Preparation And Characterization Of Lysozyme-Released Nanoparticles And Chitosan Nanocomposite Scaffold

In order to solve the problems of slow degradation and poor mechanical properties of chitosan tissue engineering scaffold, this paper constructs a nanocomposite chitosan scaffold which is made of lysozyme-released nanoparticles and chitosan using nanosize loading drug technology and nanocomposite technology. The nanoparticles in the scaffold can not only release lysozyme to accelerate the degradation of chitosan because lysozyme is able to degrade the chitosan, but also markedly enhance the mechanical properties of chitosan.Firstly, lysozyme-released nanoparticles were originally prepared by means of an ionic gelation process of chitosan (CS) and tripolyphosphate (TPP) on mild condition, and the influence of experimental conditions on the characteristics of nanoparticles was studied. Results showed that the spherical chitosan nanoparticles were 50-300nm in diameter. The loading capacity was from 1.6% to 11.4% which was larger than the other microspheres containing lysozyme, the encapsulation efficiency was from 4.6% to 47.3%, and the cumulative release ratio in vitro ranged from 55% to 100% in two weeks. The relative activity of lysozyme in all the samples was maintained 85% above during the release in vitro which meant the nanoparticles could protect the lysozyme well. The first order dynamic model could describe the release process in vitro perfectly.Secondly, the influence of rehydrating conditions on the properties of scaffold and activity of lysozyme was studied. Results showed that the 2.5 % (v/v) ammonia was the best condition in our research.Thirdly, the nanocomposite chitosan scaffolds which was made of lysozyme-released nanoparticles and chitosan matrix were originally constructed and the characteristics of nanocomposite with various percentages of nanoparticles were studied. SEM showed that the scaffold had a regular appearance and the holes were interconnected. SEM/EDX indirectly showed the nanoparticles dispersed well in the scaffold. The porosity was above 90%. The mechanical properties were markedly enhanced. The degradation rate increased with the increasing of nanoparticle content.