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Artigos de revistas sobre o assunto "Biopolymers characterisation"
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John, Maya Jacob, Nokuzola Dyanti, Teboho Mokhena, Victor Agbakoba e Bruce Sithole. "Design and Development of Cellulosic Bionanocomposites from Forestry Waste Residues for 3D Printing Applications". Materials 14, n.º 13 (22 de junho de 2021): 3462. http://dx.doi.org/10.3390/ma14133462.
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This paper deals with the development of cellulose nanofibres (CNFs) reinforced biopolymers for use in packaging applications. Cellulose nanofibres were extracted from sawdust by a combination of chemical and mechanical treatments. The extracted cellulose nanofibres were chemically modified (fCNFs) and characterised by Fourier Transform Infrared Spectroscopy (FTIR). Bionanocomposites were prepared from biopolymers polylactic acid/polybutylene succinate (PLA/PBS) and cellulose nanofibres by compounding in a twin-screw extruder followed by injection moulding. The developed bionanocomposites were subjected to mechanical and thermal characterisation. As part of product development, CNF-biopolymer pellets were also extruded into filaments which were then 3D printed into prototypes. This work is a successful demonstration of conversion of waste residues into value-added products, which is aligned to the principles of circular economy and sustainable development.
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Oyekanmi, Adeleke A., N. I. Saharudin, Che Mohamad Hazwan, Abdul Khalil H. P. S., Niyi G. Olaiya, Che K. Abdullah, Tata Alfatah, Deepu A. Gopakumar e Daniel Pasquini. "Improved Hydrophobicity of Macroalgae Biopolymer Film Incorporated with Kenaf Derived CNF Using Silane Coupling Agent". Molecules 26, n.º 8 (13 de abril de 2021): 2254. http://dx.doi.org/10.3390/molecules26082254.
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Hydrophilic behaviour of carrageenan macroalgae biopolymer, due to hydroxyl groups, has limited its applications, especially for packaging. In this study, macroalgae were reinforced with cellulose nanofibrils (CNFs) isolated from kenaf bast fibres. The macroalgae CNF film was after that treated with silane for hydrophobicity enhancement. The wettability and functional properties of unmodified macroalgae CNF films were compared with silane-modified macroalgae CNF films. Characterisation of the unmodified and modified biopolymers films was investigated. The atomic force microscope (AFM), SEM morphology, tensile properties, water contact angle, and thermal behaviour of the biofilms showed that the incorporation of Kenaf bast CNF remarkably increased the strength, moisture resistance, and thermal stability of the macroalgae biopolymer films. Moreover, the films’ modification using a silane coupling agent further enhanced the strength and thermal stability of the films apart from improved water-resistance of the biopolymer films compared to unmodified films. The morphology and AFM showed good interfacial interaction of the components of the biopolymer films. The modified biopolymer films exhibited significantly improved hydrophobic properties compared to the unmodified films due to the enhanced dispersion resulting from the silane treatment. The improved biopolymer films can potentially be utilised as packaging materials.
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Gauthier, Emilie, Diane Ouwerkerk, Bronwyn Laycock e Mary Fletcher. "Biopolymer Composites for Slow Release to Manage Pimelea Poisoning in Cattle". Proceedings 36, n.º 1 (13 de fevereiro de 2020): 97. http://dx.doi.org/10.3390/proceedings2019036097.
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Cattle grazing the pastures of inland Australia can be poisoned by ingestion of certain native Pimelea plant species, particularly Pimelea trichostachya and Pimelea simplex. The Pimelea toxin, simplexin, causes often fatal restriction of the pulmonary venules, with resultant heart impacts and characteristic fluid accumulation (oedema) of the jaw and brisket regions. In certain years heavy livestock losses can occur. Currently, there is no effective vaccine or antidote for Pimelea poisoning and the only management strategy is to reduce contact between toxic plants and susceptible stock, for beef producers to avoid potentially devastating poisoning events. Nevertheless, previous research has demonstrated that prolonged low dose feeding diminished the effect in animals. It was postulated that the animal exposed to prolonged low doses developed a mechanism for detoxifying simplexin, possibly through adaptation of the rumen microbial environment. The present study seeks to investigate the use of a biopolymer/toxin composite to foster toxin-degrading microbe populations. The objectives are to manufacture biopolymer composites based on biodegradable polylactic acid (PLA), polyhydroxyalkanoates (PHAs) and/or polycaprolactone (PCL), as toxin slow-release systems for the rumen that would have broad utility across a range of plant toxins and other beneficial rumen compounds. The poster covers the manufacturing, characterisation and performance of the biopolymers in a simulated rumen environment. Preliminary results of different biopolymers/composites containing Pimelea material and toxin extracts in an in vitro simulated rumen environment for up to 30 days are presented. It was found that the release rate could be tailored by choosing the right type of biopolymer.
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Jamiluddin, J., J. P. Siregar, C. Tezara, M. H. M. Hamdan e S. M. Sapuan. "Characterisation of cassava biopolymers and the determination of their optimum processing temperatures". Plastics, Rubber and Composites 47, n.º 10 (20 de outubro de 2018): 447–57. http://dx.doi.org/10.1080/14658011.2018.1534390.
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Ang, Teik-Hun, Kunlanan Kiatkittipong, Worapon Kiatkittipong, Siong-Chin Chua, Jun Wei Lim, Pau-Loke Show, Mohammed J. K. Bashir e Yeek-Chia Ho. "Insight on Extraction and Characterisation of Biopolymers as the Green Coagulants for Microalgae Harvesting". Water 12, n.º 5 (14 de maio de 2020): 1388. http://dx.doi.org/10.3390/w12051388.
