Autoclave-assisted green synthesis of silver nanoparticles using A. fumigatus mycelia extract and the evaluation of their physico-chemical properties and antibacterial activity

Abstract

Silver nanoparticles (AgNPs) were synthesized using Aspergillus fumigatus (A. fumigatus) mycelia extract via the hydrothermal method. The main reducing and stabilizing groups and components of A. fumigatus extract, such as amine, hydroxyl, amid, protein, enzymes, and cell saccharide compounds, were identified by Fourier transform infrared (FT-IR). Central composition design was used to plan the experiments, and response surface methodology was applied to evaluate of the effects of independent variables, including the amount of the prepared extract (5-7 ml) and heating time (10-20 min) at 121 degrees C and 1.5 bar), on the particle size of the synthesized AgNPs, as manifested in broad emission peak (lambda(max)). More stable and spherical monodispersed AgNPs, with mean particle size, polydispersity index (PDI) value, and maximum zeta potential value of 23 nm, 0.270, and +35.3 mV, respectively, were obtained at the optimal synthesis conditions using 7 ml of A. fumigatus extract and heating time of 20 min. The synthesized AgNPs indicated high antibacterial activity against both Gram-positive and Gram-negative bacteria.