Natural nanoporous silica frustules from marine diatom as a biocarrier for drug delivery

The possible use of natural silica nanoporous biomaterial from marine diatom for drug delivery applications was explored. Coscinodiscus concinnus have a homogeneous size distribution with radius of 220 ± 15 µm with surface featuring a mounded topography with about 2 µm wide porous domes organized on the surface in pentagonal packing. Streptomycin, used as a hydrophilic drug to demonstrate the in vitro oral drug delivery model based on diatom structure, mainly adsorbed on to the diatom silica surface (foramen), inside pores (cribrum) and into the internal hollow diatom structure (cribellum). The maximum drug loading capacity of streptomycin was 33.33 ± 2 %. The release was biphasic, involving initial burst release (first 6 h) mainly from the surface of diatom foramen, and sustained drug release (upto 7 days) from cribrum and cribellum. The study indicated that the live diatoms from marine environment, due to their unique features (easy cultivable, low-cost and biocompatibility), are a potential and alternative natural source of nanoporous siliceous material for in vitro oral drug delivery applications.