Dissertations / Theses on the topic 'NaYbF4'

Die hier vorgelegte Dissertation beschäftigt sich mit Untersuchungen an nanoskopischen Emittern und den Möglichkeiten, deren Fluoreszenzverhalten durch kontrollierte Ankopplung an photonische und plasmonische Strukturen zu beeinflussen. Zum einen werden mit Ytterbium- und Erbium-Ionen kodotierte NaYF4 -Nanokristalle untersucht, die hervorragende Eigenschaften bei der Umwandlung von niederenergetischen Photonen in solche höherer Energie besitzen. Das so entstehende Fluoreszenzlicht einer Ansammlung von Nanokristallen wird auf seine Abhängigkeit von der Anregungsintensität untersucht. Mit der Hilfe eines Rasterkraftmikroskops (AFM) wird eine Abhängigkeit der spektralen Zusammensetzung des Fluoreszenzlichts einzelner Nanokristalle von deren Größe im Bereich von wenigen bis 50 nm aufgezeigt. Durch gezielte Manipulation mit dem AFM werden ebenfalls einzelne Nanokristalle an Goldnanokügelchen gekoppelt und die Mechanismen der beobachteten plasmonischen Verstärkung der Emission durch zeitaufgelöste Messungen analysiert. Einzelne Stickstoff-Fehlstellen-Zentren in Nanodiamanten werden in einem zweiten Themenkomplex als Einzelphotonenquellen eigesetzt. Diese werden durch den Einsatz einer Nahfeld-Sonde auf Mikrokugel-Resonatoren aufgebracht, wodurch die Emission aufgrund der Ankopplung an die Flüstergalerie-Moden der Kugeln die typischen, scharfen Überhöhungen im Spektrum aufweist. Diese Methode lässt sich nicht nur verwenden, um zwei oder mehr Emitter an die selben Resonanzen einer Kugel zu koppeln. Es ist auch möglich, die Kugeln in einem Vorbereitungsschritt zu charakterisieren, und so kann insbesondere eine spektrale Übereinstimmung zwischen einer der Resonanzen und dem Emitter erreicht werden. Desweiterne wird demonstriert, wie durch die Kopplung an eine plasmonische Antenne aus Goldnanokugeln mittels AFM auch die Effizienz der Einzelphotonenquelle gesteigert werden kann.<br>The topic of the dissertation presented here is the investigation of nanoscopic emitters and the possibilities to influence their fluorescence behavior by controlled coupling to photonic and plasmonic structures. NaYF4 nanocrystals codoped with ytterbium and erbium are investigated since they provide excellent properties in upconverting of low-energetic photons to photons with higher energy. The fluorescence light that is generated in this process of a small cluster of nanocrystals is investigated on its dependence on the excitation intensity. With the help of an atomic force microscope (AFM) a dependence of the spectral composition of the fluorescence light from single nanocrystals on their size ranging between a few to 50 nm is demonstrated. By selective manipulation with the AFM, individual nanocrystals are coupled to gold nanospheres and the mechanisms of the observed plasmonic amplification of the emission is analyzed with time-resolved measurements. Single nitrogen–vacancy centers in nanodiamonds are employed as single-photon sources in a second subject area. A near-field probe is employed to attach these single quantum systems to microspherical resonators, by which their emission features the typical peaks in the spectrum due to the coupling to the whispering gallery modes of the spheres. This method can not only be applied to couple two or more single-photon emitters to the very same modes of a microsphere, but the resonators themselves can be pre-characterized to match one of the modes with the emitter. Furthermore, it will be demonstrated how the efficiency of a single-photon source can be enhanced by coupling the nitrogen-vacancy center to a plasmonic antenna made of gold nanospheres.

Sphere and star shaped NaYGdF4:Yb/Er(Tm) upconversion nanoparticles were successfully synthesized utilizing a methanol assisted thermal decomposition approach and their chemical, spectroscopic and fluorescence properties were fully characterized. In addition, their influence on the spectroscopic and fluorescence properties of two phthalocyanines (Pcs) (unsubstituted tetrathiophenoxy phthalocyanine (H2Pc) and aluminium octacarboxy phthalocyanine (Cl)AlOCPc) was investigated. Upconversion nanoparticles were found to produce characteristic upconversion fluorescence emissions in the blue, green, red and NIR regions and were also shown to possess paramagnetic properties. Simple mixing with an H2Pc in toluene was found to exert no change on the spectroscopic or fluorescence properties of the Pc while covalent conjugation to a (Cl)AlOCPc resulted in a large Q band blue shift accompanied by a decrease in fluorescence lifetimes in DMSO. The red light excitation mediated singlet oxygen generation of the H2Pc mixed with upconversion nanoparticles was investigated and singlet oxygen fluorescence lifetimes were found to decrease in the presence of the nanoparticles. Upconversion mediated singlet oxygen generation, by way of resonance energy transfer to the Pc, was also attempted using 972 nm excitation; however, no singlet oxygen was detected utilizing singlet oxygen NIR emission detection. Pending further work using alternative singlet oxygen detection methods, this suggests that while upconversion nanoparticles possess excellent fluorescent imaging capabilities, they are relatively inefficient in inducing singlet oxygen production simply when mixed with phthalocyanines. Despite this, by combining phthalocyanines and upconversion nanoparticles, we present a system capable of: multimodal imaging, using both upconversion and phthalocyanines emissions, singlet oxygen generation, via direct excitation of the phthalocyanine with red laser light, and, possibly, magnetic resonance imaging, as a result of doping the upconversion nanoparticles with Gd3+ ions.

