Gentamicin-loaded carbonated hydroxyapatite coatings with hierarchically porous structures: drug delivery properties, bactericidal properties and biocompatibility
Abstract
Carbonated hydroxyapatite coatings (CHACs) on titanium alloy substrates have been widely used as bone substitute materials. However, implant-associated infection becomes a serious problem in orthopedic surgery, leading to prolonged antimicrobial treatment, extensive bone debridement and failure of implants. Herein, gentamicin-loaded CHACs (Gent-CHACs) were fabricated according to the following steps: (i) the conversion of CHACs with hierarchically porous structures from calcium carbonate coatings (CCCs) by treatment with phosphate buffer solutions, and (ii) loading gentamicin into the CHACs. The main constituents in the CHACs were plate-like carbonated hydroxyapatite particles with a low crystallinity. Mesopores with a pore size of ∼3.8 nm and macropores (or apertures) with an aperture size of ∼1 μm existed within and among the plates, respectively. The hierarchically porous structures made the CHACs possess good drug loading–release properties. The sustained release of gentamicin from the Gent-CHACs inhibited significant bacterial adhesion and prevented biofilm formation against S. epidermidis (ATCC35984). In vitro cell tests indicated that human bone marrow stromal cells (hBMSCs) had good cell adhesion, spreading and proliferation on the Gent-CHACs. Moreover, the released gentamicin from the Gent-CHACs had no toxic effects on the hBMSCs. The good biocompatibility, drug delivery properties and bactericidal properties of the Gent-CHACs suggest that they have great potential as bone substitute materials.
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