Synthesis of Silver Nanoparticles Mediated by Fungi: A Review

Abstract

The use of fungi as reducing and stabilizing agents in the biogenic synthesis of silver nanoparticles is attractive due to the production of large quantities of proteins, high yields, easy handling, and low toxicity of the residues. Furthermore, this synthesis process coats the nanoparticles with biomolecules derived from the fungus, which can improve stability and may confer biological activity. The aim of this review is to describe studies in which silver nanoparticles were synthesized using fungi as reducing agents, discussing the mechanisms and optimization of the synthesis, as well as the applications. The literature shows that various species of fungus have potential for use in biogenic synthesis, enabling the production of nanoparticles with different characteristics, considering aspects such as their size, surface charge, and morphology. The synthesis mechanisms have not yet been fully elucidated, although it is believed that fungal biomolecules are mainly responsible for the process. The synthesis can be optimized by adjusting parameters such as temperature, pH, silver precursor concentration, biomass amount, and fungus cultivation time. Silver nanoparticles synthesized using fungi enable the control of pathogens, with low toxicity and good biocompatibility. These findings open perspectives for future investigations concerning the use of these nanoparticles as antimicrobials in the areas of health and agriculture.

Biogenic Metal Nanoparticles: A New Approach to Detect Life on Mars?

“…The popularity of silver NPs (AgNPs) is due to their localized surface Plasmon resonance, good conductivity, chemical stability, catalytic and broad-spectrum anti-microbial activities, as well as cytotoxic effect on cancer cells [11]. They have been employed mostly for their antimicrobial capacity in the medical, food packaging and textile (by incorporation in hybrid materials), and agriculture industries, but also for catalytic, anticancer and antioxidant applications, antiviral action and anti-inflammatory activity (e.g., for HIV), in cosmetics, electronics, and energy [5,7,[11][12][13]. Besides their activity against microorganisms, they also prevent microbial growth and inhibit the formation of biofilms, making them very useful as a component of many materials and tools for the food industry, biomedical applications, engineering sciences, and agriculture [7].…”

“…Chemical synthesis of MNPs implies the reduction of metal salts/ions in solution or decomposition of precursors, to form small assemblages of metal atoms, via the use of hazardous chemicals such as sodium borohydride, tetrakishydroxymethylphosphonium chloride (THPC), poly-N-vinyl pyrrolidone (PVP), and hydroxylamine [20], as well as solvents like sodium dodecyl sulfate (SDS), sodium borohydrate, hyperbranched polyester, and hydrocarbons [22], followed by aggregation of atoms [2]. Some of those chemicals are also used to stabilize the NPs [13].…”

“…The capacity for biosynthesis of MNPs has a remarkably widespread distribution (Table 2), including representatives of Bacteria, Archaea, and Eukarya and even extends to viruses [13,20,23]. In general screenings for testing production, some species and strains are classified as non-producers (e.g., [5,[24][25][26]).…”

Metal Nanoparticle–Microbe Interactions: Synthesis and Antimicrobial Effects

“…This indicates that when the AgNO 3 concentration was increased the functional groups available for the reaction were lacking. [ 216 ] Gudikandula et al reported that 15 nm size silver nanoparticles were synthesized within 12–48 h (reduction time) by using the biomass of the fungus, Ganoderma enigmaticum (3.9–5.2 g/100 mL solution) in AgNO 3 at 60 µL of 1.5 × 10 −3 m concentrations. [ 217 ] The synthesized Ag NPs caused strong antimicrobial effects against B. subtilis , S. aureus , M. luteus , B. cereus , B. megaterium , E. coli , E. aerogens , K. pneumonia , P. vulgaris , P. aeruginosa , and S. paratyphi .…”

Skirmishing MDR strain of Candida albicans by effective antifungal CeO2 nanostructures using Aspergillus terreus and Talaromyces purpurogenus

“…In the previous studies, it is reported that the proteins and reductases released in the fungal filtrates resulted in the reduction of ions to nanoparticles. Literature supporting the idea that the reduced form (NADH) and NADH dependent reductase enzyme are the possible reasons for the reduction of ions to nanoparticles [22].…”