La spectroscopie de fluorescence induite par laser a ete utilisee pour analyser les intenses emissions de l'ion pr 3 + dans les fluorures k 2yf 5 orthorhombique et nayf 4 hexagonal. L'utilisation conjuguee de la spectroscopie resolue dans le temps et de la variation de temperature a permis d'identifier et d'attribuer les niveaux electroniques des ions pr 3 + dans chacun des materiaux apres excitation dans le bleu ( 3p 0 ou 3p 1) ou dans le rouge ( 1d 2). Les repartitions spectrales se correlent assez bien avec les symetries des sites cristallographiques de l'yttrium sur lesquels entrent en substitution les ions pr 3 +. Deux conversions par transfert d'energie entre ions pr 3 + ont ete identifiees. L'une, stokes, bleu-rouge induisant le peuplement du niveau 1d 2 par relaxation croisee apres pompage dans le bleu, plus favorablement dans le niveau 3p 1. L'autre, anti-stokes, rouge-bleu produisant une emission bleue a partir du niveau 3p 0 apres pompage dans le niveau 1d 2. L'analyse des evolutions temporelles des emissions stokes et anti-stokes sous excitation selective pour diverses concentrations a permis de proposer des chemins de desexcitation et de transfert permettant d'expliquer les conversions observees et d'evaluer les parametres les regissant. L'efficacite importante des mecanismes de transfert entre ions pr 3 + dans k 2yf 5 comparativement a nayf 4 a ete attribuee au caractere unidimensionnel de la structure qui induit une topologie de distribution non aleatoire favorable a l'existence de paires ou d'agregats d'ions pr 3 +. La signature de ce type d'entites semble se traduire par l'apparition de structures de faible intensite de part et d'autre des transitions spectrales principales. Enfin, des phases du systeme naf-(y, yb, pr)f 3 ont ete preparees par coprecipitation et presentent des proprietes similaires a celles de leurs homologues preparees par ceramisation ; avec cependant une quasi-absence de centres impuretes oxygene.

