Enhanced Biosynthesis of Coated Silver Nanoparticles using Isolated Bacteria from Heavy Metal Soils and their Photothermal- based antibacterial activity: Integrating Response Surface Methodology (RSM) Hybrid Artificial Neural Network (ANN)- Genetic Algorithm (GA) Strategies

Abstract

This study explores the biosynthesis of silver nanoparticles (AgNPs) using the Streptomyces tuirus S16 strain, presenting an eco-friendly alternative to mitigate the environmental and health risks of chemical synthesis methods. It focuses on optimizing medium culture conditions, understanding their physicochemical properties, and investigating their potential photothermal-based antibacterial application. The S16 strain was selected from soil heavy metals to exploit its ability to produce diverse bioactive compounds. By employing the combination of Response Surface Methodology (RSM) and Artificial Neural Network (ANN)-Genetic Algorithm (GA) strategies, we optimized AgNPs synthesis, achieving a significant 59.2% improvement in yield under specific conditions (Bennet's medium supplemented with glycerol [5g/L] and casamino-acid [3g/L] at 30°C for 72h). A detailed physicochemical characterization was conducted. Notably, the AgNPs were well dispersed, and a carbonaceous coating layer on their surface was confirmed using Energy-Dispersive X-ray Spectroscopy. Furthermore, functional groups were identified using Fourier-transform infrared spectroscopy, which helped enhance the AgNPs' stability and biocompatibility. AgNPs also demonstrated efficient photothermal conversion under light irradiation (0,2w/cm²), with temperatures increasing to 41.7°C, after 30minutes. In addition, treatment with light irradiations against E.coli K-12 model effectively reduced the concentration of AgNPs from 105 to 52.5µg/mL, thereby to enhancing the efficacy of silver nanoparticles in contact with the E. coli K-12 model