Green synthesis of bioactive graphene oxide-silver nanocomposites optimized by the response surface methodology

The graphene oxide-silver nanocomposites (AgNPs@GO) have attracted much attention due to their targeted effect and nontoxicity against normal cells. The toxic factors, including the chemical reagents during the synthesis of AgNPs@GO, must be considered and minimized for the cancer treatment application. This study aims to apply the response surface methodology (RSM) with central composite design (CCD) for investigating independent factors, including mass ratio Ag+/GO, temperature, and reaction time, to find the optimal conditions for graphene oxide-silver nanocomposite (AgNPs@GO) synthesis. The green tea leaves extract was used as an alternative reducing agent for the green synthesis of AgNPs@GO. The maximum absorption wavelength of AgNPs, highly dependent on silver nanoparticles' size and shape, was utilized as the target function. The results show optimal conditions for the green synthesis of AgNPs@GO with the mass ratio of Ag+/GO is 2:1 at 30 °C for 40 minutes. The average maximum absorption wavelength of the synthesized AgNPs@GO at the optimal condition of 416.78 nm, with silver nanoparticles on the GO sheet having an average size of 21.2 ± 5.61 nm, the round shape and distributed on the GO sheets uniformly, without aggregation. In addition, the synthesized AgNPs@GO was against HepG2, MDA231, and MDA453, with the IC₅₀ of 152.582, 152.428, and 199.844 μg/mL, respectively.