<p>The discovery, formulation, and characterization of novel compositions of matter for aid in the diagnosis and treatment of disease has ever been a compelling force behind nanomaterials development. In instances of disease originating from oncogenic mutation, proliferation, and metathesis; cancer has long been a most difficult dysfunction to diagnosis and treat in virtue of its innate alteration and disregulation of otherwise well-managed and healthful cellular processes. To date, cancer therapies have relied largely on highly toxic chemotherapy or radiation treatments, addressing the overarching problem of individual cellular mutations in a global sense, often deleterious to the overall health of the patient. Ever-progressing work on nanomaterial-based applications to either promote cancer diagnosis or implement novel therapeutic means of drug delivery, activation, or the precisely-targeted destruction of cancer cell lines has been afforded much attention in the integrated biological and materials science fields. Recent developments in nanosized laser materials incorporating lanthanide-doped sensitizer and activator pairs and the development of numerous crystallographic, co-dopant, morphological, and/or surface-appended optimizations to these materials have given rise to a novel class of nanomaterials, with unique photophysical properties that have direct import into light-based activation of chemical processes, triggered non-invasively through biological tissues, and merging intra-cellularly targetable nanocrystalline compositions and ex vivo light activation. Upconverting nanocrystals (UCNCs) are one such class of nanomaterial wherein near-infrared (NIR) light, at the nadir of tissue absorption, can serve to sequentially or cooperatively excite long-lived lanthanide (Ln3+) 4f excited states and, through various energy transfer processes coupled between both the UCNC material composition and its integral Ln3+ dopants, are capable of building an excited state population capable of emitting in higher frequencies than its incident NIR excitation.</p><p>In the study of these UCNCs, the prospect of activating intra-cellular photodynamic processes or drugs of low cellular toxicity, until light activated in a precisely localized regime (e.g. the nucleus of a cell), has motivated extensive research into the generation of novel UCNC materials, in multiple compositions and on multiple size scales to direct the mechanisms of upconversion (UC) to produce high fluence ultraviolet (UV) photons upon NIR (972 nm) excitation. Continuing optimizations have yielded a high ytterbium (Yb) sensitizer, cubic &#945;-NaYbF4 UCNC composition, codoped with a thulium activator, to generate excited state saturated UV transitions, 1I6 &#8594; 3F4 (349 nm) and 1D2 &#8594; 3H6 (362 nm), and their refinement to afford dominant UV emissive spectral signatures at low NIR laser excitation. Their photophysical dynamics are sparsely described in the literature, breaking from both fields of laser photonics and conventional inorganic nanoscience, and require renewed emphasis to be afforded in exacting crystallographic, photophysical, and size dependent effect characterization, heavily directing the structure-function relationships of luminescent Ln3+ dopants and their host crystal matrices. Requisite in this study is a call for the optimization of uniform, monodisperse, and reproducible preparations of unique UCNCs and precise characterization of the properties they display and the origins thereof.</p><p>Offered herein are the enveloping efforts to more fully understand the mechanistic processes of UC of both poorly characterized, literature standard materials, novel UCNCs tuned for enhancement of UC emission in the UV, and the adaptations to each that ultimately affect their photophysical dynamics. A tandem course of this research follows from inorganic shelling, passivation methodologies to ameliorate crystallographic surface defects and UC luminescence quenching sites to overall enhance the dominant UV emissivity of novel co-doped UCNC. These state-of-the-art UC materials are: 1) &#945;-NaYbF4: Tm3+, interlaced with gallium, chromium, yttrium, and other trivalent metal ions, serving to finely modulate UC mechanistic processes and enhance luminescent properties and 2) sodium co-doped LaF3 and BaLaF4 (0.5%Tm, 20%Yb), displaying 3 and 2 orders of magnitude enhancement of UV emissions due to controlled perturbation of the local crystal field environment. The Core @ Shell architectural derivatives of these materials exhibit an eminent departure from classical luminescent fluorophores, phosphors, or quantum confined luminescent nanomaterials, in both degree of luminescent flux generation and the complicated mechanistic processes they are derived from.</p><p>To a great extent, this work attempts to establish testable grounds for comparison of UCNCs; extending from interrogation of photophysical lifetime measurements, excitation versus emissive flux power dependence studies, high resolution X-ray photoelectron spectroscopy (HR-XPS) and power diffraction (HR-XRD) assessments of crystallographic defects and perturbations on the atomic scale, and the establishment of new metrics of radiant flux versus absolute quantum yield for use in comparison of UCNCs towards their applicability in areas of variable or limited excitation flux and the ultimate utility of discerning hit-to-lead UCNC materials for medical nanodevice compositions. A salient component affecting these metrics is the direct surface interactions with respect to solvents, coordinating ligands, and appended functional moieties for enhancement of UCNCs towards specific applications; largely directed towards cancer biology and medical study. In a confluence of inquisition of UCNCs and their high energy, UV luminescent properties, interfacing with the surface presenting effects of solublization and bio-targeting molecular functionalization; literature standard, &#946;-NaYF4 (2%Er, 20%Yb) UCNCs have been generated in highly uniform compositions to assess the size-dependent effects with respect to luminescent quenching surrounding a UCNC surface and functionalization methodologies have been offered as a proof of concept towards the construction of an optimized biomolecular targeting nanodevice, with known limits and predictable interactions, both to NIR excitation light and potential intra-cellular biological environments.</p><p>The ultimate goal of these explorations is the innovative fusion of the above concepts into a nanotherapeutic device involving: 1) the generation of a well-studied and predictable NIR-absorbing and dominant UV-emissive UCNC, with defined co-dopant optimizations and employing an optimal Core @ Shell architecture, 2) the requisite surface functionalization needed to afford aqueous solubility and a means of covalently conjugating targeting molecules of interest, and 3) the ultimate and equal assessment of such a composite system with respect to possible alternate materials in the literature and novel UCNCs currently under development. To date, no such convergent study has been conducted to any degree of reproducibility or certainty of desired and defined functionality. In this work is described in detail each optimized component for such a device or potentially one marked by differing, but assessable conditions for alternate applications. The optimization of a sub-10 nm, dominant UV-emissive UCNC, the crystallographic and photophysical origins of its UC mechanism under varied conditions, and the optimal means of their employment (both in terms of establishing equivalent metrics and utility in cancer nanotherapeutics), assessment, and readdressing of, as yet undiscovered limits to these materials are presented.</p><br>Dissertation

Nanopartikel auf Basis von NaYF4 erfreuen sich großer Beliebtheit durch ihre vielseitigen Einsatzmöglichkeiten. Durch die Dotierung mit Ytterbium und Erbium im Wirtsgitter ist es beispielsweise möglich, niedrigenergetisches Infrarotlicht in höher-ergetisches, sichtbares Licht umzuwandeln. Zudem lässt sich NaYF4 auch im Nanometermaßstab präparieren, sodass ein Einsatz in Zellen oder lebenden Organismen möglich ist, wo die zur Anregung verwendete infrarote Strahlung ohne Probleme das Gewebe durchdringen kann. Zu Beginn dieser Arbeit zeigten aufwärtskonvertierende Nanomaterialien wie NaYF4 :Yb,Er jedoch auch nach Umhüllen mit einer inaktiven Schale aus undotiertem NaYF4 nur sehr geringe Lumineszenz-Quantenausbeuten und kurze Energieniveau-Lebenszeiten. Im Rahmen dieser Arbeit wurde die Synthesemethode zur Herstellung von aufwärtskonvertierenden NaYF4 -Nanopartikeln durch den Einsatz neuer Eduktmaterialien modifiziert und die Auswirkung der Modifikationen auf die Partikeleigenschaften näher untersucht. So konnte gezeigt werden, dass durch den Einsatz einer alternativen Fluoridquelle (NaHF2) Partikel mit sehr engen Partikelgrößenverteilungen hergestellt werden können. Jedoch zeigte sich auch, dass die mit NaHF2 präparierten Partikel sich nicht mit einer Schale aus undotiertem NaYF4 umhüllen ließen. Im zweiten Teil dieser Arbeit wurde daher der Fokus auf die Verbesserung der optischen Eigenschaften gelegt. Durch die Verwendung von getrockneten Lösungsmitteln und wasserfreien Seltenerdacetaten, sowie NH4F als Fluoridquelle gelang es erstmals, aufwärtskonvertierende Kern/Schale-Nanopartikel (<50 nm) mit einer sehr hohen Lumineszenz-Quantenausbeute, ähnlich dem des makrokristallinen Referenzmaterials, herzustellen. Auch bei sehr kleinen Kern/Schale-Partikeln (≤15 nm) konnten Quantenausbeuten erzielt werden, die nur um einen Faktor 3-4 niedriger sind als beim Referenzmaterial. Dabei zeigte sich durch die Messung der Energieniveau-Lebenszeiten, dass die größten Verlustprozesse durch die Yb3+ Emission bei 940 nm auftraten und diese durch aufbringen einer Schale unterbunden werden konnten.

