Biogenic Ag/CaO nanocomposites kill Staphylococcus aureus with reduced toxicity towards mammalian cells.

Rapid increase in the case of bacterial infections is considered as a major public health concern and hence exploration of alternative treatment procedures including development of nanomaterials based therapeutic strategies is receiving much attention. In this aspect, here we investigated the antibacterial efficacy of a simple and potential metal/metal oxide nanocomposite system. Biogenic synthetic protocol was designed for processing of Ag/CaO nanocomposites (NCs). Structural features and morphology of the synthesized nanomaterials were investigated by X-ray diffraction (XRD) and electron microscopy techniques respectively. Optical properties of the nanomaterials were analyzed by UV-vis spectrophotometer. Presence of water and possible impurity molecules on the materials surface was examined by Fourier-transform infrared spectroscopy (FTIR). Effective antibacterial activity of the NCs was observed (within a range of 25-150 μg/mL of NCs) against Staphylococcus aureus (S. aureus) and Methicillin-resistant Staphylococcus aureus (MRSA). The potential anti-biofilm effect of as synthesized NCs was tested against S. aureus. Experimental results suggest that the antibacterial action of the NCs could be due to the induction of reactive oxygen species (ROS). DNA degradation and change in the bacterial cell membrane has further indicated the complete disinfection of the target bacterial system. The cytotoxicity evaluation has confirmed that the formation of NCs has maintained the antibacterial efficacy of Ag NPs but reduced its toxicity towards mammalian cells.