Highly stable reinforced nanostructure of silver-decorated on graphene oxide phytosynthesized through central composite design for antibacterial activity: Green and eco-friendly method

Abstract

In this study, the simultaneous effects of reaction time, reaction temperature, and ratio of AgNO3 and Curcuma longa extract on the nanoparticle size in the silver nanoparticles@graphene oxide (Ag@GO) nanocomposite were thoroughly investigated via the central composite design model (CCD). The obtained results showed that all parameters played a crucial role in the change in the AgNPs size. Indeed, the synthesis conditions were determined to be 31.9 min, 60.22 °C, and volume ratio between AgNO3 and extract of 0.96 (mL/mL) according to the simulated model, while these were determined at 32 min, 60 °C, and 1.0 (mL/mL) of AgNO3:extract volume ratio in empirical experiments. Under these conditions, the average particle size of the AgNPs was determined to be 22.19 nm, which showed a negligible deviation as compared to the experimental result (23.47 nm). Furthermore, the characterization of the Ag@GO was also assessed, in which the AgNPs affirmed the presence of spherical shapes evenly distributed on the GO sheets through XPS spectra, XRD pattern, TEM, and AFM images results. In addition, the as-prepared material also shows a great antibacterial performance against both Escherichia coli and Staphylococcus aureus strains with the IC50 values of 2.70 and 2.86 μg/mL at the bacteria density of 108 CFU/mL. Besides, the stability of the Ag@GO material in the form of suspension after 3 months was also evaluated, in which insignificant changes in the morphological structure were observed as compared to the initial sample. The aforementioned results exerted the great potential of the as-prepared material as an antibacterial agent in medicinal applications.