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This review presents the extractions, characterisations, applications and economic analyses of natural coagulant in separating pollutants and microalgae from water medium, known as microalgae harvesting. The promising future of microalgae as a next-generation energy source is reviewed and the significant drawbacks of conventional microalgae harvesting using alum are evaluated. The performances of natural coagulant in microalgae harvesting are studied and proven to exceed the alum. In addition, the details of each processing stage in the extraction of natural coagulant (plant, microbial and animal) are comprehensively discussed with justifications. This information could contribute to future exploration of novel natural coagulants by providing description of optimised extraction steps for a number of natural coagulants. Besides, the characterisations of natural coagulants have garnered a great deal of attention, and the strategies to enhance the flocculating activity based on their characteristics are discussed. Several important characterisations have been tabulated in this review such as physical aspects, including surface morphology and surface charges; chemical aspects, including molecular weight, functional group and elemental properties; and thermal stability parameters including thermogravimetry analysis and differential scanning calorimetry. Furthermore, various applications of natural coagulant in the industries other than microalgae harvesting are revealed. The cost analysis of natural coagulant application in mass harvesting of microalgae is allowed to evaluate its feasibility towards commercialisation in the industrial. Last, the potentially new natural coagulants, which are yet to be exploited and applied, are listed as the additional information for future study.
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Gallego, Marta, Milagros Arnal, Pau Talens, Fidel Toldrá e Leticia Mora. "Effect of Gelatin Coating Enriched with Antioxidant Tomato By-Products on the Quality of Pork Meat". Polymers 12, n.º 5 (2 de maio de 2020): 1032. http://dx.doi.org/10.3390/polym12051032.
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The use of edible biopolymers and natural additives obtained from food processing by-products is a sustainable strategy for food packaging applications. Gelatin is a biopolymer with great potential as a coating due to its low cost, high availability, and technological and functional properties. Among them, gelatin can be used as a carrier of bioactive compounds such as antioxidants, which can retard oxidation processes and thus extend the shelf-life of highly-perishable products. This study evaluated the effect of gelatin coating enriched with antioxidant tomato by-products hydrolysate (TBPH) on the quality of pork meat during cold storage. Results showed that TBPH obtained from Alcalase hydrolysis presented antioxidant activity with good stability against cooking. Additionally, chromatographic and mass spectrometry techniques, as well as in silico analysis, were used for the peptidomic characterisation of TBPH. The application of enriched gelatin coating on meat led to some physicochemical changes including increased weight loss and colour differences; however, the pH and water activity, which control meat spoilage, were maintained during storage. Moreover, coating prevented lipid oxidation of meat, and enriched-coated meat presented high antioxidant activity after cooking. These results suggest the positive role of gelatin coating enriched with TBPH in extending the shelf-life of meat during storage.
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Wongkaew, Malaiporn, Pikulthong Chaimongkol, Noppol Leksawasdi, Kittisak Jantanasakulwong, Pornchai Rachtanapun, Phisit Seesuriyachan, Yuthana Phimolsiripol et al. "Mango Peel Pectin: Recovery, Functionality and Sustainable Uses". Polymers 13, n.º 22 (11 de novembro de 2021): 3898. http://dx.doi.org/10.3390/polym13223898.
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Concerns regarding the overconsumption of natural resources has provoked the recovery of biopolymers from food processing biomass. Furthermore, the current market opportunity for pectin in other areas has increased, necessitating the search for alternative pectin resources. This is also a step towards the sustainable and circular green economy. Mango peel is the byproduct of agro-processing and has been used for high value-added components such as polysaccharide biopolymers. Pectin derived from the peel is yet to be exploited to its greatest extent, particularly in terms of its separation and physiochemical properties, which limit its applicability to dietary fiber in culinary applications. The functionality of the mango peel pectin (MPP) strongly depends on the molecular size and degree of esterification which highlight the importance of isolation and characterisation of pectin from this novel resource. This article therefore provides a useful overview of mango peel as a potential biomaterial for the recovery of MPP. Different extraction techniques and the integrated recovery were also discussed. The utilisation of MPP in different industrial schemes are also detailed out from different perspectives such as the pharmaceutical and biotechnology industries. This review convincingly expresses the significance of MPP, providing a sustainable opportunity for food and pharmaceutical development.
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Kus, B., Jaya Kandasamy, S. Vigneswaran e H. K. Shon. "Water quality characterisation of rainwater in tanks at different times and locations". Water Science and Technology 61, n.º 2 (1 de janeiro de 2010): 429–39. http://dx.doi.org/10.2166/wst.2010.824.
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Rainwater collected from ten domestic roofs in Sydney and from one in Wollongong, a town south of Sydney, Australia was analysed to determine the water quality and to compare against the Australian Drinking Water Guidelines (ADWG) to determine its suitability as a potable water supply. The pollutants analysed were 13 heavy metals, 8 salts & minerals, pH, ammonia, orthophosphate, conductivity, water hardness, turbidity, total suspended solids, Total dissolved salts & Bicarbonate. The results indicate that the rainwater tested complied to most of the parameters specified in the ADWG. Molecular weight distribution of organic matter from one of the domestic rainwater tanks was analysed in terms of the effects of aging and roof contact. Molecular weight distribution of organic matter in rainwater showed prominent peaks at 37,500 daltons may be due to biopolymers, 850 Da to humic substances, 500 Da to building blocks, 220 Da to low MW acids, and less than 220 Da to amphiphilics. The findings also indicate that the first flush volumes that by-passed the tank can have a significant influence on the water quality in the rainwater tank.
