of the assay we called Unfold probes Through comparison of detection of protein using in situ PLA versus Unfold probes, we observed considerable decrease in non-specific signals, and also a lower detection threshold. In paper IV, we describe the development of a solid phase proximity extension (sp-PEA) assay for protein detection and quantification. We compared detection of IL-8, TNF-alpha, IL-10 and IL-6 using spPEA and PEA; spPEA demonstrations over 2 orders of magnitudes in the lower detection concentrations by decreased in background noise.
38
Willis, Oliver Richard. "Peltier controlled growth of thin ice films in the laboratory and advancing the methodology of cavity enhanced laser induced fluorescence." Thesis, Durham University, 2014. http://etheses.dur.ac.uk/10858/.
Full textAbstract:
Cavity enhanced laser induced fluorescence (CELIF) is the first technique to combine cavity ring-down (CRDS) and laser induced fluorescence (LIF) spectroscopies in a single beam experiment. It has been shown previously to extend the dynamic range of CRDS to cover six orders of magnitude in total when observing BPEB concentrations seeded in a pulsed molecular beam. This study has extended CELIF to the most general application where a fluorescer or scatterer fills the length of a pulsed CRD experiment. Under these conditions CELIF is found to produce consistently smaller errors than CRD and is competitive with it but does not extend the dynamic range. Observing acetone fluorescence and nitrogen Rayleigh scattering it has been shown how the CRD signal normalises the LIF signal generated and that the normalisation remains linear during changes to the input powers, pressures and detector gains. Furthermore it has been shown it can be used to measure absolute quantum yields of fluorescence using acetone as an example. A peltier based set-up for cooling the upper surface of a prism for the growth of thin ice films at temperatures of the troposphere and stratosphere has been constructed. A full temperature range of 225-303K was displayed. Testing showed the optimal conditions of ice growth to be a rapid expansion directed at the surface. Ice films 2.5-11.8um thick have been successfully grown at 225.2+-0.2K covering, at maximum, 96% of a 1cm by 3cm stainless steel prism surface. During growth a strong migration over time to an area 0.028+-0.002cm^2 was seen caused by a temperature gradient on the surface, dT~5K from the centre to the outside of the surface along its short side. To monitor this and ice growth, two methods have been successfully installed and tested. A morphological analysis combined with video monitoring can accurately determine areas within 5% and a HeNe laser reflected from the ice is able to monitor surface thicknesses from interference patterns. Together these offer a complete method to characterise an ice film over the duration of an experiment.
39
Merritt, Travis Robert. "Optoperforation of Intact Plant Cells, Spectral Characterization of Alloy Disorder in InAsP Alloy Disorder in InAsP Alloys, and Bimetallic Concentric Surfaces for Metal-Enhanced Fluorescence in Upconverting Nanocrystals." Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/25148.
Full textAbstract:
The techniques of optoperforation, spectral characterization of alloy disorder, and metal-enhanced fluorescence were applied to previously unconsidered or disregarded systems in order to demonstrate that such applications are both feasible and consequential. These applications were the subject of three disparate works and, as such, are independently discussed.
Despite being ostensibly restricted to mammalian cells, optoperforation was demonstrated in intact plant cells by means of successful femtosecond-laser-mediated infiltration of a membrane impermeable dextran-conjugated dye into cells of vital Arabidopsis seedling stems. By monitoring the rate of dye uptake, and the reaction of both CFP-expressing vacuoles and nanocellulose substrates, the intensity and exposure time of the perforating laser were adjusted to values that both preserved cell vitality and permitted the laser-assisted uptake of the fluorophore. By using these calibrated laser parameters, dye was injected and later observed in targeted cells after 72 hours, all without deleteriously affecting the vital functions of those cells.
In the context of alloy disorder, photoluminescence of excitonic transitions in two InAsxP1-x alloys were studied through temperature and magnetic field strength dependencies, as well as compositionally-dependent time-resolved behavior. The spectral shape, behavior of the linewidths at high magnetic fields, and the divergence of the peak positions from band gap behavior at low temperatures indicated that alloy disorder exists in the x=0.40 composition while showing no considerable presence in the x=0.13 composition. The time-resolved photoluminescence spectrum for both compositions feature a fast and slow decay, with the slow decay lifetime in x=0.40 being longer than that of x=0.13, which may be due to carrier migration between localized exciton states in x=0.40.
In order to achieve broadband metal-enhanced fluorescence in upconverting NaYF4:Yb,Er nanocrystals, two nanocomposite architectures were proposed that retrofit metallic nanoshells to these lanthanide-doped nanocrystals. The typical monometallic construction was rejected in favor of architectures featuring Au-Ag bimetallic concentric surfaces, a decision supported by the considerable overlap of the calculated plasmon modes of the metallic structures with the emission and absorption spectrum of the nanocrystals. Furthermore, precursors of these nanocomposites were synthesized and photoluminescence measurements were carried out, ultimately verifying that these precursors produce the requisite upconversion emissions.Ph. D.