碩士<br>國立成功大學<br>材料科學及工程學系<br>105<br>Up-conversion, a photoluminescence process which converts few low energy photons to a higher energy photons, has more potential usages in many different fields like bio-imaging, solar spectrum tuning, and security encoding. Nowadays, researches about up-conversion mainly concentrating on synthesis of nanoparticles to improve inefficient situation for viable implementation. In this Perspective, we use the low temperature of the hydrothermal method in the synthesis process successfully. The morphology of NaYF4 is controlled by the reaction mechanism under series of pH value condition, and the luminescence intensity is further changed. As a result, we observe a sample with a low pH value had a better luminous intensity than a sample with a higher pH value. In addition, we describe that the local symmetry disorder around the rare-earth ions was caused by Li+ doping in host lattice. Local symmetry disorder is the reason for enhancement of photoluminescence. NaYF4 material doped with higher concentration of Li+ has stronger photoluminescence properties and intensity than its corresponding un-doped Li+ group. The NaYF4 absorb the infrared light into the blue-violet luminescence, so that the energy absorption of the aquatic is increased to enhance photosynthesis effect and reach the green energy application.

碩士<br>國立屏東大學<br>應用物理系碩士班<br>106<br>In recent years, upconversion nanoparticle attracted lots of researcher. Because of it have unique optical properties. After absorb low energy light the High-energy light is emitted by a variety of conversion mechanisms. Also UCNP shows well stable property in complex chemical environment. Thus scientist identified it as a material that can be stably present in living organisms. Some of the paper also proof that UCNP is low toxicity in organism. In last decade, UCNP developed since NaYF4 crystal. After that scientist doped rare earth element in UCNP, they found out doped RE element can make crystal structure change from cubic crystal to hexagonal crystal. Not only so, they also found out the light intensity of hexagonal phase crystal is higher than cubic phase structure. 　　Why the luminous efficiency of hexagonal phase crystal UCNP can several times higher than cubic phase crystal. After measured by Raman spectroscopy found in Raman spectrum of hexagonal phase structure the intensity also several times higher than cubic phase structure. This phenomenon indicates that the hexagonal crystal structure is more stable than the cubic crystal structure. 　　In this paper, the main research direction is the temperature-varying Raman spectroscopy of upconversion nanoparticles, and the Raman spectroscopy of hexagonal crystals is analyzed to compare the difference of oscillating peaks under different temperature environments.

In dieser Arbeit ist das Wachstumsverhalten von unter 10nm großen, aufwärtskonvertierenden NaYF4-Nanokristallen der hexagonalen und kubischen Phase untersucht worden. Die Ostwald-Reifung solcher Partikel in Ölsäure/1-Octadecen führt zu einer Verbreiterung der Partikelgrößenverteilung, falls das Kolloid nur aus Partikeln einer Kristallphase besteht. Eine schmale Teilchengrößenverteilung tritt nur dann auf, wenn die Partikel der b-Phase in Anwesenheit eines Überschusses von Partikeln der a-Phase wachsen. Solche binären Gemische aus Partikeln der a- und b-Phase entstehen, sobald Kolloide aus Partikeln der a-Phase für eine genügend lange Zeit erhitzt werden, denn bei hohen Temperaturen nukleieren Keime der b-Phase nach einer gewissen Zeit. Weil durch die Anzahl der Keime die finale Partikelgröße des Produkts der b-Phase bestimmt wird, ist eine Kontrolle der Nukleation wichtig um die finale Partikelgröße steuern zu können. Es wird gezeigt, dass die Anzahl der Keime der b-Phase stark abhängig von der Zusammensetzung der Partikel der a-Phase ist, die als Ausgangsmaterial verwendet werden. Die a-Phase ist dafür bekannt Na1−xYF4−x-Mischkristalle mit Zusammensetzungen von x=0 bis x=4/9 zu bilden. Bei natriumarmen Partikeln der a-Phase entstehen eine geringe Anzahl an Keimen der b-Phase, wobei Partikel der a-Phase mit einem hohen Gehalt an Natrium eine große Anzahl an Keimen bilden. Durch die Ausnutzung dieser Abhängigkeit und der dementsprechenden Modifizierung der Synthese der Partikel der a-Phase, können in Ölsäure/1-Octadecen kleine, phasenreine b-NaYF4:Yb,Er-Partikel mit Größen von unter 6 nm, sowohl als auch deutlich größere Partikel erhalten werden. Weiterhin wird gezeigt, dass Mischungen von a- und b-Partikeln auch sehr gut für die Synthese von Kern/Schale-Partikeln geringer Größe geeignet sind. Durch die Reaktion von Natriumoleat, Seltenerdoleat und Ammoniumfluorid werden zunächst etwa 5nm große b-NaYF4:Yb,Er-Kernpartikel gebildet, wobei ein hohes Verhältnis von Natrium- zu Seltenerdionen die Nukleation einer großen Anzahl von Keimen der b-Phase begünstigt. Anschließend wird eine etwa 2nm dicke Schale aus b-NaYF4 aufgewachsen, wobei 3–4nm große a-NaYF4-Partikel als Vorläuferpartikel für das Schalenmaterial dienen. Im Gegensatz zu den Kernpartikeln werden diese Partikel der a-Phase jedoch mit einem geringen Verhältnis von Natrium- zu Seltenerdionen hergestellt, welches die unerwünschte Nukleation von b-NaYF4-Partikeln während des Schalenwachstums wirksam unterdrückt. Diese neue Methode zur Herstellung sehr kleiner aufwärtskonvertierender Kern/Schale-Nanokristalle kommt ohne zusätzliche Kodotierung der Kernpartikel aus und liefert Partikel im Gramm-Maßstab.

