Biocompatible Magnetic Hollow Silica Microspheres for Drug Delivery

A simple method for the synthesis of magnetic hollow silica microspheres is reported. Magnetic hollow silica was obtained after pretreating via precipitation method of the dextran template microspheres with magnetite. Silica shell was obtained from Na2SiO3. After thermal decomposition of the dextran template, the magnetic silica shells remained intact, as demonstrated by SEM and no evidence of dextran remnants was found according to FT-IR spectra. XRD patterns showed the formation of well-crystallized Fe3O4 and Fe2O3, even if the silica presence can be identified by FT-IR, XRD spectrum do not exhibit the formation of SiO2 network because of the very low degree of cristallinity. This material has been prepared in order to develop a magnetic drug delivery system that can be used to facilitate the targeted drug delivery of antibiotics, by testing the comparative antimicrobial activity of antibiotics themselves as well as loaded into the magnetic hollows against the suspended microbial cells. Citotoxicity studies have been carried on for the new materials by using tripan blue staining technique and eukaryotic cell cycle analysis. The obtained magnetic hollows proved to exhibit low citotoxicity levels on the HCT8 standardized cell line. The antimicrobial susceptibility assay revealed an improvement of the antimicrobial activity of the tested antibiotics on S. aureus, but not on E. coli strain. These results are demonstrating the potential use of the obtained microspheres as biocompatible antibiotic delivery and/or controlled release systems with. However, their efficiency seems to be dependent on the antibiotic structure as well as on the tested microbial strain.