Generation of a Hydroxyapatite Nanocarrier through Biomineralization Using Cell-Free Extract of Lactic Acid Bacteria for Antibiofilm Application.

Nanoscale materials hold considerable promise in the mitigation of bacterial infections. In order to exploit nanomaterials as delivery systems in an antibacterial therapeutic paradigm, it is critical to ensure that the generated material is nontoxic. Based on the fundamental principle of biomineralization, we herein report the generation of biocompatible hydroxyapatite nanoparticles (HANPs) in the presence of proteins secreted by the lactic acid bacteria (LAB) MTCC 1325, CRA52, and CRA51. The biogenic HANPs were characterized by AFM, FETEM, powder XRD, DLS, and FTIR analysis. Interestingly, HANPs could also be synthesized using an ∼20 kDa protein purified from the secreted protein extract obtained from MTCC 1325, which suggested that this lower molecular weight protein fraction was perhaps significantly involved in biomineralization-based generation of HANPs. In order to develop a therapeutic bactericidal nanocomposite, HANPs were loaded with the antibiotic polymyxin B (PB). A Langmuir isotherm model was evident in the studies that measured adsorption of PB onto HANPs. A sustained release profile of PB from the nanocomposite was observed in buffers having varying pH and in simulated body fluid. The nanocomposite (PB-HNC) exhibited bactericidal as well as antibiofilm activity against MTCC 2488 and was nontoxic to cultured human embryonic kidney cells.