Green tea extract loaded liposomes: formation, characterization and stability

Download

index.pdf

Date

2016

Author

Dağ, Damla

Metadata

Show full item record

Item Usage Stats

206
views

90
downloads

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

Collections

Graduate School of Natural and Applied Sciences, Thesis

Suggestions

OpenMETU
Core

Phase transition of chemically synthesized FePt nanoparticles under high pressure ŞİMŞEK, TELEM; Karci, Ozgur; ÖZCAN, ŞADAN (The Scientific and Technological Research Council of Turkey, 2018-01-01) We present the results of a study related to phase transformation of chemically synthesized FePt nanoparticles under high pressure from face-centered cubic into face-centered tetragonal structure. As-synthesized nanoparticles are around 4.5 nm and show superparamagnetic behavior at 300 K. After annealing under 60 bar pressure of hydrogen at 400 degrees C for 2 h, nanoparticles exhibit strong ferromagnetic behavior with 5391 Oe coercivity. Results show that high-pressure annealing lowers the decomposition te...
Trace level determination of beryllium in natural and flavored mineral waters after pre-concentration using activated carbon KILINÇ, ERSİN; Bakirdere, Sezgin; YAMAN, MEHMET (Informa UK Limited, 2011-01-01) The concentrations of beryllium (Be) in natural and flavored mineral water samples were determined by flame atomic absorption spectrophotometer (FAAS) after pre-concentration based on the complexation of Be(+2) with a mixture of acetylacetone (pentane-2,4-dione) plus morin (3,5,7,2',4'-pentaoxyflavone) and adsorption on activated carbon. The adsorbed complex was eluted with 1.5 ml of 2.0 M HNO(3) and evaporated to dryness. After adding 1.5 ml of 2 M HNO(3) and centrifuging, Be in acid solution was determine...
Active carbon/graphene hydrogel nanocomposites as a symmetric device for supercapacitors ATEŞ, MURAT; Cinar, Damla; Caliskan, Sinan; GEÇGEL, ÜNAL; ÜNER, OSMAN; BAYRAK, YÜKSEL; Candan, Idris (Informa UK Limited, 2016-01-01) Activated carbons (ACs) are successfully synthesized from Elaeagnus grain by a simple chemical synthesis methodology and demonstrated as novel, suitable supercapacitor electrode materials for graphene hydrogel (GH)/AC nanocomposites. GH/AC nanocomposites are synthesized via hydrothermal process at temperature of 180 degrees C. The low-temperature thermal exfoliation approach is convenient for mass production of graphene hydrogel (GH) at low cost and it can be used as electrode material for energy storage ap...
Nanoceria supported palladium(0) nanoparticles: Superb catalyst in dehydrogenation of formic acid at room temperature Akbayrak, Serdar; TONBUL, YALÇIN; Özkar, Saim (Elsevier BV, 2017-06-05) Highly efficient dehydrogenation of formic acid (FA) at room temperature was achieved using palladium(0) nanoparticles supported on nanoceria (Pd-0/CeO2) as catalysts. Pd-0/CeO2 was prepared by impregnation of palladium(II) ions on the surface of ceria followed by their reduction with sodium borohydride in aqueous solution at room temperature. Pd((0)/CeO2 was isolated from the reaction solution by centrifugation and characterized by a combination of advanced analytical techniques. The catalytic activity of ...
MERCURY SPECIATION BY ELECTROCHEMICAL SEPARATION AND COLD-VAPOR ATOMIC-ABSORPTION SPECTROMETRY ERGUCYENER, C; AYGUN, S; Ataman, Osman Yavuz; TEMIZER, A (1988-01-01) Mercury speciation in aqueous solutions containing inorganic mercury and methylmercury has been demonstrated using electrochemical separation prior to determination by cold-vapour atomic absorption spectrometry. Approximately 95% of the inorganic mercury was electro-deposited on a Pt electrode at –0.1 V, whereas for methylmercury –0.2 V or even more negative potentials were required. Organic mercury was determined by NaBH4 reduction after electrochemical separation. Inorganic mercury was determined in the o...

Citation Formats

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