in vitro antibacterial effect of forsterite nanopowder: synthesis and characterization

The synthesized forsterite is usually associated with various amounts of periclase (MgO), silicon dioxide (SiO2), and enstatite (MgSiO3). However, the role of different thermal treatment conditions on the optimal formation of pure forsterite and its antimicrobial activity is not yet deeply evaluated. So, the goal of this study was the preparation, characterization and in vitro antibacterial activity evaluation of forsterite nanopowder (FS, Mg2SiO4) obtained by two major methods, namely sol-gel (FSsg) and co-precipitation (FSpp). To assess the best working temperature for the preparation of FSsg and FSpp, the synthesis and thermal treatment conditions were optimized on the basis of thermal gravimetric (TG) and differential scanning calorimetric (DSC) analysis performed on the dried gel and dried co-precipitated solid, respectively. The FSsg and FSpp powders were characterized by X-ray powder diffraction (XRD) indicating a high purity for both FSs and FSpp powders. The morphology of FSsg and FSpp nanopowders was explored by scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDX) and atomic force microscopy (AFM). In vitro antibacterial activity was investigated using a targeted pathogen, namely Staphylococcus aureus ATCC 6538 P as tested strain by broth dilution technique and inoculations on nutrient agar to highlight the bactericidal inhibitory effect. FSsg nanopowder has no inhibitory capacity, while FSpp produced inhibition, the effect being bactericidal at a concentration of 10 mg/mL. The superior bactericidal activity of FSpp against FSsg is due to variation in the own surface properties, such as specific surface area and nano-regime particle size. The FSpp obtained by co-precipitation method is reported for the first time as a novel bactericidal nanomaterial against Staphylococcus aureus. The nanoparticles, NPs, of FSpp exhibited good intrinsic antibacterial activity, which might potentiate its effect as antibiotic nanocarrier against Staphylococcus aureus. Thus, the novel FSpp may serve as an efficient antibacterial nanomaterial for its biomedical applications in pharmaceutical fields.