Encapsulation and release of doxorubicin from silica-coated liposome

BACKGROUND: For decades, liposome drug carrier has been used to enhance drug stability and efficacy, reduce drug toxicity and adverse effects. However, they fail to provide long-term delivery due to insufficient stability. Studies have demonstrated that silica is not toxic, with chemically inert and biological compatibility, and can be used as modified material. OBJECTIVE: To characterize the silica coated liposome and investigate the controlled release property. DESIGN, TIME AND SETTING: In vitro observation. The study was performed at the Nanomedicine and Biosensor Laboratory, Biomedical Engineering Center, Harbin Institute of Technology from May 2007 to June 2008. MATERIALS: Dipalmitoylphosphatidylcholine (DPPC) was purchased from Nanjing Kangsente Chemical Engineering Company; tetraethylorthosilicate (TEOS) was purchased from Aldrich, USA. Doxorubicin (DOX) was purchased from Beijing Huafeng United Technology Company; Sephadex G-50 was purchased from Amersham Biosciences, Sweden. All other chemical agents were of analytical purity. METHODS: Liposome was formed from DPPC following the precipitation of silica by sol-gel method. MAIN OUTCOME MEASURES: Zeta-potential and dynamic light scanning were used for zeta-potential measurement and particle size distribution; transmission electron microscopy was used to collect the image of particle morphology; Fourier transform infrared spectroscopy (FTIR) was used to display chemical characteristics of Si-O-Si structure; Spectrophotofluorimetry was used to determine DOX regression equation and was further used for calculation in drug encapsulation efficiency and in vitro release. RESULTS: Circled digit oneSilica coated liposome was successfully prepared. Circled digit twoFTIR proofed the presence of Si-O-Si at 1 166, 1 080, 859 and 526 cm^-1. Circled digit threeThe DOX encapsulated silica coated liposome had encapsulation efficiency of 72.4%. Circled digit fourDrug release profiles showed that sustained release of DOX was achieved after modification of silica on liposome. CONCLUSION: With Si-O-Si as protective layer, the liposome has increased stability and prolonged drug release.