40
Park, Hyeyoung. "Kinetic and affinity analysis of hybridization reactions between PNA probes and DNA targets using surface plasmon field-enhanced fluorescence spectroscopy (SPFS)." [S.l.] : [s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=976835673.
Full text
41
Park, Hyeyoung. "Kinetic and affinity analysis of hybridization reactions between PNA probes and DNA targets using surface plasmon fiel enhanced fluorescence spectroscopy (SPFS)." Waabs GCA-Verl, 2005. http://deposit.ddb.de/cgi-bin/dokserv?id=2760979&prov=M&dok_var=1&dok_ext=htm.
Full text
42
Evers, Michael [Verfasser], Reginald [Gutachter] Birngruber, and Christian [Gutachter] Hübner. "Enhanced metabolic quantification of cells and tissue by label-free fluorescence lifetime imaging microscopy / Michael Evers ; Gutachter: Reginald Birngruber, Christian Hübner." Lübeck : Zentrale Hochschulbibliothek Lübeck, 2020. http://d-nb.info/1207503797/34.
Full text
43
Shiflett, Sheri. "PHYSIOLOGICAL MECHANISMS OF SHRUB ENCROACHMENT: LINKING ENHANCED HYDRAULIC CAPACITY TO EFFICIENT LIGHT CAPTURE AND PROCESSING." VCU Scholars Compass, 2013. http://scholarscompass.vcu.edu/etd/3208.
Full textAbstract:
Woody plant expansion has been documented for decades in many different ecosystems, often due to anthropogenic disturbances to the environment and yielding vast changes in ecosystem functioning. While causes and consequences of woody expansion have been well documented, few studies have investigated functional traits of woody species that promote rapid expansion in range. My objective was to determine if hydraulic efficiency confers enhanced photosynthetic efficiency so that functional traits representing light and water use may be possible mechanisms facilitating woody encroachment into grasslands and forest understories. I quantified leaf-level light environment, photosynthetic activity, and hydraulic characteristics of three sympatric broadleaf evergreens of varying leaf life span (Ilex opaca, Kalmia latifolia, and Myrica cerifera) in a deciduous forest understory to understand seasonal intra- and interspecific ranges of broadleaf evergreen physiology. Additionally, I investigated the effects of age on physiological efficiency of M. cerifera across a chronosequence (i.e., space for time substitution) of shrub thicket development in order to understand possible age-related physiological mechanisms facilitating shrub expansion. Lastly, I determined functional traits and resulting physiology that contribute to rapid expansion and thicket formation of an invasive, deciduous, N-fixing shrub, Elaeagnus umbellata, and a native, evergreen, N-fixing shrub M. cerifera. When compared to co-occurring evergreen species, electron transport rate (ETR) of M. cerifera was nearly double that of I. opaca or K. latifolia in summer. Photosynthetic capacity was positively related to hydraulic capacity among understory evergreens. Furthermore, photosynthetic and hydraulic efficiency of M. cerifera remained consistent despite considerable differences in thicket age and development. Both similar and contrasting functional traits of E. umbellata and M. cerifera allowed for enhanced light capture and water movement, and reductions in subcanopy light penetration. Enhanced hydraulic and photosynthetic efficiency relative to co-occurring species contributes to rapid range expansion and thicket formation by promoting enhanced productivity and limiting successful colonization of other species. My results indicate that there may be suites of functional traits linked to expansive success and thicket-formation, yet differences in functional traits between native and invasive species represent alternative strategies leading to rapid growth and thicketization.
44
Alvarez, Christine. "Diatoms in Photonics and Plasmonics: Characteristics and Applications." Thesis, The University of Arizona, 2016. http://hdl.handle.net/10150/612401.
Full textAbstract:
We have investigated some of the many photonic and plasmonic properties of the diatom Coscinodiscus wailesii. We start by showing that when diatom frustules are converted to high-index magnesium silicide while maintaining their structure, they exhibit a broad (1μm - 2μm) photonic bandgap that varies in wavelength according to the position and angle of the incident light on the frustule. We then demonstrate the use of the micro and nanostructured silica diatom frustule as a low-cost, easily prepared substrate for surface-enhanced Raman spectroscopy by coating the frustule in 25 nm of silver and a monolayer of thiophenol. Some potential applications of diatoms to water quality measurements are suggested, and steps are taken to image a diatom frustule and chloroplasts simultaneously in vivo using rhodamine 19 dye and fluorescence microscopy. We propose future experiments that could ascertain whether there is any biological effect of the light filtering properties of the diatom frustule, and put forth some suggestions as to how to influence the morphology and photonic properties of the frustule via chemical contaminants in the diatom seawater growth medium.
