Molecular Weight Identification of Compounds Involved in the Fungal Synthesis of AgNPs: Effect on Antimicrobial and Photocatalytic Activity

Abstract

The biological synthesis of silver nanoparticles (AgNPs) for medical, environmental, and industrial applications is considered an alternative to chemical synthesis methods. Additionally, the reducing, capping, and stabilizing molecules produced by the organisms can play a key role in the further activity of AgNPs. In this work, we evaluated the synthesis of AgNPs by four molecular weight fractions (S1: <10 kDa, S2: 10 to 30 kDa, S3: 30 to 50 kDa, and S4: >50 kDa) of mycelia-free aqueous extract produced by the white-rot fungus Stereum hirsutum and their effect on the antimicrobial activity against Pseudomonas syringae and photocatalytic decolorization of nine synthetic dyes exposed to sunlight radiation. All synthesis assay fractions showed the characteristic surface plasmon resonance (SPR) with 403 to 421 nm peaks. TEM analysis of synthesized AgNPs showed different sizes: the whole mycelia-free extracts S0 (13.8 nm), S1 (9.06 nm), S2 (10.47 nm), S3 (22.48 nm), and S4 (16.92 nm) fractions. The results of disk diffusion assays showed an inverse relation between antimicrobial activity and the molecular weight of compounds present in the mycelia-free aqueous extract used to synthesize AgNPs. The AgNPs synthesized by S0 (14.3 mm) and S1(14.2 mm) generated the highest inhibition diameter of P. syringae growth. By contrast, in the photocatalytic assays, the AgNPs synthesized by the S2 fraction showed the highest discoloration in all the dyes tested, reaching 100% of the discoloration of basic dyes after 2 h of sunlight exposure. The maximum discoloration observed in reactive and acid dyes was 53.2% and 65.3%, respectively. This differentiation in the antimicrobial and photocatalytic activity of AgNPs could be attributed to the capping effect of the molecules present in the extract fractions. Therefore, the molecular separation of synthesis extract enables the specific activities of the AgNPs to be enhanced.

The Antifungal Activities of Silver Nano-Aggregates Biosynthesized from the Aqueous Extract and the Alkaline Aqueous Fraction of Rhazya stricta against Some Fusarium Species

“…Furthermore, certain fungi can create and release mycotoxins, which are toxic to humans and animals. To prevent such illnesses, chemical fungicides and pesticides have been utilized; nevertheless, these treatments have had a significant influence on the environment and, as a result, human health [ 45 ]. Plant extracts and plant-based AgNPs were used in this work to assess their effectiveness against four phytopathogenic Fusarium species.…”

“…In agreement with our findings, a previous study showed that the Aq-extract of R. stricta affected the mycelial growth of F. solani with a zone of inhibition (ZOI) of 16 ± 0.3 mm, where the biosynthesized AgNPs induced a ZOI of 26 ± 0.5 mm [ 36 ]. Another study showed that the methanolic extract of R. stricta affected the mycelial growth of F. solani with a ZOI of 18 mm [ 45 , 46 ].…”

Network pharmacology combined with an experimental validation study to reveal the effect and mechanism of Lonicera japonica Thunb. extracts against immunomodulation

“…The total polyphenol contents (TPC) of LJTE were determined as previously described (Vera et al, 2023). A standard curve of gallic acid (Titan Scientific) was plotted as the standard (Y = 0.01166X + 0.08603, R 2 = 0.997).…”

Innovating Leishmaniasis Treatment: A Critical Chemist’s Review of Inorganic Nanomaterials

“…The surfaces of metallic nanoparticles are easily functionalized, allowing the attachment of various molecules, such as antibodies and probes . The therapeutic applications of metallic nanoparticles have demonstrated potential in antimicrobial, − anticancer, − and antileishmanial activities, targeting both promastigotes and amastigotes forms of Leishmania protozoans. − Their mechanism of action is primarily associated with the increased concentration of reactive oxygen species (ROS). , Within the mammalian body, the nanoparticles are recognized as pathogens and engulfed by macrophages, which maintain an acidic environment (pH ∼ 5.8) conducive to metal oxidation . The high surface-volume ratio of metallic nanoparticles facilitates a rapid rate of surface oxidation .…”