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Sabina, L., B. Kus, H. K. Shon e J. Kandasamy. "Membrane fouling propensity after adsorption as pretreatment in rainwater: a detailed organic characterisation". Water Science and Technology 58, n.º 8 (1 de outubro de 2008): 1535–39. http://dx.doi.org/10.2166/wst.2008.522.
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Organic characterisation in rainwater was investigated in terms of dissolved organic carbon (DOC) and molecular weight distribution (MWD) after powdered activated carbon (PAC) adsorption. PAC adsorption was used as pretreatment to membrane filtration to reduce membrane fouling. The MW of organic matter in rainwater used in this study was in the range of 43,000 Da to 30 Da. Each peak of organic matter consisted of biopolymers (polysaccharides and proteins), humic and fulvic acids, building blocks, low MW acids (hydrolysates of humic substances), low MW neutrals and amphiphilics. Rainwater contained the majority of hydrophilic compounds up to 72%. PAC adsorption removed 33% of total DOC. The removal efficiencies of the hydrophobic and hydrophilic fractions after PAC adsorption were 50% and 27%, respectively. PAC adsorption was found to preferentially remove the hydrophobic fraction. The majority of the smaller MW of 1,100 Da, 820 Da, 550 Da, 90 Da and 30 Da was removed after PAC adsorption. The MFI values decreased from 1,436 s/L2 to 147 s/L2 after PAC adsorption. It was concluded that PAC adsorption can be used as a pretreatment to membrane filtration with rainwater.
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Herranz, Beatriz, Wenceslao Canet, María José Jiménez, Raúl Fuentes e María Dolores Alvarez. "Characterisation of chickpea flour-based gluten-free batters and muffins with added biopolymers: rheological, physical and sensory properties". International Journal of Food Science & Technology 51, n.º 5 (6 de março de 2016): 1087–98. http://dx.doi.org/10.1111/ijfs.13092.
Texto completo da fonteTeses / dissertações sobre o assunto "Biopolymers characterisation"
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Eissa-Mohamed, Ahmed Mohamed. "Synthesis and characterisation of novel biopolymers via click chemistry". Thesis, Durham University, 2011. http://etheses.dur.ac.uk/581/.
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The work throughout is the exploitation of copper catalysed Huisgen 1,3-dipolar azide–alkyne cycloaddition, as an efficient Click reaction, for the synthesis of novel biopolymers with a broad range of potential medical/industrial applications. The strategy is to develop a powerful tool for the synthesis of libraries of materials, which will be discussed in separate chapters. Chapter one is a general introduction on biopolymers and Click chemistry with emphasis on the related literature to the present work. Chapter two involves the application of Click chemistry on model compounds; 3-methyl benzyl alcohol and phenol. The resulting products were successfully prepared via Click chemistry. NMR spectroscopy was found to be a good choice for characterisation of the resulting products. Chapter three describes the application of Click chemistry on a disaccharide compound, α,α-D-trehalose. The di-azide functionalised trehalose was synthesised by tosylation followed by acetylation and subsequent reaction with sodium azide. Different functionalities such as ester, acrylate and epoxide groups were successfully introduced via Click chemistry. NMR and FT-IR spectroscopies were found to be efficient characterisation tools to follow up the Click modification reactions. The di-acrylate functionalised trehalose showed a great potential as a cross-linker in the free radical polymerisation of HEMA to generate hydrogels. Chapter four presents the utilisation of Click chemistry to produce trehalose-based glycopolymers which have a wide range of potential applications. Biodegradable glycopolymers containing PCL or PLA were synthesised via combination of ring opening polymerisation (ROP) and Click chemistry. The ROP of lactide and ε-caprolactone, using stannous octoate and propargyl alcohol, was carried out to synthesise alkyne end capped PLA and PCL which were then coupled with di-azide functionalised trehalose by Click reaction. NMR and IR were used to prove the structure of the materials. A new class of temperature responsive glycopolymers was also synthesised via copper wire catalysed Click-polymerisation of di-azide functionalised trehalose with di-alkyne terminated PEG. The cloud point of the aqueous solution of glycopolymer was evaluated and showed an LCST at ~39 oC, known as fever temperature. In addition, the phase transition was shown to be reversible. Chapter five involves the modification of 2-hydroxyethyl cellulose (HEC) via Click chemistry. For the first time, the azide functionalisation reaction of HEC was disclosed using a one pot reaction procedure. Neutral and ionic compositions of HEC were successfully synthesised by introducing different functionalities on HEC. The compositions containing carboxylic acid or 1ry amine functionalities can be treated in basic or acidic media to give polyelectrolytes based on HEC. The compositions containing both functionalities, carboxylic acid and 1ry amine, could produce polyampholytes. Sequential Click reactions were implemented to synthesise polydimethylsiloxane (PDMS) grafted HEC as well as potentially charged functionalities. These compositions are expected to receive a great interest in personal care and cosmetics applications. Mainly, solid state 13C-NMR and FT-IR spectroscopies were used to characterise these materials. Hydrophobically and hydrophilically modified HEC were also prepared by grafting PLA, PCL or PEG onto HEC using Click coupling reaction. AFM analysis showed that some exhibit a brushlike architecture. Chapter six describes the combination of Click chemistry and ROMP to synthesise various graft polymers. Two different grafting techniques; "grafting through" (the macromonomer approach) and "grafting onto" were involved in the synthesis. The "grafting through" method involved the synthesis of oxanorbornenyl di-PEG macromonomer by Click coupling of azide terminated PEG with di-alkyne functionalised oxanorbornene. The macromonomer was then subjected to ROMP to produce PEG grafted polyoxanorbornene. Polynorbornene-g-PCL and polynorbornene-g-PEG were prepared by "grafting onto" process. This was achieved by ROMP of bromide functionalised norbornene followed by reaction with sodium azide and then Click reaction with alkyne terminated PCL and PEG. The surface analysis of these graft polymers were studied using AFM. Random graft copolymer containing PEG and PCL side chains was also prepared by ROMP of a mixture of oxanorbornenyl di-PEG and bromide functionalised norbornene followed by reaction with sodium azide and then Click reaction with alkyne end capped PCL. Chapter seven entails general conclusions and suggestions for future work.
