Preparation And Properties Of Silica/Gelatin Hybrid Microspheres

Drug-loaded gelatin microspheres is widely used in arterial chemo-embolization because of its biocompatibility, biodegradability and nontoxicity. But gelatin can rapid dissolve and biodegrade in water and mechanical properties were bad, which resulted in fast drug release, and application limited. Silica not only has the properties of non- dissolved in water and rigidity , but also can interact with gelatin by hydrogen bonding, so silica can modify the disadvantage of gelatin hybrid microspheres in"burst release", drug release time and mechanical properties. We prepared the 5-Fluorouracil loaded silica/gelatin hybrid microspheres with in-situ hydrolysis cheap sodium silicate as SiO₂ precursor, and studied the drug content, drug encapsulation efficiency and in vitro release at the same time, this work is very significant in theories and applications.Emulsion chemical-crosslinking method is used to prepare blank gelatin microspheres(GMs). The impacts on morphology ,recovery and diameter of the GMs were studied, such as the concentration of gelatin, water phase/oil phase ratio, emulsifier HLB value and concentration, emulsification time and crosslinking time. The results showed that the blank GMs was 36.8μm in mean size, smooth in spherical surface and recovery was 94.5%, when gelatin concentration was 0.20g/ml, water phase/oil phase ratio was 1/10, gelating time was 60min, emulsifier HLB value was 6, emulsifier concentration was 0.5%, emulsion time was 20 minutes, crosslinking time was 1 hour.Based on the preparation of blank GMs, the impact on the preparation of drug loaded GMs is studied, and the GMs mean size, drug content and drug encapsulation efficiency, and finally on the release profiles of the encapsulated drugs were determined. The results showed that 5-Fu gelatin microspheres was 63.9μm in mean size, drug content was 31.62%, drug encapsulation efficiency was 94.86%, and the in vitro release of drug loaded GMs shows the in vitro release model suit to Higuchi model.In order to modify gelatin dissolution, drug encapsulation and drug release, the silica/gelatin hybrid microspheres were prepared by in-situ hydrolysis. The effects of hydrolyzed time, the content of sodium silicate and the kinds of alkali on the mean size, drug content and drug encapsulation efficiency were studied, and morphology of hybrid microspheres were examined with scanning electron microscopy(SEM). The results showed that silica/gelatin hybrid microspheres can improve the drug encapsulation efficiency, restrain the"burst release"and prolong drug release time; the mean size of the hybrid microspheres was 5.4μm, drug content was 20.52%, drug encapsulation efficiency was 61.57%. The hybrid microspheres have promising used in arterial chemo-embolization therapy of liver cancer.