45
Samaimongkol, Panupon. "Surface plasmon resonance study of the purple gold (AuAl2) intermetallic, pH-responsive fluorescence gold nanoparticles, and gold nanosphere assembly." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/96549.
Full textAbstract:
In this dissertation, I have verified that the striking purple color of the intermetallic compound
AuAl2, also known as purple gold, originates from surface plasmons (SPs). This contrasts to a
previous assumption that this color is due to an interband absorption transition. The existence of
SPs was demonstrated by launching them in thin AuAl2 films in the Kretschmann configuration,
which enables us to measure the SP dispersion relation. I observed that the SP energy in thin films of purple gold is around 2.1 eV, comparable to previous work on the dielectric function of this
material. Furthermore, SP sensing using AuAl2 also shows the ability to measure the change in the refractive index of standard sucrose solution. AuAl2 in nanoparticle form is also discussed in terms of plasmonic applications, where Mie scattering theory predicts that the particle bears nearly
uniform absorption over the entire visible spectrum with an order magnitude higher than a lightabsorbing carbonaceous particle. The second topic of this dissertation focuses on plasmon enhanced fluorescence in gold nanoparticles (Au NPs). Here, I investigated the distance-dependent fluorescence emission of rhodamine green 110 fluorophores from Au NPs with tunable spacers. These spacers consist of polyelectrolyte multilayers (PEMs) consisting of poly(allylamine
hydrochloride) and poly(styrene sulfonate) assembled at pH 8.4. The distance between Au NPs and fluorophores was varied by changing the ambient pH from 3 to 10 and back, which causes the
swelling and deswelling of PEM spacer. Maximum fluorescence intensity with 4.0-fold enhancement was observed with 7-layer coated Au NPs at ambient pH 10 referenced to pH 3. The last topic of this dissertation examines a novel approach to assemble nanoparticles, in particular, dimers of gold nanospheres (NSs). 16 nm and 60 nm diameter NSs were connected using
photocleavable molecules as linkers. I showed that the orientation of the dimers can be controlled
with the polarization of UV illumination that cleaves the linkers, making dipolar patches. This type
of assembly provides a simple method with potential applications in multiple contexts, such as
biomedicine and nanorobotics.PHD
46
Luo, Sheng-Jhao, and 羅生兆. "Metal-enhanced fluorescence evaluation between fluorescent organic nanoparticle and silver nanorod." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/77uqw3.
Full textAbstract:
碩士國立中興大學
生醫工程研究所
106
Metal-enhanced fluorescence (MEF, metal-enhanced fluorescence) is a phenomenon of enhanced molecular fluorescence caused by plasma resonance (Surface plasmon resonance, SPR) on metal surfaces. In this paper, the effects of the fluorescence (fluorophore) and the metal-enhanced fluorescence (MEF, metal-enhanced fluorescence) on the surface of nano-silver are investigated by using the silver-nano rice noodle as the matrix. In the research process, the silver nanowires and Bannami particles were synthesized by chemical reduction method. The surface of the Bannami machine was modified and modified with three different organic sulfur compounds, and the fluorescent molecule was grafted on the surface of the silver-nano rice noodle or the silver-nano grains according to the effect of different organic sulfide and fluorescent molecule. The combination of the MEF effect after the formation of the mismatch between the fluorescence quality and the nanowires was screened by the spectral change, then the optimal ratio and coordination mechanism of the mismatch were discussed, and the established MEF platform and fluorescent organic nano-rice noodle (fluorescent organic nanowires) for comparison.
47
"Surface Enhanced Fluorescence: A Classic Electromagnetic Approach." Doctoral diss., 2013. http://hdl.handle.net/2286/R.I.18664.
Full textAbstract:
abstract: The fluorescence enhancement by a single Noble metal sphere is separated into excitation/absorption enhancement and the emission quantum yield enhancement. Incorporating the classical model of molecular spontaneous emission into the excitation/absorption transition, the excitation enhancement is calculated rigorously by electrodynamics in the frequency domain. The final formula for the excitation enhancement contains two parts: the primary field enhancement calculated from the Mie theory, and a derating factor due to the backscattering field from the molecule. When compared against a simplified model that only involves the primary Mie theory field calculation, this more rigorous model indicates that the excitation enhancement near the surface of the sphere is quenched severely due to the back-scattering field from the molecule. The degree of quenching depends in part on the bandwidth of the illumination because the presence of the sphere induces a red-shift in the absorption frequency of the molecule and at the same time broadens its spectrum. Monochromatic narrow band illumination at the molecule's original (unperturbed) resonant frequency yields large quenching. For the more realistic broadband illumination scenario, we calculate the final enhancement by integrating over the excitation/absorption spectrum. The numerical results indicate that the resonant illumination scenario overestimates the quenching and therefore would underestimate the total excitation enhancement if the illumination has a broader bandwidth than the molecule. Combining the excitation model with the exact Electrodynamical theory for emission, the complete realistic model demonstrates that there is a potential for significant fluorescence enhancement only for the case of a low quantum yield molecule close to the surface of the sphere. General expressions of the fluorescence enhancement for arbitrarily-shaped metal antennas are derived. The finite difference time domain method is utilized for analyzing these complicated antenna structures. We calculate the total excitation enhancement for the two-sphere dimer. Although the enhancement is greater in this case than for the single sphere, because of the derating effects the total enhancement can never reach the local field enhancement. In general, placing molecules very close to a plasmonic antenna surface yields poor enhancement because the local field is strongly affected by the molecular self-interaction with the metal antenna.Dissertation/Thesis
Ph.D. Electrical Engineering 2013
48
Chen, Ya-wen, and 陳雅文. "Study of Surface Plasmon-Enhanced Fluorescence Effects." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/51172363863220815256.