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Grech, David. "Development of a Quasi-concertina MEMS sensor for the characterisation of biopolymers". Thesis, University of Southampton, 2014. https://eprints.soton.ac.uk/375079/.
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Rapp, Telana. "Isolation and characterisation of genes encoding biopolymer manufacturing enzymes". Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/19968.
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Thesis (MSc)--Stellenbosch University, 2012.ENGLISH ABSTRACT: Biopolymers exhibit the required material properties to replace conventional, non-biodegradable, petroleum-based polymer products. They have a closed carbon cycle, making them carbon neutral and environmentally friendly. Biopolymers are produced from non-toxic substrates during in vivo enzymatic reactions. Biosynthesis of the most commercially important biopolymers is too complex to be reproduced in in vitro reactions. Identification of the genes responsible for their biosynthesis has been under investigation, with some pathways already elucidated. The genes involved in the biosynthesis of these polymers have been targeted for genetic manipulation to increase productivity, as well as create tailor-made polymers. Novel biopolymers and the genes responsible for their synthesis are of interest for their potential commercial applications. Bacteria produce a wide range of biopolymers and are being implemented as the bio-factories for biopolymer production. They are capable of utilising easily accessible and renewable carbon sources such as sucrose for polymer biosynthesis. Bacteria thus allow for economical production of these environmentally beneficial polymers. In this study, the gene responsible for the production of an unknown biopolymer from an unknown bacterium was identified. The biopolymer producing bacteria were grown on media enriched with sucrose as carbon source, during an expression library screening in a previous study. Expression library technology was used to search for the gene and it was identified as a 424 amino acid levansucrase which had a 100% homology to Leuconostoc mesenteroides M1FT levansucrase (AAT81165.1). Biopolymer analysis revealed that the biopolymer was a levan, a polysaccharide consisting of only fructose molecules with a molecular weight of ± 5 kDa. Analysis of a 516 bp fragment of the 16S rRNA determined that the unknown bacteria were a Pseudomonas species.
AFRIKAANSE OPSOMMING: Bio-polimere besit noodsaaklike materiële eienskappe wat toelaat dat dit konvensionele, nie bio-afbreekbare, petroleum-gebasseerde polimeer produkte kan vervang. Hulle het n geslote koolstof kringloop en is dus koolstof neutraal en omgewingsvriendelik. Bio-polimere word vervaardig van nie-toksiese substrate, gedurende ensiematiese reaksies in vivo. Die belangrikste kommersiële bio-polimere se ensiematiese produksie is te kompleks om in ʼn in vitro reaksie te herproduseer. Ondersoeke tot die identifikasie van die gene wat verantwoordelik is vir die produksie van die polimere is onderweg, en sommige produksie paaie is reeds bekend. Die bekende gene word geteiken vir genetiese manipulasie om hulle produktiwiteit te vermeerder en om unieke polimere te produseer. Unieke bio-polimere en die gene wat vir hul produksie verantwoordelik is, is van belang vir hulle potentiële implimentering in komersiële toepassings. Bakteria produseer ʼn verskeidenheid bio-polimere en word as die bio-fabrieke vir polimeerproduksie geimplimenteer. Hulle kan maklik bekombare koolstofbronne, soos sukrose, gebruik om bio-polimere te produseer. Bakteria laat dus die ekonomiese produksie van hierdie omgewingsvriendelike polimere toe. In hierdie studie word die geen wat verantwoordelik is vir die produksie van ʼn onbekende bio-polimeer van ʼn onbekende bakteria, geidentifiseer. Die bakteria was gevind op media, wat verryk was met sukrose as koolstofbron, tydens ʼn vorige studie, waartydens ʼn uitdrukkingsbiblioteek gesif was op hierdie media. Uitdrukkingsbiblioteek tegnologie was gebruik om die geen te vind. Die geen was geidentifiseer as ʼn 424 aminosuur, homo-fruktose-polimeer produseerende geen, ʼn “levansucrase”. Die geen het ʼn 100% homologie met die M1FT “levansucrase” geen (AAT81165.1) van Leuconostoc mesenteroides gehad. Analise van die bio-polimeer het bepaal dat die polimeer ʼn polisakkaried was, wat slegs uit fruktose molekules bestaan het. Die molekulêre gewig van die polimeer was ± 5 kDa. Analise van ʼn 516 bp fragment van die 16S rRNS het bepaal dat die bakteria van die Pseudomonas spesie afkomstig was.
