Nanoporous delivery system to treat osteomyelitis and regenerate bone: Gentamicin release kinetics and bactericidal effect

Conventional treatment of osteomyelitis involves the repeated surgical removal of dead bone tissue coupled with repeated irrigation of the wound and prolonged systemic administration of antibiotics. Therapy of bone infections could easily last the rest of the patient's life because of the poor accessibility of the infection site by common systemically administered antibiotics. The objective of the present study is to develop a novel bone bioactive resorbable nanocomposite that can serve as a delivery system for antibiotics. We synthesized three different samples of porous bioactive resorbable silica-calcium phosphate nanocomposite (C3S1, C1S1, and C1S3) that has the ability to provide a sustained release of effective dose of gentamicin for 28 days. Porosity measurements showed that the average pore diameter of C3S1, C1S1, and C1S3 samples is 44.8, 54.4, and 70.9 nm, respectively. Moreover, the silica-rich composite (C1S3) is characterized by a significantly higher surface area (155.8 m(2)/g) than the silica-poor samples (C3S1) (42.9 m(2)/g). For all samples, the release profile study showed initial burst release followed by a sustained release of gentamicin. The released gentamicin has a strong inhibitory effect on Staphylococcus aureus bacteria. In addition FTIR analysis showed the formation of a biological apatite layer on the material surface after 24 h of immersion in simulated body fluid. Results of the study suggest that the silica-calcium phosphate nanocomposite can serve as a delivery vehicle for gentamicin to treat osteomyelitis and regenerate bone. (c) 2005 Wiley Periodicals, Inc.