Silver-Protein Nanocomposites as Antimicrobial Agents

Mahmoud Sitohy; Abdul-Raouf Al-Mohammadi; Ali Osman; Seham Abdel-Shafi; Nashwa El-Gazzar; Sara Hamdi; Sameh H Ismail; Gamal Enan

doi:10.3390/nano11113006

Silver-Protein Nanocomposites as Antimicrobial Agents

Nanomaterials (Basel). 2021 Nov 9;11(11):3006. doi: 10.3390/nano11113006.

Authors

Mahmoud Sitohy¹, Abdul-Raouf Al-Mohammadi², Ali Osman¹, Seham Abdel-Shafi³, Nashwa El-Gazzar³, Sara Hamdi³, Sameh H Ismail⁴, Gamal Enan³

Affiliations

¹ Biochemistry Department, Faculty of Agriculture, Zagazig University, Zagazig 44511, Egypt.
² Department of Science, King Khalid Military Academy, P.O. Box 22140, Riyadh 11495, Saudi Arabia.
³ Botany and Microbiology Department, Faculty of Science, Zagazig University, Zagazig 44519, Egypt.
⁴ Faculty of Nanotechnology for Postgraduate, Cairo University, Zayed City 12588, Egypt.

Abstract

The use of nanomaterials alone or in composites with proteins is a promising alternative to inhibit pathogenic bacteria. In this regard, this study used seed proteins from both fenugreek (Trigonella foenum-graecum L.) (FNP) and mung bean (Viga radiate) (MNP), with silver nanoparticles (Ag-NPs) and nanocomposites of either Ag-NPs plus FNP (Ag-FNP) or Ag-NPs plus MNP (Ag-MNP) as inhibitory agents against pathogenic bacteria. FNP and MNP were isolated from fenugreek seeds and mung bean seeds, respectively, and fractionated using Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis (SDS-PAGE). Both FNP and MNP were immobilized with Ag-NPs to synthesize the nanocomposites Ag-FNP and Ag-MNP, respectively. The physicochemical characteristics of Ag-NPs and their composites with proteins were studied by X-ray Diffraction (XRD), dynamic light scattering (DLS), the zeta potential, Scanning and Transmission Electron Microscopy (SEM and TEM, respectively), Atomic Force Microscopy (AFM), and the Brunauer-Emmett-Teller isotherm (BET), elucidating their structural parameters, size distribution, size charges, size surface morphology, particle shape, dimensional forms of particles, and specific surface area, respectively. The sole proteins, Ag-NPs, and their nanocomposites inhibited pathogenic Gram-positive and Gram-negative bacteria. The inhibitory activities of both nanocomposites (Ag-FNP and Ag-MNP) were more than those obtained by either Ag-NPs or proteins (FNP, MNP). Minimum inhibitory concentrations (MICs) of Ag-FNP were very low (20 and 10 µg mL^-1) against Salmonellatyphimurium and Pseudomonasaerugenosa, respectively, but higher (162 µg mL^-1) against E. coli and Listeriamonocytogenes. MICs of Ag-MNP were also very low (20 µg mL^-1) against Staphylococcusaureus but higher (325 µg mL^-1) against Listeriamonocytogenes. TEM images of Staphylococcusaureus and Salmonellatyphimurium, treated with Ag-FNP and Ag-MNP, at their MIC values, showed asymmetric, wrinkled exterior surfaces, cell deformations, cell depressions, and diminished cell numbers.

Keywords: antibacterial activity; fenugreek; mung bean; nanocomposite; seed proteins; silver nanoparticles.