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Lees, Emma E. "Preparation and characterisation of biocompatible semiconductor nanocrystals". Connect to thesis, 2009. http://repository.unimelb.edu.au/10187/7084.
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Semiconductor nanocrystals exhibit unique optical and physical properties that make them an attractive alternative to organic dyes for fluorescent bioapplications. Although significant advances have been made since their first reported use in biology a decade ago, it still remains a challenge to prepare high quality, biocompatible semiconductor nanocrystals.In this thesis, studies are described with the aim to prepare robust, biocompatible semiconductor nanocrystals that exhibit each of the properties necessary for their implementation in biological applications. Two different approaches were investigated: ligand exchange and polymer encapsulation, and advances in each are presented. A heterobifunctional ligand suitable for bioconjugation, carboxyl terminated dihydrolipoic acid poly(ethylene glycol) (DHLA-PEG-COOH), was synthesised and characterised to prepare water-soluble, biocompatible semiconductor nanocrystals via ligand exchange. It was found that nanocrystals transferred into water using DHLA-PEG-COOH exhibit the same optical properties and colloidal stability as those prepared using DHLA-PEG. It was demonstrated that the surface charge of the nanocrystals may be controlled by altering the ratio of DHLA-PEG:DHLA-PEG- COOH ligands. In a different approach, colloidally stable, biocompatible nanocrystals were prepared via polymer encapsulation. It was found that by employing a low molecular weight polymer, biocompatible nanocrystals that exhibit a small hydrodynamic diameter could be realised.
Experimental results are presented on the conjugation of biocompatible nanocrystals to protein targets. It was found that while standard coupling chemistries yield protein-dye conjugates, these chemistries did not result in protein-nanocrystal conjugates. In order to overcome the drawbacks of standard coupling chemistries, which are susceptible to hydrolysis, a novel conjugation scheme utilising copper-free click chemistry is proposed.
Finally, the success of nanocrystals in bioapplications depends on the ability to characterise nanocrystal-protein conjugates. By means of analytical ultracentrifugation, data on the sedimentation properties of nanocrystals and nanocrystal-protein conjugates was obtained. Analysis of these data provided information on fundamental physical properties of biocompatible nanocrystals and nanocrystal-protein conjugates, in particular the core crystal size, hydrodynamic size, number of surface ligands and nanocrystal:protein stoichiometry. Such a precise, comprehensive characterisation of nanocrystals in general, and nanocrystal-protein conjugates in particular, will greatly facilitate their use in bioapplications.
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Costa, Jessica. "Use and characterisation of free or immobilised enzymatic systems for the synthesis and functionalisation of novel materials". Doctoral thesis, Università di Siena, 2021. http://hdl.handle.net/11365/1127196.
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The work reported in this Ph.D. thesis is focused on the use and immobilisation of enzymes to produce new materials, which are important for biotechnological applications.
The use of enzymes in industrial sectors is continuously increasing. Enzymes offer many advantages over traditional chemical processes. The research work of this thesis can be divided into two parts. The first part is focused on the immobilisation of laccase and chitinase. The main object of enzymatic immobilisation is to enhance the economics of biocatalytic processes. Enzymatic immobilisation allows the reuse of enzymes for an extended period of time and enables easier separation of the catalyst from the product. Furthermore, immobilisation improves many properties of enzymes: performance in the organic solvents, pH tolerance and heat stability. The most widely used immobilisation method is the covalent binding of the enzyme to support. Different type of support can be chosen for enzymatic immobilisation. As the material can plays a crucial role in the immobilisation process and the properties of the produced catalytic system. In this thesis we have chosen two different supports: super paramagnetic nanoparticles for both the enzymes used and the chitosan beads as an alternative support for chitinase. Magnetic nanoparticles show interesting properties for enzymatic immobilisation, they can be obtained with small size, increasing the yield of enzymatic immobilisation and above all, the reaction products can be easily recovered applying an external magnetic field. Magnetic nanoparticles were prepared following the traditional method of co-precipitation of Fe2+ and Fe3+ ions. This immobilisation process was successfully used for chitinase, obtaining a high immobilisation yield and increasing enzymatic stability. Different was for laccase, which having a different catalytic mechanism a revision of the synthesis has been attempt. The use of the magnetic nanoparticles obtained with the traditional method hampered the detection of stable radical species formed during the catalytic mechanism as it happens for the oxidation product of 2,2'-azino-bis (3-ethylbenzothiazolin-6-sulfonic acid) (ABTS), the standard compound used to test the enzyme activity. Changing some synthetic parameters, the new magnetic nanoparticles were produced and characterized. In fact nanoparticles with a lower aggregation state and a smaller hydrodynamic diameter were obtained and tested without any interference with the ABTS substrate. Chitinase was also immobilised on chitosan beads/Macro-Spheres (CMS), as this support is completely atoxic and so most suitable for application in food industries.The presence of active amino groups in deacetylated GlcNAc units of chitosan also enables the binding of the linker (glutaraldehyde and genipin) and then of the enzyme. The goal of this part of the thesis was to attempt the immobilisation of Chitinase on different supports, MNPs and CMS, for the efficient production of COS.
