Green Strategy–Based Synthesis of Silver Nanoparticles for Antibacterial Applications

Abstract

Antibiotics have been the nucleus of chemotherapy since their discovery and introduction into the healthcare system in the 1940s. They are routinely used to treat bacterial infections and to prevent infections in patients with compromised immune systems and enhancing growth in livestock. However, resistance to last-resort antibiotics used in the treatment of multidrug-resistant infections has been reported worldwide. Therefore, this study aimed to evaluate green synthesized nanomaterials such as silver nanoparticles (AgNPs) as alternatives to antibiotics. UV-vis spectroscopy surface plasmon resonance peaks for AgNPs were obtained between 417 and 475 nm. An X-ray diffraction analysis generated four peaks for both Prunus africana extract (PAE) and Camellia sinensis extract (CSE) biosynthesized AgNPs positioned at 2θ angles of 38.2°, 44.4°, 64.5°, and 77.4° corresponding to crystal planes (111), (200), (220), and (311), respectively. A dynamic light-scattering analysis registered the mean zeta potential of +6.3 mV and +0.9 mV for PAE and CSE biosynthesized nanoparticles, respectively. Fourier transform infrared spectroscopy spectra exhibited bands corresponding to different organic functional groups confirming the capping of AgNPs by PAE and CSE phytochemicals. Field emission scanning electron microscopy imaging showed that AgNPs were spherical with average size distribution ranging from 10 to 19 nm. Biosynthesized AgNPs exhibited maximum growth inhibitory zones of 21 mm with minimum inhibitory concentration and minimum bactericidal concentration of 125 and 250 μg/ml, respectively, against carbapenem-resistant bacteria.

Strong Antimicrobial Activity of Silver Nanoparticles Obtained by the Green Synthesis in Viridibacillus sp. Extracts

“…The authors showed the MBC value of AgNPs against E. coli and P. aeruginosa were 110 and 105 µg/mL (Devanesan and AlSalhi, 2021). Loo et al (2018) described the MBC value of extremely small 4 nm AgNPs produced using pu-erh tea leaves Ssekatawa et al, 2021). Thus, our G-AgNPs showed MBC at 8 and 1 µg/mL against E. coli and P. aeruginosa, superior to all the cited examples.…”

“…One such popular approach is using bacteria as a cell factory to produce the AgNPs extracellularly. In addition, to producing biocompatible NPs, bacteria-mediated synthesis is low-cost, environmentally friendly, safe, and simple ( Xu et al, 2020 ; Ssekatawa et al, 2021 ).…”

“…( Figure 1 ). Recently Ssekatawa et al (2021) showed the green synthesis of AgNPs from the extract of medicinal plants– Camellia sinensis and Prunus Africana . The current study deals with the extracellular synthesis of G-AgNPs from an environmental isolate without any additives for the reduction or stabilization process.…”

Green Synthesis and Potential Antibacterial Applications of Bioactive Silver Nanoparticles: A Review

“…This result revealed that the synthesized AgNPs showed strong inhibitory activity against tested pathogens [44]. Plantago major, Prunus africana and Camellia sinensis were also reported to synthesize small-size AgNPs and evaluated against S. aureus, E. coli, P. aeruginosa and K. pneumoniae [25,35]. It has been reported that smaller size NPs showed higher antibacterial activities due to the larger surface area [146].…”

“…According to Adeyemi et al [34], the leaf extract of Spondias mombin produced rod-or triangular-shaped AgNPs. However, the plant extract of Prunus africana, and Camellia sinensis produced spherical-shaped AgNPs [35]. Various parameters such as the extract salt ratio, incubation time, incubation temperature, pH, etc.…”