Biological Synthesis of Monodisperse Uniform-Size Silver Nanoparticles (AgNPs) by Fungal Cell-Free Extracts at Elevated Temperature and pH

Abstract

Fungi’s ability to convert organic materials into bioactive products offers environmentally friendly solutions for diverse industries. In the nanotechnology field, fungi metabolites have been explored for green nanoparticle synthesis. Silver nanoparticle (AgNP) research has grown rapidly over recent years mainly due to the enhanced optical, antimicrobial and anticancer properties of AgNPs, which make them extremely useful in the biomedicine and biotechnology field. However, the biological synthesis mechanism is still not fully established. Therefore, this study aimed to evaluate the combined effect of time, temperature and pH variation in AgNP synthesis using three different fungi phyla (Ascomycota, Basidiomycota and Zygomycota) represented by six different fungi species: Cladophialophora bantiana (C. bantiana), Penicillium antarcticum (P. antarcticum), Trametes versicolor (T. versicolor), Trichoderma martiale (T. martiale), Umbelopsis isabellina (U. isabellina) and Bjerkandera adusta (B. adusta). Ultraviolet–visible (UV-Vis) spectrophotometry and transmission electron microscopy (TEM) results demonstrated the synthesis of AgNPs of different sizes (3 to 17 nm) and dispersity percentages (25 to 95%, within the same size range) using fungi extracts by changing physicochemical reaction parameters. It was observed that higher temperatures (90 °C) associated with basic pH (9 and 12) favoured the synthesis of monodisperse small AgNPs. Previous studies demonstrated enhanced antibacterial and anticancer properties correlated with smaller nanoparticle sizes. Therefore, the biologically synthesised AgNPs shown in this study have potential as sustainable substitutes for chemically made antibacterial and anticancer products. It was also shown that not all fungi species (B. adusta) secrete metabolites capable of reducing silver nitrate (AgNO3) precursors into AgNPs, demonstrating the importance of fungal screening studies.

Green Extracellular Synthesis of Silver Nanoparticles by Pseudomonas alloputida, Their Growth and Biofilm-Formation Inhibitory Activities and Synergic Behavior with Three Classical Antibiotics

“…Since the XRD analyses, which will be described later, have shown that AgNPs synthesized in the presence of NaCl contain AgCl crystals, we can guess that these were nucleating the AgNPs. In the literature, a wide range of synthesis rates for silver nanoparticles has been reported depending on the biological material used or the synthesis method and conditions, such as pH [ 50 ], temperature [ 29 , 50 ], or NaCl presence [ 29 , 49 ]. In previous work by our group [ 29 ], the presence of NaCl did not speed up AgNP synthesis; the contrary was true.…”

Biological Synthesis of Low Cytotoxicity Silver Nanoparticles (AgNPs) by the Fungus Chaetomium thermophilum—Sustainable Nanotechnology

“…The AgNP synthesis activity level of the C. thermophilum cell-free extract was tested following the study by Alves and Murray [ 3 ]. Briefly, the cell-free extract was heated for 15 min at 90 °C; then, 127.40 mg/L silver nitrate (AgNO 3 , Sigma-Aldrich, St. Louis, MO, USA) was added for a total volume of 500 μL, and heating was continued for one hour at 90 °C.…”

“…The resulting AgNPs were characterised based following the study by Alves and Murray [ 3 ]. Ultraviolet–visible spectrophotometry (UV-Vis, BioTek Synergy 4 Microplate Reader, Bad Friedrichshall, Germany) was first used to measure the localised surface plasmon resonance (LSPR) absorbance.…”

“…Over-exploitation of natural resources and exponential human growth are the roots of modern social concerns [ 1 ]. In this context, sustainable consumption and production patterns, extensively described by the United Nations in the Sustainable Development Agenda as Goal 12, have inevitably become needed [ 2 ]; hence, the growing attention given to sustainable development and the pressing need to explore sustainable options [ 3 ]. As a result, physical and chemical processes are gradually being replaced by biological ones.…”

Insights into the recent advances in nano-bioremediation of pesticides from the contaminated soil

“…Studies have reported that metals like gold, silver, titanium, platinum, selenium, palladium and silica can be utilized for the fabrication of nanoparticles ( Gholami-Shabani et al, 2016 ). Silver nanoparticles (AgNPs) synthesized from F. oxysporum are different in features from those synthesized with Aspergillus fumigates ( Alves and Murray, 2022 ). Studies have reported the synthesis of AgNPs using Coriolus versicolor and Trichoderma reesei ( Vahabi et al, 2011 ; Deniz et al, 2019 ).…”