Green Synthesis of Silver Nanoparticles by Extracellular Extracts from Aspergillus japonicus PJ01

Abstract

The present study focuses on the biological synthesis, characterization, and antibacterial activities of silver nanoparticles (AgNPs) using extracellular extracts of Aspergillus japonicus PJ01.The optimal conditions of the synthesis process were: 10 mL of extracellular extracts, 1 mL of AgNO3 (0.8 mol/L), 4 mL of NaOH solution (1.5 mol/L), 30 °C, and a reaction time of 1 min. The characterizations of AgNPs were tested by UV-visible spectrophotometry, zeta potential, scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and thermogravimetric (TG) analyses. Fourier transform infrared spectroscopy (FTIR) analysis showed that Ag+ was reduced by the extracellular extracts, which consisted chiefly of soluble proteins and reducing sugars. In this work, AgNO3 concentration played an important role in the physicochemical properties and antibacterial properties of AgNPs. Under the AgNO3 concentration of 0.2 and 0.8 mol/L, the diameters of AgNPs were 3.8 ± 1.1 and 9.1 ± 2.9 nm, respectively. In addition, smaller-sized AgNPs showed higher antimicrobial properties, and the minimum inhibitory concentration (MIC) values against both E. coli and S. aureus were 0.32 mg/mL.

[Retracted] Fungal‐ and Algal‐Derived Synthesis of Various Nanoparticles and Their Applications

“…In addition, smaller AgNPs had better antibacterial activities against E. coli and S. aureus . Nanoparticles smaller than 10 nm have been proven under several investigations to reach the inside of bacterial cells, increasing their bactericidal activity [ 61 ]. Finally, antibiotic ampicillin and econazole nitrate demonstrated greater antibacterial activity against bacteria and mold, respectively, when compared to AgNPs.…”

Antibacterial, Antifungal, and Antioxidant Activities of Silver Nanoparticles Biosynthesized from Bauhinia tomentosa Linn

“…The antibacterial activity of biosynthesized B. tomentosa Linn flower-powder extract-derived AgNPs was investigated against Gram-negative ( E. coli ) and Gram-positive ( S. aureus ) bacterial pathogens using agar disk diffusion [ 28 , 56 , 61 , 65 , 66 ]. Briefly, a nutrient agar medium was prepared in a Petri dish and the bacterial cultures were swabbed on test media with a sterile cotton swab.…”

“…flower powder extract, (iii) AgNO 3 solution, and (iv) standard antifungal solution (fluconazole, 30 µg/mL). Each was allowed to dry before being placed on a PDA medium carrying the fungal strains and then incubated for 48 h. The diameter of the zones was measured in centimeters with the help of a scale, and the results were tabulated [ 28 , 58 , 68 , 69 ].…”

“…X-ray powder diffraction (XRD) was applied for phase identification of the Cu Kα radiation (1.5405 Å) of the AgNPs (Philips PANanalytical X'Pert XRD System (model # 3040), Amsterdam, The Netherlands) [57,64]. The antibacterial activity of biosynthesized B. tomentosa Linn flower-powder extractderived AgNPs was investigated against Gram-negative (E. coli) and Gram-positive (S. aureus) bacterial pathogens using agar disk diffusion [28,56,61,65,66]. Briefly, a nutrient agar medium was prepared in a Petri dish and the bacterial cultures were swabbed on test media with a sterile cotton swab.…”

“…Biological synthetic pathways based on microorganisms or plant extracts have been widely explored for the production of AgNPs in several applications as they are environmentally friendly and often inexpensive. Moreover, plant-based extract-mediated AgNPs synthesis is more advantageous than other biological processes because it does not require stringent aseptic environments and strict monitoring of cell culture conditions [ 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 ]. The genus Bauhinia is a member of the Leguminosae family (subfamily Caesalpiniaceae) and consists of about 300 species.…”