| Medium-chain fatty acids (MCFAs) include octanoic acid and decanoic acid. Compared with long-chain fatty acids (LCFAs), MCFAs can be metabolic quickly and efficiently, they can enhance the heat production and oxygen consume, thus reduce body weight. However, MCFAs possess poor water solubility and not so stable, which make it a hurdle for its oral route application. If take it directly, it may bring uncomfortable to the gastrointestinal tract. Liposomes, as a new sustained and controlled release carrier, can be a solution to this problem. Furthermore, the application of polymer to coat on the surface of liposomes could efficiently improve the stability of liposomes. The dissertation investigated the preparation, physical and chemical properties, storage stability and in vitro release of carboxymethyl chitosan (CMCS) coated MCFAs nanoliposome (Coated-LP) and the uncoated conventional MCFAs nanoliposomes (Un-LP).Experiments were carried out to optimize the preparation parameters of conventional MCFAs nanoliposome by Film evaporation-DHPM method. The best condition was:PC concentration was1.0g/100mL, PC:Cholesterol was5:1, MCFAs concentration was4.0mg/mL, PC:Tween80was10:3; process pressure by DHPM was120MPa with2passes. The so obtained Un-LP sample had EEMCFAs of87.3%, size was66.8nm. Coated by CMCS, the adding method was selected from CMCS to Un-LP and the opposite, which shows no difference, finally, the Un-LP adding to CMCS method was chosen. The best CMCS coated MCFAs liposome (Coated-LP) was obtained when CMCS:PC was2:3(W:W).Then the characterization of Un-LP and Coated-LP was conducted by observation which showed both are homogenous and transparent. By measuring the morphology by TEM and AFM, which showed they both have fine global and uniform. The size of Un-LP was around60nm, while the Coated-LP was around100nm. Size detected by DLS of the Un-LP and Coated-LP were69.8nm and101.5nm, respectively. Zeta potential were-3.09and-22.08mV, respectively. FTIR showed that hydrogen bonding was occurred between CMCS and Un-LP. Results got from DSC indicated the transition temperature of Un-LP was51.14℃, which increased to139.34℃for Coated-LP. It thus can be conclude Coated-LP possess higher stability than Un-LP from results discussed above. The EEMCFAs of Coated-LP (74.36±9.35%) was a little smaller than that of Un-LP (80.26±5.14%). The pH values of them were both at the range of7.33to7.56.Stored for90days, the size, PDI, turbidity, pH, MCFAs retention ratio was all determined at certain time intervals. It was found that all the samples showed better stability under4℃than that of25℃. Coated with CMCS can slow down the oxidation and hydrolytic of PC and the aggregation of liposomes.In vitro release study found Coated-LP had very obviously sustained-release than Un-LP. They both went through a burst and they slow release in SGF, slow release at first and then speed up in SIF. The final release ratio of MCFAs in Un-LP was84.10±3.32%and64.10±3.02%in Coated-LP.In conclusion, the Coated-LP prepared by Film dispersion-DHPM with coated by CMCS exhibited more favorable properties than Un-LP. It improved the stability and exhibited better sustained-release. Thus, CMCS coated MCFAs nanoliposome has potential to be MCFAs carrier. |
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