Antisolvent precipitative immobilization of micro and nanostructured griseofulvin on laboratory cultured diatom frustules for enhanced aqueous dissolution

We report for the first time an antisolvent synthesis of nanostructured hydrophobic drug formulation onto a natural diatom. The jewel of the sea, a marine diatom, which is enriched in silicon, was cultured and grown in the laboratory. Its frustules were isolated and purified. The polar functional group on its surface provided unique physical and chemical properties. Griseofulvin (GF), an antifungal drug was used as a model compound was precipitated onto and adsorbed onto hydrophilic diatom surface, while stabilizer hydroxypropyl methyl cellulose (HPMC) was used for restricting particle growth during the composite synthesis. This work demonstrates that the fine drug crystals incorporated onto the diatom silica surface. The structural and morphological properties of the drug was characterized by various techniques. The drug loading of the formulation was estimated to be 41 % by weight. The incorporation of micro/nano crystals on the diatom surface dramatically enhanced the dissolution rate, and lowered the time required for 50 % dissolution for pure drug from 240-58 min for the drug composite, and the time required for 80 % dissolution or T-80 was found to be 180 min for the composite while the pure drug reached a maximum of 65 % in 300 min.