Biomimetic matrix mediated room temperature synthesis and characterization of nano-hydroxyapatite towards targeted drug delivery

Abstract

The nucleation and growth of hydroxyapatite is closely associated with the extracellular matrix environment. Bovine serum albumin, collagen and polyvinyl alcohol were used to mimic the extracellular matrix. An attempt to understand the role of these matrices on the synthesis and function of hydroxyapatite has been made. XRD, FT-IR, XPS, TG-DTA, SEM and TEM confirmed the formation of hydroxyapatite synthesized by the biomimetic route. Further, the role of the organic matrix in controlling the nucleation and growth of hydroxyapatite particles at the nano level is understood by in-depth analysis of the XPS spectra. The in vitro release of the anti-cancer drug methotrexate in aqueous solution was studied, and the in vitro release profile was assayed by elution in phosphate buffered saline with pH 7.4 and pH 5 at 37 °C. The percentage of loading and release profiles of the drug were evaluated. The results show that the use of the matrix increased the drug release efficiency from 44.5% to 66% at pH 7.4 and 78% to 98.92% at pH 5. These results suggest that the synthesized hydroxyapatite can be used as a pH responsive vehicle for delivering drugs. Further, the release profile was predicted by the Higuchi and Peppas models. The results suggest that the release mechanism is governed by Fickian diffusion for the initial 8 h followed by anomalous transport for longer times. The cytocompatibility of the materials was evaluated by in vitro cytotoxicity tests. Both MTT and live/dead assay observations indicated that the material had no adverse impact on cell proliferation. The results imply that these composites are bioactive with good cytocompatibility. Although all the matrices showed good results, the one with polyvinyl alcohol exhibited higher biocompatibility and drug release efficiency. A plausible explanation is proposed for the enhanced drug delivery efficiency of these materials.