碩士<br>國立成功大學<br>化學工程學系碩博士班<br>101<br>In this thesis, graphite oxide was synthesized by modified Hummers method and then reduced and surface modified with L-arginine via the microwave method to yield the well-dispersed reduced graphene oxide at first. Secondly, the NaYF4:Yb, Er nanoparticles with near infrared (NIR) upconversion fluorescence imaging property were synthesized, surface coated with silica nanoshells, and then further modified with 3-(triethoxysilyl)propylsuccinic anhydride to generate carboxylic groups on the surface of silica nanoshells. Finally, they were covalently bound on the arginine-modified reduced graphene oxide to form the nanocomposite combining the functions of NIR upconversion fluorescence imaging and photothermal therapy. By transmission electron microscopy (TEM), atomic force microscope (AFM), X-ray diffraction (XRD), Fourier transform infrared spectrometry (FTIR), Raman spectra, electron spectroscopy for chemical analysis (ESCA), UV/VIS/NIR spectrophometer, and fluorescence spectrophotometer, the products’ morphologies, sizes, crystalline structures, and optical properties were characterized. It was found that the formation of reduced graphene oxide, NaYF4:Yb,Er nanoparticles, and their nanocomposite has been achieved successfully. In addition, by using a HeLa cancer cell line, it was demonstrated this nanocomposite indeed possessed both the functions of NIR photothermal therapy and fluorescence imaging.

