Hydroxyapatite/nifuroxazide conjugate: Characterization, drug release and antimicrobial activity

Synthetic hydroxyapatite (Ca-10(PO4)(6)(OH)(2), HAp) is very similar to the inorganic part of the bones and teeth of mammals. It is a well-known biomaterial with good biocompatibility, osteoconductivity and bioactivity. Nifuroxazide (C12H9N3O5, NFX) is a broad-spectrum antibacterial drug and poorly soluble in water. In order to increase the solubility of NFX, nano-sized HAp powder and raw NFX drug were mixed giving, as a result, a HAp/NFX conjugate. Characterization of the raw materials and the obtained conjugate confirmed the integration of NFX on the HAp surface. An in vitro study of drug release in simulated stomach acid and intestinal fluid showed a much faster release of NFX from HAp surface than those of the raw drug. The HAp/NFX conjugate showed excellent inhibitory effects against Gram-positive bacterium Staphylococcus aureus, Gram-negative bacterium Escherichia coli and yeast Candida albicans, proving the nano-sized HAp powder as a promising drug carrier.