Full textAbstract:
碩士國立成功大學
工程科學系專班
97
Biosensors based on surface plasmons resonance (SPR) have been extensively researched and applied. This thesis is focused to excite surface plasmons (SPs) on metal film by using attenuated total reflection (ATR) method to enhance the local electromagnetic field. With the filed enhancement, the fluorescence molecules on the metal film are excited and then their signal is improved. Also, the lifetime change of the fluorescence molecules is discussed and indicted to the quenching effect between the fluorescence signal and the metal film. The ATR method similar to total internal reflection (TIR) method is to use light from high refractive index medium to low refractive index medium with the incident angle greater than critical angle. The light at the interface becomes into an evanescent wave, and the evanescent wave with a high k vector can excite SPs to achieve SPR when a metal thin film is inserted between the high and low refractive index media. The evanescent wave is a surface wave and only exists within few hundred nanometers from the interface. Therefore, this study is mainly to explore the factor of surface plasmon-enhanced fluorescence (SPEF) intensity with the different thickness of the dielectric layer between the metal and the fluoresce molecules. Furthermore, the excited fluorescence will transfer the fluorescent energy into the metal film to induce the change of the lifetime. The fluorescent sensor based on the SPEF can achieve the signal about 2-time enhancement compared to that of TIR fluorescence. The lifetime is increased when the thickness of the dielectric layer is increased.
49
Lee, Chih-Hung, and 李致宏. "Enhanced Fluorescence from Period Arrays of Silver Nanostructures." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/58547852946438898027.
Full textAbstract:
碩士國立中正大學
物理系
99
In this paper, we investigate and compare the fluorescent enhancement ration in the two-dimensional periodic metal structure which evaporated metal film thickness covered with fluorescent molecules. In the experiment, we use electron beam lithography to fabricate different size of the two-dimensional periodic structure, thermal evaporation process was used to produce different thickness of silver film, and the conjugate confocal microscope using fluorescence intensity measurements. In our study, found that two-dimensional periodic structure is indeed enhancement for the fluorescence, different periods have different fluorescence intensity of the structure, and the different thickness of silver film, there will be a different fluorescence intensity.
50
Huang, Yu-Xiang, and 黃昱翔. "Surface enhanced Raman spectroscopy and metal enhanced fluorescence by using silver hybrid nanostructures." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/33004271262363855399.
Full textAbstract:
碩士國立臺灣海洋大學
光電科學研究所
104
In this study, we used nanosphere lithography (NSL) and reactive ion etching (RIE) to produce a large area of periodic silver nanostructures on the glass substrate and then decorated silver nanoparticles arrays by adding nano silver particles to explore the surface-enhanced Raman scattering and metal enhanced fluorescence (MEF) effect. At first, we used atomic force microscope (AFM) and scanning electron microscope (SEM) to observe the surface of the substrates. Then we deposited SiO2 20nm in thickness on the substrates as buffer layer. Finally, we deposited fluorescent dye “DCJTB” 75 nm in thickness on the substrate and investigated its optical propoerties by using photoluminescence (PL) and time-resolve photoluminescence (TRPL). We then changed the size of silver nanoparticles and explored the effect of sizes of nanoparticle on the preformance of SERS and MEF. Experimental results shows that the absorption of different sizes of nanoparticle changes significantly. When the nanoparticle is larger, the red shift phenomenon is more obvious in absorption spetra. We observed that the PL intensity and lifetime of DCJTB was enhanced 24 times and could be shortened about 60%, respectively, as compared with those DCJTB deposted on bare glass substrate. Finally, we changed the height of the nanoparticle arrays and observed that the PL intensity and lifetime of DCJTB was enhanced 28 times and could be shortened about 62%, respectively, as compared with those DCJTB deposted on bare glass substrate. In the future, this structure can be fabricated on a flexible substrate, which is pending for further research.