Melanoma is one of the most aggressive types of skin cancer with a high mortality rate. Therefore, there has been an increasing demand for new therapeutic approaches to counteract such elevated rates. Hyperthermia is a therapeutic approach that works by raising the temperature inside of the tumour, ranging between 41 and 45 ºC. The temperature increase may disrupt the biochemical processes of the tumour cells, which in turn can translate into cellular death either by apoptosis or necrosis. However, this promising therapeutic therapy has some hurdles, especially regarding the homogeneous distribution of heat throughout the tumour. Because of the limitations of this technique, there is a need to create new ways of applying it with higher efficiency. Nanoparticles can be used to induce hyperthermia, and they have the upside of being able to be fine-tuned in order to specifically target the tumour and apply heat from inside-out. Various types of nanoparticles have been used to generate hyperthermia, but more recently upconversion nanoparticles (UCNPs) have garnered a lot of interest due to their unique characteristics. The objective of this work was to develop the groundwork needed to apply hyperthermia by using UCNPs. To achieve this objective four different melanoma cells lines were used, MNT-1, B16-F10, A375 and SK-MEL-28, along with 2 different types of UCNPs, NaYF4:Yb,Er(20/2%)@mSiO2 (NaYF4UCNPs@mSiO2) and Gd2O3:Yb,Er (Gd2O3UCNPs). Prior to every assay, both types of UCNPs were dispersed in ultrasound bath for 20 minutes. Physicochemical characterization of nanoparticles was performed by dynamic light scattering (DLS) for NaYF4UCNPs@mSiO2 nanoparticles size and morphology was also assessed by Scanning transmission electron microscopy (STEM). DLS results of Gd2O3UCNPs showed high values of hydrodynamic diameter and polydispersity index, indicating agglomeration of the nanoparticles. Furthermore, zeta potential showed a low value, indicating the instability of the nanoparticles and tendency to aggregate. DLS results of NaYF4UCNPs@mSiO2 showed acceptable values of hydrodynamic diameter, with low values of polydispersity index indicating a more uniform size of nanoparticles. Zeta potential of NaYF4UCNPs@mSiO2 indicate that they have incipient stability at 25 μg/mL, and lower stability at 100 μg/mL. STEM imaging and analysis indicated size of 77.78 ± 3.53 nm. Cytotoxicity of both UCNPs were tested by WST-8 protocol, with Gd2O3UCNPs being tested on MNT-1 and A375 cell lines, and NaYF4UCNPs@mSiO2 being tested on the four cell lines mentioned above. In both cases, cells were exposed to 12,5, 25, 50, 100 and 200 μg/mL of UCNPs. Gd2O3UCNPs caused a decrease in the viability of A375 at the highest concentrations after 48 hours of exposure, compared to the control group. NaYF4UCNPs@mSiO2 caused a decrease in cell viability for all cell lines for 100 and 200 μg/mL after 24 and 48 hours, with MNT-1 cells also having a decrease of viability at 25 and 50 μg/mL for 48 hours after the exposure. A375 cells have a decrease of viability for 50 μg/mL at 48 hours after the exposure. Cellular uptake of NaYF4UCNPs@mSiO2 only happened on MNT-1 and SK-MEL-28 cell lines. Hyperthermia sensitivity profile of MNT-1 and A375 cell lines was performed by exposure to 43 and 45 ºC during 30, 60 and 120 minutes, and cell viability measured 24, 48 and 72 hours after exposure through the MTT assay. In almost every case MNT-1 cell viability decreased with the increase of exposure time where, after 120 minutes of exposure, cell viability was below 60% for all the exposure times in both of the tested temperatures. Comparatively, A375 cells exposed to 43 ºC did not have viability lower than 60% in all cases. Finally, MNT-1 cells exposed to 45 ºC for 120 minutes showed viability values below 20% after 48 and 72 hours, while on the other hand, A375 cells viability ranged from 40 to 60%, depending on the exposure time. This work allowed to set a range of concentrations of UCNPs that can be used without compromising cell viability, being good candidates for near-infrared induced hyperthermia to melanoma cells. This work also allowed to conclude which temperatures and exposure times to apply in order to potentiate the effect of hyperthermia in melanoma cells. The conditions defined in the current work (UCNPs concentrations and temperatures) can be replicated to generate near-infrared light-triggered hyperthermia in melanoma cells using UCNPs.<br>O melanoma é um dos tipos de cancro da pele mais agressivos e com uma alta taxa de mortalidade. Portanto, tem havido uma demanda crescente de novas abordagens terapêuticas para neutralizar taxas tão elevadas. A hipertermia é uma abordagem terapêutica que atua ao aumentar a temperatura dentro do tumor, desde 41 a 45 ºC. O aumento da temperatura pode interromper os processos bioquímicos das células tumorais, que por sua vez pode se traduzir em morte celular por apoptose ou necrose. No entanto, apesar de promissora, a hipertermia tem alguns obstáculos, especialmente manter uma distribuição homogênea de calor por todo o tumor. Devido às limitações desta técnica, há necessidade de criar novas formas de aplicá-la com alta eficiência. As nanopartículas podem ser usadas para induzir hipertermia, e têm a vantagem de poderem ser ajustadas especificamente para o tumor, e dessa forma aplicar calor de dentro para fora do tumor. Vários tipos de nanopartículas têm sido usados para gerar hipertermia, mas, mais recentemente, as nanopartículas de conversão ascendente (UCNPs) têm atraído muito interesse por causa das suas características únicas. O objetivo deste trabalho foi desenvolver as bases necessárias para aplicar a hipertermia usando UCNPs. Para atingir este objetivo, quatro linhas de células de melanoma diferentes foram utilizadas, MNT-1, B16-F10, A375 e SK-MEL-28, juntamente com 2 tipos diferentes de UCNPs, NaYF4:Yb,Er (20/2%)@mSiO2 (NaYF4UCNPs@mSiO2) e Gd2O3:Yb,Er (Gd2O3UCNPs). Antes de cada ensaio, ambos os tipos de UCNPs foram dispersas num banho de ultrasons durante 20 minutes. A caracterização físico-química das nanopartículas foi realizada por espalhamento dinâmico de luz (DLS) para NaYF4UCNPs@mSiO2 tamanho das nanopartículas e morfologia também foi avaliada por microscopia eletrónica de transmissão de varrimento (STEM). Os resultados de DLS de Gd2O3UCNPs mostraram altos valores de diâmetro hidrodinâmico e índice de polidispersidade, indicando aglomeração das nanopartículas. Além disso, o potencial zeta apresentou baixo valor, indicando a instabilidade das nanopartículas e tendência de agregação. Os resultados de DLS de NaYF4UCNPs@mSiO2 mostraram valores aceitáveis de diâmetro hidrodinâmico, com baixos valores de índice de polidispersidade indicando um tamanho mais uniforme de nanopartículas. O potencial zeta de NaYF4UCNPs@mSiO2 indica que eles têm estabilidade incipiente a 25 μg/mL e estabilidade inferior a 100 μg/mL. A imagem e análise STEM indicaram tamanho de 77.78 ± 3.53 nm. A citotoxicidade de ambos os UCNPs foi testada pelo protocolo WST-8, com Gd2O3UCNPs sendo testados nas linhas celulares MNT-1 e A375, e NaYF4UCNPs@mSiO2 sendo testados nas quatro linhas celulares mencionadas acima. Em ambos os casos, as células foram expostas a 12,5, 25, 50, 100 e 200 μg/mL de UCNPs. Gd2O3UCNPs causou uma diminuição na viabilidade de A375 nas maiores concentrações após 48 horas de exposição, em comparação com o grupo de controle. NaYF4UCNPs@mSiO2 causou uma diminuição na viabilidade celular para todas as linhas celulares para 100 e 200 μg/mL após 24 e 48 horas, com as células MNT-1 também tendo uma diminuição da viabilidade em 25 e 50 μg/mL por 48 horas após a exposição. As células A375 têm uma diminuição da viabilidade para 50 μg/mL em 48 horas após a exposição. A internalização das NaYF4UCNPs@mSiO2 só aconteceu nas linhas celulares MNT-1 e SK-MEL-28. O perfil de sensibilidade à hipertermia das linhagens celulares MNT-1 e A375 foi realizado pela exposição a 43 e 45 ºC por 30, 60 e 120 minutos, e a viabilidade celular medida 24, 48 e 72 horas após a exposição por meio do ensaio MTT. Em quase todos os casos a viabilidade celular MNT-1 diminuiu com o aumento do tempo de exposição onde, após 120 minutos de exposição, a viabilidade celular ficou abaixo de 60% para todos os tempos de exposição em ambas as temperaturas testadas. Comparativamente, as células A375 expostas a 43 ºC não tiveram viabilidade inferior a 60% em todos os casos. Por fim, as células MNT-1 expostas a 45 ºC por 120 minutos apresentaram valores de viabilidade abaixo de 20% após 48 e 72 horas, enquanto, por outro lado, a viabilidade das células A375 variou de 40 a 60%, dependendo do tempo de exposição. Este trabalho permitiu definir um intervalo de concentrações de UCNPs que podem ser usados sem comprometer a viabilidade celular, sendo bons candidatos para hipertermia induzida por radiação próxima do infravermelho para células de melanoma. Este trabalho também permitiu concluir quais temperaturas e tempos de exposição aplicar para potencializar o efeito da hipertermia em células de melanoma. As condições definidas no trabalho atual (concentrações e temperaturas de UCNPs) podem ser replicadas para gerar hipertermia desencadeada por radiação no infravermelho próximo em células de melanoma usando UCNPs.<br>Mestrado em Biologia Aplicada

