Novel impurity-free hexagonal hydroxyapatite nanotubes for local delivery of antibiotics in orthopedic surgery: in vitro release validation.

Hydroxyapatite (HA) has been studied recently as a drug carrier in prevent implant infections due to its biocompatibility and osteoconductive properties, but most of these studies failed to control infection. The aim of the present study was to evaluate the potential of this impurity-free novel HA nanotube as a carrier for drug delivery in a controlled manner. Gentamicin was selected as an antibiotic to study the drug-carrier properties of this novel HA nanotube. Gentamicin was introduced into the HA nanotubes through immersion and evaporation process. Gentamicin-loaded HA nanotubes were then placed in phosphate buffered saline (PBS) and drug release profile was then monitored by measuring free genntamicin in the solution. An initial burst release of the drug occurred in the first 24 hours; subsequently, 84.7% of the drug was released from the nanotubes in 9 days. After 13 d, the concentrations of released drug were measured close to 2 μg/ml. The porosity of the gentamicin-loaded HA nanotubes was also observed using a Hitachi s-4800 high-resolution SEM, further confirming the drug-carrier property of HA nanotubes. Our novel bone substitute is an effective prophylactic tool for the local delivery of gentamicin to prevent periprosthetic infections.