The second part of this thesis is focused on the use of enzymes to produce melanin pigments. Melanins have a variety of biological functions, including protection against UV radiation, free radical scavengers and metal ions chelators. Thanks to their properties, melanins found applications in several fields such as cosmetics, optoelectronics, food, and pharmacology. Eumelanin and Pheomelanin have been produced by oxidative enzymatic synthesis using laccase from Trametes versicolor and then characterized by the use of Multifrequency Continuos Wave (CW) and pulse Q-band EPR. Then, as soluble melanin pigments have important technological applications in different fields, like in optoelectonics, soluble pigments mimicking pyomelanin structure have been synthesized starting from Homogentisic Acid and Gentisic Acid monomers and spectroscopically characterized with their antioxidant activities determination.
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Pishbin, Fatemehsadat. "Development and characterisation of bioactive coatings based on biopolymer and bioactive glass obtained by electrochemical means". Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/11591.
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In spite of their widespread application, metallic orthopaedic prosthesis failure still occur due to lack of sufficient bone-bonding and the incidence of post-surgery microbial infections. The goal of this research was to develop multifunctional composite polymer/bioactive glass coatings as a potential strategy to improve surface properties of metallic implants. Using this approach, the bioactive glass improves osseointegration and the polymer plays a dual role: firstly to improve mechanical properties and secondly as a carrier for the release of therapeutics at the implantation site. Electrophoretic deposition (EPD) was chosen as the fabrication method, as it is a room temperature technique in which deposition properties can be effectively tuned and complex architectures can be coated homogenously. 45S5 Bioglass® (BG) powder (~10 μm) and chitosan (CS); a natural polysaccharaide (85% deacetylated); were utilised for coating AISI 316L stainless steel substrate. In aqueous EPD of CS, the electrophoretic mobility and deposition rate were shown to increase with increasing pH from 2.9 to 4.1. Aqueous EPD from BG and composite CS/BG suspensions were optimised by the Taguchi design of experiments approach. For BG suspensions, the pH and the electric field had the most and the least effects on deposition rate, respectively, and a high deposition rate of BG was attained at pH=7. For CS/BG suspensions, co-deposition was very sensitive to the concentration of BG due to its effect on suspension pH, conductivity and particles mobility. Composites with smoother surface morphology and more uniform distribution of BG particles in the CS matrix were obtained at lower glass concentrations. Structural and physical evaluations of CS and different CS/BG coatings showed that they were amorphous and also confirmed the formation of hydrogen-bonding between BG and CS in the EPD suspension. Dissolution profiles and bioactivity study of the coatings confirmed hydroxycarbonate apatite (HCA) formation in simulated body fluid (SBF) for composites in the higher range of BG loading. The bioactivity response of coatings was elucidated considering the EPD suspension preparation step and the role of surface charge on HCA formation. Tape-testing showed improvement of coating adhesion with addition of BG (for up to~ 60 wt% BG) and Vickers micro-hardness testing revealed that the composite hardness increased with the amount of BG in the films. Two types of antibacterial agents were incorporated in the composites via EPD: nano-particulate silver (Ag-np) and gentamicin (GS) antibiotic. For the first time, single step processing, in-situ formation and incorporation of Ag-np during EPD of chitosan-based composite films was shown. The release of Ag ion and GS in SBF was measured showing an initial burst release followed by a reduced release rate. Although about 40% of GS was released in 5 days, less than 7% of the loaded silver was released within 28 days. Disk diffusion tests demonstrated inhibition of S. aureus growth up to 10 and 2 days for Ag-np and GS samples, respectively. A preliminary 7 day culture study of MG-63 osteoblast like-cells on coatings indicated cellular attachment and proliferation for all coatings, except for Ag-np-containing films. The high amount of silver release was identified as the reason for cytotoxicity. Overall, the results presented in this thesis demonstrate the potential of EPD as a suitable fabrication technology for preparing multifunctional CS/BG composite bioactive coatings for orthopaedic applications.
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Ninan, Neethu. "Synthesis, characterisation and biological evaluation of tissue engineering scaffolds for wound healing". Lorient, 2013. http://www.theses.fr/2013LORIS306.
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Tissue engineering is a promising therapeutic approach that assembles cells, biomaterials, and micro-environmental factors to promote tissue repair and functional restoration. Despite many advances, tissue engineers still face significant challenges in developing artifacts to promote dermal cell growth. Scaffolds are porous artifacts that serve as extracellular matrix but are able to create the microenvironment for the growth and differentiation of skin cells and enhanced tissue development. The emerging and promising next generation of engineered tissues is relying on producing biopolymeric scaffolds containing entities like growth factors, zeolites, mesoporous silica etc. , that promote enhanced skin regeneration. The use of zeolites has been considered as a way to manipulate the host healing response at the site of injury to facilitate the tissue repair. Moreover, natural polymers accomplish a diverse set of functions in their native setting. The modern trend is to mimic extracellular matrix and the most appropriate way is to choose natural polymers which are biocompatible, biodegradable and non-toxic. The current study is the evaluation of the potential of using zeolites embedded tissue engineering scaffolds based on natural polymers for wound healing applications. We have tried to excavate the wound healing properties of different faujasites incorporated tissue engineering scaffolds using biopolymers like pectin, carboxymethyl cellulose, gelatin and hyaluronic acid by techniques like lyophilisation and solvent casting. The structural, mechanical, thermal, water uptake and in vitro degradation studies of the prepared composite scaffolds were investigated. The antibacterial activity, cytotoxicity and wound healing studies on Sprague Dawley rats were discussed in detail which state that zeolites incorporated scaffolds are suitable candidates for wound dressingL'ingénierie des tissus est une approche thérapeutique prometteuse qui rassemble des cellules, des biomatériaux et des facteurs de l'environnement pour promouvoir la réparation de tissus et la restauration fonctionnelle. Malgré beaucoup de progrès, les chercheurs font toujours face à la difficulté de conception de matériaux pour promouvoir la croissance de cellules cutanées. Les squelettes (scaffolds) sont des objets poreux fabriqués qui servent de matrice extracellulaire pour créer un microenvironnement pour la croissance et la différentiation de cellules de peau et le développement de tissus améliorés. L'utilisation de zéolites a été envisagée pour faciliter la réparation des tissus. De plus, les polymères naturels accomplissent un ensemble divers des fonctions dans leur environnement biologique. Des polymères naturels, biocompatibles, biodégradables et non-toxiques ont été choisis. Cette étude consiste à évaluer le potentiel de tissus hybrides polymères-zéolites pour la guérison de blessures. Nous avons testé les propriétés de différent taux de faujasites incorporés dans l’échafaudage polymère comme la pectine, carboxymethyl cellulose, la gélatine et l'acide hyaluronic par les techniques de lyophilisation et la voie solvant. Les études de structure, de propriétés mécaniques, thermiques et de dégradation ont été réalisées. L'activité antibactérienne, la cytotoxicité et la guérison de blessures effectuées sur des rats ont été discuté en détails
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Zhang, Lin. "Isolation and characterisation of biopolymers from anti-cancer medicinal herbs". Thesis, 2012. http://handle.uws.edu.au:8081/1959.7/564846.
