Enhancing the biological activity of chitosan and controlling the degradation by nanoscale interaction with bioglass.

A nonuniform degradation of physical mixture of organic-inorganic biomaterials increases their risk of failure. In this study a chemical bonding between chitosan and bioglass was used as an alternative product to address this issue. To prepare a homogenous composite, chitosan was functionalized with γ-glycidoxypropyl trimethoxysilane and chemically bonded with bioglass during sol-gel method. The gelation time of these hybrids samples was optimized by varying parameters such as composition of chitosan and temperature. It was shown that gelation time was reduced from 7 days for pure bioglass at 25°C to less than six minutes at 70°C for chitosan 40 vol % bioglass hybrid. Furthermore, the enzymatic degradation after 4 weeks was decreased from 80% mass loss for pure chitosan to 32% for chitosan 40 vol % bioglass hybrid. The results of in vitro study demonstrated that the presence of nanoscale interaction enhanced the bioactivity of chitosan. Additionally, hybrid scaffolds were fabricated with pore sizes in the range of 200-400 µm. These scaffolds were prepared by the addition of sodium bicarbonate during sol-gel method as a gas foaming agent and a neutralizer that resulted in decreasing the gelation time of hybrids to less than three minutes. The hybrids fabricated in this study possessed superior characteristics compared to chitosan, also physical mixture of chitosan-bioglass and are promising alternatives for bone tissue engineering applications.