Green tea extract loaded liposomes: formation, characterization and stability

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2016

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Dağ, Damla

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Polyphenol-rich green tea extract was encapsulated into liposomes using microfluidization and ultrasonication at two different mediums (acetate buffer and distilled water) to overcome the instability towards oxygen, light, temperature and alkaline conditions. The liposomes loaded with green tea extract by microfluidization were further coated with anionic biopolymers (gum arabic, whey protein) and cationic biopolymer (lysozyme, chitosan) to provide a protective layer over the liposomal surface. The stability of both uncoated and coated liposomes was explored by particle size, zeta potential, transmission electron microscopy, total phenolic content, antioxidant activity and NMR Relaxometry experiments during 28-days storage at 4°C. Moreover, in vitro digestion in the simulated gastric and intestinal juice was performed for uncoated liposomes. The results indicated the biopolymer coated liposomes showed better stability compared to uncoated liposomes during storage. Addition of lysozyme, gum arabic and whey protein to uncoated liposomes increased the particle size from 35 to 43 nm while the increase was recorded as 38 nm to 356 nm after chitosan addition. The zeta potential measurements of uncoated liposomes prepared in distilled water decreased from -30.2 to -23.2 mV at the end of 28th day. This decrease in zeta potential was eliminated by coating of liposomes with biopolymers. The biopolymer layer around the liposomes was also investigated through transmission electron microscope images. Results indicated that lysozyme, gum arabic, whey protein could provide increased stability to liposome possessing fragile structure.

Subject Keywords

Green tea., Liposomes., Biopolymers., Coating processes., Microencapsulation., Extraction (Chemistry).

URI

http://etd.lib.metu.edu.tr/upload/12621000/index.pdf
https://hdl.handle.net/11511/26476

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Graduate School of Natural and Applied Sciences, Thesis

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Citation Formats

D. Dağ, “Green tea extract loaded liposomes: formation, characterization and stability,” M.S. - Master of Science, Middle East Technical University, 2016.