Antibiotic delivery potential of nano- and micro-porous marine structure-derived β-tricalcium phosphate spheres for medical applications

Abstract

Aims: This study gives a detailed evaluation of the antibiotic potential of a marine structure-based new drug delivery system produced by hydrothermally converting foraminifera exoskeletons to β-tricalcium phosphate (β-TCP) to treat clinical strain Staphylococcus aureus (MW2). Materials & methods: Foraminifera precursor materials were hydrothermally converted at 250°C for 48 h to produce β-TCP and loaded with gentamicin sulfate by adsorption for 24 h. The physicochemical properties of the material were characterized by scanning electron microscopy, powder x-ray diffraction and for pore size distribution profiles. The antibacterial efficacy of the system was tested for inhibition of S. aureus growth and in vitro cellular behavior were tested with human osteoblast cells (MG63) for cell viability. Discussion: Pore size distribution profiles showed that the structure allows the uniform distribution of nanopores of 1.5 nm and micropores of approximately 5 µm. The in vitro release profile indicates an initial burst release of 5% of total incorporated gentamicin. A time-delayed antibacterial efficacy test was designed to introduce the bacteria at predetermined time intervals from 0 to 60 min and showed that gentamicin prevents S. aureus grown in the same culture within 30 min, with no evidence of bacterial regrowth within 24 h. Human osteoblast cell (MG63) studies showed no detrimental effect on cell viability. Conclusion: In the light of these results nano- and micro-pores containing β-TCP spheres show promise as potential bone void filler particles with antibacterial effects. Original submitted 7 February 2013; Revised submitted 9 May 2013