碩士<br>國立中正大學<br>物理系研究所<br>105<br>The present work reports super-intensifying enhancement in the upconversion emission of Tm3+ in NaYF4 host matrix, via a two strategies, (a) fabrication of Nd3+-doped upconversion nanoparticles (UCNPs) with multilayer core-shell structure (NaYF4:Yb,Tm@NaYF4:Yb,Nd@NaYF4) and (b) deposition of Nd3+-doped UCNPs on the surface of low refractive index resonant waveguide grating (RWG) in aqueous environment. Firstly, a highly luminescent 795 nm excited Nd3+-doped upconversion nanoparticles (UCNPs) is synthesized to overcome the overheating effect and significantly improve the penetration depth in tissues, comparing with the conventional Yb3+-doped UCNPs, thus being more feasible for many applications in biology. Furthermore, their upconversion luminescence (UCL) is enhanced about four times under 795nm excitation, as against the traditional 980 nm irradiation. More important, as the Nd3+-doped UCNPs coating on a low refractive index resonant waveguide grating (RWG) in aqueous environment, the up-conversion luminescence signal is greatly enhanced. We achieved an enhancement factor up to 103 fold for the UCL from rare earth-doped nanoparticles, when the RWG was illuminated under a near IR laser (980 or 795nm) with an incident angle matching with the guided mode resonance angle of the RWG. Therefore, the UCNP-doped low refractive index RWG platform can be extended for potential biomedical applications. Keywords : Up conversion、Nd3+-doped、Core-shell、Guided mode resonance、Low-refractive index。

Nanopartikel (NP) finden in immer mehr Produkten des täglichen Lebens Verwendung, werden im Tonnenmaßstab produziert und werden so auch zunehmend in die Umwelt gelangen. Man weiß sehr wenig über die Wechselwirkungen von synthetischen NP mit der Umwelt, insbesondere mit Pflanzen. Bislang ist weitestgehend unbekannt, ob, wie und mit welcher Geschwindigkeit NP aufgenommen und im Pflanzenkörper verteilt werden. In dieser Arbeit wird die Aufnahme und Verteilung von NP in verschiedenen Pflanzenarten untersucht. Besonderes Augenmerk wurde dabei auf die Aufnahmekinetik der NP gelegt. Die Untersuchungen wurden mit polydispersen und monodispersen NP verschiedener Größen (15 nm und 30 * 60 nm) durchgeführt. Um die Aufnahme verfolgen zu können, wurden für die Untersuchung NP verwendet, die den optischen Effekt der Aufwärtskonversion zeigen (englisch: Upconversion luminescent nanoparticles (UCNP)). Hierbei handelt es sich um NaYF4-NP der hexagonalen Kristallstruktur dotiert mit Yb3+ und Er3+. Die Upconversion Lumineszenz ist ein nichtlinearer optischer Prozess, bei dem die Absorption von zwei oder mehr Photonen längerer Wellenlänge (ca. 974 nm) zur Emission eines Photons kürzerer Wellenlänge (blau, grün und rot) führt. Die UCNP lassen sich als Multifunktionsmarker einsetzen, da sie mittels Fluoreszenzmikroskopie, Elektronenmikroskop und Röntgenfluoreszenzspektroskopie nachweisbar sind. Im Rahmen dieser Arbeit wird eine neue Synthesemethode von hexagonalen NaYF4:Yb20%,Er2%-NP vorgestellt. Hierbei werden 2 bis 4 nm große NaYF4:Yb20%,Er2%-NP der kubischen Kristallstruktur als einzige Monomerquelle (Opferpartikel) bei der Synthese der NaYF4:Yb20%,Er2%-NP der hexagonalen Kristallstruktur verwendet, wobei die Opferpartikel in einem Ölsäure enthaltenden Lösungsmittel aufgeheizt oder in dieses bei hoher Temperatur (> 300 °C) injiziert werden. Mit Hilfe der Opferpartikelsynthese lassen sich hexagonale NaYF4:Yb20%,Er2%-NP im Grammmaßstab unter Kontrolle der Größe, Phase und Form herstellen. Neben monodispersen NP mit definierten Größen lassen sich Kern-Schale NP herstellen, die eine starke Steigerung der Fluoreszenzintensität zeigen.