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In recent years, medicinal plants have become popular for the treatment of several diseases due to their efficacy and cost effectiveness. Plant derived therapeutic agents are increasingly sought out as pharmaceuticals for the treatment of life-threatening illnesses. Important contributions have already been made in the recent years to the drug market by the compounds isolated from natural sources or from their derivatives. There is no doubt that, novel lifesaving drugs could be discovered by a systematic evaluation of ethno medicinal information using modern scientific tools.
This thesis attempts to systematically combine ethnomedicinal information together with the contemporary scientific methods to evaluate anti-cancer and other complementary properties of several traditional medicinal herbs with an aim to discover anti-cancer formulations. Other major objective of this project is to isolate and characterise potent anti-cancer agents from Traditional Chinese Medicinal (TCM) herbs.
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Hagbjer, Elizabeth. "Characterisation of Solubility and Aggregation of Alkaline Extracted Plant Cell Wall Biopolymers". Thesis, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-59110.
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Up to 30% by mass of plant cell walls are comprised of hemicelluloses. The remainder is comprised of cellulose, lignin and extractives. Potential economic uses of hemicellulose include hydrogels, fibre additives in pulp mill paper-making and as a substrate for fermentation processes. Development of a fermentation process with sugars from hemicellulose has become of increasing interest due to their potential as a feedstock for fermentation-based liquid fuels and other bio-based chemicals. These can be incorporated into existing processes, in particular alkaline chemical pulping mills, where up to 50% of the hemicelluloses are today degraded and eventually combusted. The main objective of this project is to examine the solubility and aggregation properties of xylans (the predominant hemicellulose), as this will hopefully lead to better solubility-based separations for their recovery. This was done at Michigan State University by alkaline extraction at 85°C on milled birch wood, and at 130 and 170°C (both time-dependent) on birch chips, with 50 g/L sodium hydroxide. This was then followed by precipitation/aggregation experiments with ethanol, polyDADMAC (a polycationic flocculant) and by acidification. Characterisation was done by performing dynamic light scattering (DLS) and size exclusion chromatography (SEC) analysis on resolubilised recovered material from the different extraction conditions. From these, size distributions, molecular weights and degrees of polymerization (DP) could be estimated. The DP values for the extracted polymers were higher than the expected values for hardwood xylans, owing to the incoherent SEC chromatograms. This may be due to aggregate formation with other polymers or re-solubilisation issues of the hemicellulose precipitates. The estimated size range for model xylan was between 100 to 300 nm and the ethanol precipitates seemed to also lie around this region, as detected by DLS. One of the major factors contributing to the difficulty of analysing the results was the issue of re-solubilisation of the hemicellulose precipitates and flocculates.Validerat; 20120827 (anonymous); 2017-02-08 Nedladdad 414 gånger t.o.m. september 2016. Downloaded 414 times up until september 2016 (marisr)
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Negaresh, Ebrahim Chemical Sciences & Engineering Faculty of Engineering UNSW. "Particle and macromolecular fouling in submerged membrane". 2007. http://handle.unsw.edu.au/1959.4/40743.
