DRUG DELIVERY WITH POROUS SILICON FILMS, MICROPARTICLES, AND NANOPARTICLES

Porous silicon (PSi) is a nanostructured biomaterial that has received considerable attention for use in a wide variety of biomedical applications, including biosensing, bioimaging, tissue engineering and drug delivery. This interest is due to several key physical and optical properties of PSi, including easy fabrication of porous structure, the ease of surface chemistry modification, excellent in vivo biocompatibility, and very low toxicity. With tuning of these properties PSi has successfully been used for the delivery of a variety of therapeutics, ranging from small-molecule drugs to larger peptide/protein-type therapeutics and various anticancer drugs. Drug delivery system of PSi has been developed for mainly two reasons: controlled drug delivery to reduce toxic side effects and to increase oral bioavailability of poorly soluble drugs. The loaded drug releases from porous matrix by either pore diffusion or porous matrix dissolution depending on the pore size and surface chemistry of PSi. This paper reviews the fabrication of PSi by electrochemical etching and other means, and further, surface modifications by oxidation, hydrosilylation, and thermal carbonization. The drug loading into PSi by spontaneous adsorption, covalent attachment, and physical adsorption followed by in vitro and in vivo release of different drug molecules have then been reviewed.