There are several factors which conspire to limit the efficiency of solar cells. One of these is the fact that a solar cell is unable to absorb photons of energy less than the band gap of the semiconductor from which it is made; in the case of some high-band gap materials such as amorphous silicon – the model system used in this study – this can mean that as much as 50% of the solar spectrum is unusable. Upconversion phosphors – materials which can, by way of two or more successive photon absorptions, convert low energy (typically near infrared) light into high energy (typically visible) light – offer a potential solution to this problem as they can be used to convert light, which would otherwise be useless to the cell, into light which can be used for power generation. In this thesis we work towards the application of NaYF4-based upconverters to enhanced efficiency amorphous silicon (a-Si) photovoltaic power generation. We begin by synthesizing these upconverters at a range of temperatures and studying the crystallographic and spectroscopic properties of the resulting materials, elucidating heretofore undocumented trends in their luminescence and crystallography, including the effect of synthesis temperature on upconversion intensity, crystallite size, and lattice parameter. We also investigate the emission quantum yield of these materials, beginning with an in depth discussion and investigation of two methods for recording absolute quantum yields. We demonstrate that the quantum yields of the materials may vary by a factor of over 100, depending on the synthesis conditions. After we have fully characterized these properties we turn our attention to the application of these materials to amorphous silicon solar cells, for which we provide a proof of concept by demonstrating the effect of upconversion luminescence on the photoconductance of an a-Si film. We conclude by developing a roadmap for future improvements in the field.

碩士<br>國立中正大學<br>物理系研究所<br>106<br>Highly luminescent 793 nm excited Nd3 +-doped up-conversion nanoparticles (UCNPs) have shown great promise in bio-applications, benefiting from the high tissue penetration depth and low tissue overheating effect at 793 nm. Furthermore, as the Nd3+-doped UCNPs are deposited on a low refractive index resonant waveguide grating (RWG) in aqueous environment, UCL generated from the UCNPs can be greatly enhanced thanks to the guided mode resonance (GMR) enhanced excitation field atop of the RWG. Therefore, the combination of UCNPs bioprobe and low refractive index RWG can be a good platform for biosensing applications. Human cardiac troponin I (cTnI) is considered to be the gold standard for the diagnosis of myocardial infarction due to its presence only resulting from direct damage of myocardium. Herein, we synthesize Nd3+-doped UCNPs with multilayer core-shell structure (NaYF4:Yb,Tm@NaYF4:Yb,Nd@NaYF4) as sensitive upconversion luminescence (UCL) bioprobes, and developed a sensitive extended sandwich-type strategy for the detection of human cardiac troponin I (cTnI) with the help of GMR effect. The limit of detection calculated to be around 0.0254 pg/ml could meet the requirements for clinical application, and it can be used for early diagnosis of AMI.

碩士<br>國立中正大學<br>物理系研究所<br>105<br>In this study, we investigate the enhancement effect of upconversion fluorescence (UCF) emission of low refractive index resonant waveguide grating (RWG) via streptaviin-biotin affinity binding to enhance upconversion luminescence of lanthanide-ion (Ln3+) doped upconversion nanoparticles (UCNP). We fabricate one dimensional grating structure consists low refractive index porous silica (n = 1.22) by using nanoimprint lithography process subsequent depositing of high refractive index thin film (TiO2) on the surface of the sample. By drop coating NaYF4:Yb3+,Tm3+ nanoparticles conjugate Streptavidin on the biotinylated RWG structure, we demonstrate the UCF can be enhanced by factor of up to the 103 when excitation resonance is achieved compared to the UCNP@SA on the flat area surface. Furthermore, via affinity binding between biotin-streptavidin interaction, the UCF can be enhanced due to the high density of UCNP on the RWG structure much more 5-fold, 7-fold and 9-fold than non-labeled sample including: non-biotinylated, non-streptavidin and non-biotin-streptavidin. The enhancement UCF can be used in into the biomedical application, especially as a biomarker for targeted tumor imaging. Keywords: Rare-Earth, Upconversion, Fluorescence, Low Refractive Index, Guided Mode Resonance, Biotin-Streptavidin