| Chitosan is widely used as a base material of tissue engineering scaffold fabrication due to its excellent biocompatibility, biodegradability, nutritional function and pharmacological efficacy. But the degradation rate of chitosan in vivo is difficult to adjust to match the building rate of a new tissue regeneration. In this paper, a new idea, named self-controlled degradation, is employed by using the Controlled Drug Delivery System, which can control the degradation rate of chitosan scaffold by controlled release of lysozyme from the microparticles. By using this new way, we can obtain a novel intervening therapeutic and self-controlled biodegradable scaffold, which may solve the degradation problem of chitosan in tissue engineering application.Firstly, we prepared microparticles by mean of a water-in-oil-in-water technology. The basic operating parameters were determined and three separation ways, including a direct vaccum freeze-drying method, a filtration method and a centrifugation method, were investigated on the influence of morphological properties of PLGA microparticles. Results showed that the direct vacuum freeze-drying method (one step method) could prepare the microparticle-dotted fibriform network, which was a new idea in constructing some microparticle-combined polymer based scaffolds. We then described and explained the microparticle formation mechanism from different angles.Secondly, we probed into the influence of experimental conditions on the characteristics of PLGA microparticles. The results showed that the yield was between 5.7% to 97.4%, the diameter was from 30μm to 100μm, the encapsulation efficiency was from 40% to 90%, partly could achieve 95% above. The controlled release efficacy was obvious, the cumulative release ratio ranged from 20% to 70%. Most importantly, the enzyme remained its specific activity above 90%. We then mimicked the in vitro release by using mathematic models. The first order dynamic... |
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