| Liposome as a novel delivery system, has been widely applied in pharmaceutical, cosmetical and food industry. However, it suffers a lot of problems including self-aggregates, easy drug leakage from the system, which severely limits the application of liposome. Nowadays, researchers proposed modification of liposome through several ways to improve the properties of liposome, such as surface modification by sediment of polyelectrolyte outside the liposome, preparing innovative liposomes with new characteristics by lipid derivatives, etc. In this paper, tea polyphenol(with great bioactivity, embracing anti-oxidation, anticancer, anti-inflammatory, etc. what’s more, it is easy to be detected) was chosen as the core material. Tea polyphenol nanoliposome(TPN) was obtained by combining ethanol injection with dynamic high-pressure microfluidization method. Through following modification, the traditional modification liposome chitosan-liposome(CH-TPN) was obtained by chitosan. Furthermore, based on CH-TPN, a new type of modified liposome silica-chitosan-liposome(S-CH-TPN) was acquired. Further investigation on the modification theory was conducted, along with the effect of modification material on the structure as well as the bioavailability of tea polyphenol liposome.TPN showed an average size of 101.3±1.49 nm, zeta value of-10.59±0.35 mV, and the modified samples CH-TPN, S-CH-TPN based on it exhibited an average diameter about 231.83±0.57 nm, 573.6±2.89 nm, respectively, and zeta value of 12.65±0.04 mV, 7.82±0.28 mV, respectively. All of the three samples displayed small PDI value, which means uniformity system. The determination of size and zeta confirmed the successful coat of modification layer outside the liposome. Further analysis about interaction mechanism between modification materials and lipsome was showed, that CH-TPN embraces fluffy appearance with chitosan coat on the liposome like patches, meanwhile, the hydrophobic structure of chitosan inserted into the liposome membrane. S-CH-TPN possessing tighten modification layer by the electrostatic interaction between silica and chitosan, along with the dehydration by Si-OH and the hydroxyl of chitosan.By FTIR, Atomic force microscope(AFM), transmission electron microscope(TEM), surface tension and rheological analysis, the change of structure after modification was obtained. It was observed that the existence of modification material brought new functional groups along with the disappearance of some functional groups. Obviously, the modification materials bond with the membrane of liposome, meanwhile, the hydrogen interaction was formed. Both the AFM and TEM images confirmed that the CH-TPN modification layer coated on surface of liposome, and the structure formed in S-CH-TPN held up the morphology of liposome by improving the structure rigidity. Surface tension and rheological properties showed that the membrane rigidity and fluidity was influenced by presence of chitosan and silica.The tea polyphenol releasing profiles in PBS buffer solution after liposome modification indicated that CH-TPN displayed the obvious sustained release result of 21.5±1.37% was released in 12 h. Furthermore, S-CH-TPN exhibited the highest DPPH scavenging activity in vitro antioxidant experiment, and the reducing power of the three samples showed the similar situation.In vitro digestion of continuous gastric and intestinal juice as well as the single intestinal juice showed that CH-TPN always maintained the best stability under gastric juice, and CH-TPN showed the best protection effect on EGCG(one of the constituents in tea polyphenol), while S-CH-TPN showed the best protection effect on ECG(anther constituents in tea polyphenol). The two different kind of digestion modules showed that gastric digestion will affect the digestion under the following intestinal juice. |
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