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Particles and macromolecular components, including biopolymers (protein and carbohydrate), are viewed as the main foulants in the complex feed submerged membrane filtration systems such as membrane bioreactor (MBR). This work focused on two aspects of fouling in complex fluids: 1- Assessing fouling propensity and mechanisms for various model solutions. 2- Using of two specific solutions modelling biomass found in MBR for a better understanding of the fouling mechanisms in submerged MBR processes. Filtrations were carried out with 0.22 ??m PVDF hollow fibre membrane. Alginate was used as a model for polysaccharide, bovine serum albumin (BSA) as a model for protein, (un)washed yeast and bentonite were representing suspended solid contents. According to the data obtained during this study the fouling propensity of each model solution was classified as follow in a decreasing order: Alginate > unwashed yeast > washed yeast > BSA > bentonite for one-component solutions; and Alginate-washed yeast > Alginate-BSA > Alginate-bentonite > Alginate-unwashed yeast for two-component solutions. Introducing the alginate increased the reversible fouling (except BSA). Passive adsorption had a significant effect on fouling of alginate even before the beginning of the filtration. Washed yeast and a mixture of washed yeast + BSA were then used as model solutions to simulate the activated sludge found in MBR. The concentration of washed yeast and BSA used in this study were calculated in order for the characterisations of the two model solution to match (in terms of biopolymer contents) those of MBR biomasses reported in the literature. By rinsing, backwashing and chemical cleaning of the membrane, three fouling layers of upper, intermediate and lower were defined respectively. Results obtained from the analysis of the biopolymers found in the cleaning solutions allow a better understanding of the fouling mechanisms occurring for the two model solutions used in this study: for washed yeast, the lower layer and for washed yeast + BSA , the upper and intermediate layers were found to have relatively high biopolymeric composition. This was explained by higher concentration of solids on the membrane surface and by higher biopolymer interactions when washed yeast was mixed with BSA.
Livros sobre o assunto "Biopolymers characterisation"
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Al-Assaf, Saphwan. Characterisation and radiation sensitivity of the biopolymer hylan. Salford: University of Salford, 1994.
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O'Brien, Paul, James Chapman, Harry Kroto, Fiona Regan e Timothy Sullivan. Nanoparticles in Anti-Microbial Materials: Use and Characterisation. Royal Society of Chemistry, The, 2012.
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Nanoparticles in Anti-Microbial Materials: Use and Characterisation. Royal Society of Chemistry, The, 2012.
Encontre o texto completo da fonteCapítulos de livros sobre o assunto "Biopolymers characterisation"
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Rajalakshmi, T. Uma, e G. Alagumuthu. "A Facile Route for the Fabrication of Nanocompositie by Effective Impregnation Through the Biopolymer Matrix and Its Characterisation". In Proceedings of the International Conference on Nanomedicine (ICON-2019), 153–61. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-25135-2_14.
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Ray Foster, Leslie John. "PEGylation and BioPEGylation of Polyhydroxyalkanoates: Synthesis, Characterisation and Applications". In Biopolymers. Sciyo, 2010. http://dx.doi.org/10.5772/10265.
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Richardson, Robert K., e Stefan Kasapis. "Rheological methods in the characterisation of food biopolymers". In Developments in Food Science, 1–48. Elsevier, 1998. http://dx.doi.org/10.1016/s0167-4501(98)80006-x.
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Ramesh, M. "Polysaccharide-Fibrous Clay Bionanocomposites and their Applications". In Advanced Applications of Micro and Nano Clay, 1–26. Materials Research Forum LLC, 2022. http://dx.doi.org/10.21741/9781644901915-1.
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Bionanocomposites are multifunctional materials, which contain biological origin and particles, have nanometer-scale dimensions (1–100 nm) and can be employed in a vast range of applications in fields like tissue engineering, electronic appliances, biosensors, regenerative medicine, drug delivery systems and food packaging due to their remarkable advantage of exhibiting biocompatibility, antibacterial activity, and biodegradability. To develop naturally biodegradable materials like bionanocomposites, several biopolymers are employed in recent years. Polysaccharides are made up of sugar molecules linked together by glycosidic bonds. These polymeric carbohydrates, which are the most prevalent polymers in nature, are gaining interests as a feasible replacement for synthetic polymers in nanocomposite materials manufacturing. Polysaccharides are promising matrix for the production of green nanocomposites due to their biodegradable nature and biocompatible qualities, hierarchical structure, and high film-forming ability. This chapter discusses the processing, properties, characterisation, and applications of bio-based nanocomposites with various polysaccharides functionalized by various nanofillers.
Trabalhos de conferências sobre o assunto "Biopolymers characterisation"
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Pesce, Cecilia, Giovanni Pesce, Marco Molinari e Alan Richardson. "Customising Microstructural and Mineralogical Characteristics of Hydrated Lime Using Biopolymers". In 4th International Conference on Bio-Based Building Materials. Switzerland: Trans Tech Publications Ltd, 2022. http://dx.doi.org/10.4028/www.scientific.net/cta.1.353.
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The study of lime-based systems is vital to the design of new sustainable building materials. Air lime (calcium hydroxide, Ca (OH)2) is a binder that has attracted considerable attention for its ability to capture CO2 from the atmosphere, its low-cost and low-energy production process. Furthermore, Ca (OH)2 is an important phase of hydrated Portland cements, and lime-based mortars have shown high elasticity and the ability of self-healing. The performance of lime-based building materials can be enhanced by the addition of organic compounds that can modify the mineralogy and microstructure of Ca (OH)2. In this study, the effects of four biopolymers including starch, inulin, pectin, and calcium lignosulfonate, on the microstructure and mineralogy of lime have been investigated. Hydrated lime was produced by slaking quicklime in water. Two sets of hydrated lime batches were produced for each polymer: (i) the polymer was previously dissolved in water and subsequently mixed with lime, and (ii) the polymer was added as a dry powder to the already hydrated lime at the end of the slaking process. Characterisation of the batches was performed using scanning electron microscopy, X-ray diffraction and laser diffraction. Results indicate that biopolymers affect the nucleation and growth of Ca (OH)2 crystals. This influences the microstructure and crystal aggregation of hydrated lime in colloidal suspension, which will have important implications on the use of biopolymers in Portland cement applications and in the use of lime as a binder for mortars.