Synthesis and Characterization of Silver and Graphene Nanocomposites and Their Antimicrobial and Photocatalytic Potentials

Abstract

Microbial pathogens and bulk amounts of industrial toxic wastes in water are an alarming situation to humans and a continuous threat to aquatic life. In this study, multifunctional silver and graphene nanocomposites (Ag)1−x(GNPs)x [25% (x = 0.25), 50% (x = 0.50) and 75% (x = 0.75) of GNPs] were synthesized via ex situ approach. Further, the synthesized nanocomposites were explored for their physicochemical characteristics, such as vibrational modes (Raman spectroscopic analysis), optical properties (UV visible spectroscopic analysis), antibacterial and photocatalytic applications. We investigated the antimicrobial activity of silver and graphene nanocomposites (Ag-GNPs), and the results showed that Ag-GNPs nanocomposites exhibit remarkably improved antimicrobial activity (28.78% (E. coli), 31.34% (S. aureus) and 30.31% (P. aeruginosa) growth inhibition, which might be due to increase in surface area of silver nanoparticles (AgNPs)). Furthermore, we investigated the photocatalytic activity of silver (AgNPs) and graphene (GNPs) nanocomposites in varying ratios. Interestingly, the Ag-GNPs nanocomposites show improved photocatalytic activity (78.55% degradation) as compared to AgNPs (54.35%), which can be an effective candidate for removing the toxicity of dyes. Hence, it is emphatically concluded that Ag-GNPs hold very active behavior towards the decolorization of dyes and could be a potential candidate for the treatment of wastewater and possible pathogenic control over microbes. In the future, we also recommend different other in vitro biological and environmental applications of silver and graphene nanocomposites.

Three-Dimensional Reduced Graphene Oxide Hybrid Nano-Silver Scaffolds with High Antibacterial Properties

“…As schematically illustrated in Figure 1 and Supplementary Materials Figure S2 , a 3D reduced graphene oxide (3D rGO) scaffold was synthesized through a modified hydrothermal process followed by a freeze-drying process [ 29 ]. To obtain 3D reduced graphene oxide (rGOA), the first step was to use a modified Hummer’s process to synthesize graphene oxide (GO) [ 27 ].…”

“…However, previous research showed AgNPs alone showed less inhibition in all three bacterial strains as compared to Ag-GNPs nanocomposites. Among all Ag-GNPs nanocomposites, 50% GNPs-Ag are more towards inhibiting pathogens, i.e., 28.78% ( E. coli ), 31.34% ( S. aureus ) and 30.31% ( P. aeruginosa ) as compared to AgNPs, i.e., 19.78% ( E. coli ), 17.91% ( S. aureus ) and 20.97% ( P. aeruginosa ), respectively [ 29 ]. Additionally, these scattered nanocomposites did not exist as three-dimensional entities, so it was difficult to collect the Ag–GO nanocomposite from water after antibacterial processes, which was not conducive to the reuse of antibacterial agent as well as the environmental protection.…”

Recent Advances in the Development of Lipid-, Metal-, Carbon-, and Polymer-Based Nanomaterials for Antibacterial Applications

“…As mentioned in Section 3 , the shortcomings of metal nanoparticles limit their potential for medical applications. To overcome these issues, many nanocomposites composed of metal nanoparticles and graphene have been prepared experimentally and studied against various bacterial strains [ 287 , 288 , 289 , 290 , 291 , 292 ]. Some of the available literature reviewed the development of graphene–metal matrix nanocomposites which will not be repeated here [ 293 , 294 , 295 , 296 ].…”

“…The enhanced antibacterial activity of GO–Ag nanocomposites is often ascribed to the synergistic activity of GO and Ag; however, the full antibacterial mechanism remains to be elucidated [ 299 ]. Malik et al have also demonstrated that GO–Ag nanocomposites exhibit significantly enhanced growth inhibition of E. coli , S. aureus , and P. aeruginosa relative to silver nanoparticles alone [ 291 ]. Recent studies have accomplished the surface functionalization of GO and Ag nanoparticles by using lantana plant extract, and the results also affirmed the potential of GO–Ag nanocomposites as antibacterial agents against biological pollutants [ 290 ].…”

“…Upon encountering bacteria that secrete hyaluronidase, such as S. aureus , hyaluronic acid is degraded, followed by interaction of the GO–Ag nanocomposite and bacteria to further enhance the antibacterial action. Together with the photocatalytic characteristic of GO, local photothermal therapy under light irradiation could be achieved to further enhance the antibacterial activity of the GO–Ag nanocomposite [ 291 ].…”