Biosynthesis of Silver Nanoparticles by Aspergillus terreus: Characterization, Optimization, and Biological Activities

Abstract

In this study, mycelial filtrate of Aspergillus terreus BA6 was used to reduce AgNO3 to form silver nanoparticles (AgNPs). The effect of seven independent variables on the diameter of AgNPs was studied by applying design of experiments (DOE). At optimal conditions, the diameter of AgNPs was reduced by approximately 26.7% compared to the basal culture condition and AgNO3 concentration was found to be the most significant factor affecting the diameter of AgNPs. A. terreus nano-Ag was characterized using UV-visible spectroscopy, transmission electron microscopy, energy dispersive X-ray (EDX), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Zeta potential. The maximum UV absorption was obtained at 420 nm and the microscopic results showed particles with narrow size distribution ranging from 7 to 23 nm. XRD pattern of AgNPs revealed four diffraction peaks of metallic silver and the EDX spectrum showed a strong signal attributed to Ag nano-crystals. AgNPs mycofabricated by A. terreus showed potent minimum inhibitory concentration (MIC) and broad minimum bactericidal/fungicidal concentration (MBC/MFC) against 12 reference microorganisms. The MIC and MBC/MFC values of AgNPs were 0.312 to 1.25 μg/ml and 0.625 to 10 μg/ml, respectively. Nevertheless, AgNPs did not demonstrate any antagonistic activity against Coxsackie B virus. The in vitro cytotoxicity of the mycosynthesized AgNPs showed significant antitumor activity against adenocarcinoma epithelial cells from human breast cancer (Mcf-7) cell line with an inhibitory concentration (IC50) of 87.5 μg/ml.

Soil Fungi as Biomediator in Silver Nanoparticles Formation and Antimicrobial Efficacy

“…106 The noted activity of all fungal-based NPs against K. pneumoniae might be due to the structure of cell wall of Gram-negative bacteria. 107 Regarding MIC and MBC, a recent study by Lotfy et al 94 reported a similar kind of observations when they studied NPs mediated by Aspergillus terreus against twelve bacteria, where P. aeruginosa and S. faecalis showed the highest susceptibility. Similar research by Sathiyaraj et al 92 revealed that AgNPs prepared by Vallarai chooranam showed a high zone of inhibition against E. coli and low one against Bacillus subtilis.…”

“… 87 The peaks at 3.0 keV in the EDX spectrum represented Ag attributed to the SPR of Ag nanocrystals as reported earlier. 92 , 94 …”

“…87 The peaks at 3.0 keV in the EDX spectrum represented Ag attributed to the SPR of Ag nanocrystals as reported earlier. 92,94 Results obtained from DLS analysis revealed a wide base of recorded peaks referring to variable sizes of the formed AgNPs. 93 The higher size detected for fungal-based NPs by DLS compared to the primary size measured by TEM displayed some sort of particle aggregation in the water solution which related to the frequency of NPs collisions as interparticular interactions increase.…”

Green synthesized silver nanoparticles using Cyperus rotundus L. extract as a potential antiviral agent against infectious laryngotracheitis and infectious bronchitis viruses in chickens

“…The cytotoxicity of aqueous extract and green synthesized SNPs were tested on the Vero cells by MNTC method of each extract that determined in the range of the cytotoxic concentrations at 0-600 µg mL −1 for aqueous extract, and 0-200 µg mL −1 for SNPs pre-and postinfection treatment using 10 4.8 and 10 3.7 TCID 50 mL −1 for IBV and ILTV viruses, respectively. Microscopically demonstrated normal cell morphology was observed and no cytotoxic effect of the extracts on the Vero cells in the range of the cytotoxic concentrations at 0-400 µg mL −1 of aqueous extract, and 0-50 µg mL −1 for SNPs (Table 2) [45,46].…”

Superior in vivo Wound-Healing Activity of Mycosynthesized Silver Nanogel on Different Wound Models in Rat

“…Silver nitrate is a well-known antimicrobial agent used in the treatment of chronic wounds and for many other medical purposes since ancient times (Paladini and Pollini, 2019 ; Talapko et al, 2020 ; Chinnasamy et al, 2021 ). Silver NPs (AgNPs) show a potent activity against a broad range of Gram-negative and Gram-positive, aerobic and anaerobic bacteria, filamentous fungi, yeast, and viruses (Gaikwad et al, 2013a ; Dakal et al, 2016 ; Alavi and Rai, 2021 ; Lotfy et al, 2021 ; Zawadzka et al, 2021 ; Alavi et al, 2022 ). In the beginning of the twentieth century, morbidity, and mortality were major consequences of burn wound infections (Norbury et al, 2016 ; Ladhani et al, 2021 ).…”