Development of Multi-Concentration Ag:Cu Bimetallic Nanoparticles as a Promising Bactericidal for Antibiotic-Resistant Bacteria as Per Molecular Docking Exploration

Abstract

The present study is concerned with the influence of various concentrations of Ag within Cu:Ag bimetallic nanoparticles developed for use as a promising anti-bacterial agent against antibiotic-resistant bacteria. Here, Cu:Ag bimetallic nanoparticles (NPs) with various concentration ratios (2.5, 5.0, 7.5, and 10 wt.%) of Ag in fixed amount of Cu labeled as 1:0.025, 1:0.050, 1:0.075, and 1:0.1 were synthesized using co-precipitation method with ammonium hydroxide and deionized water as solvent, polyvinyl pyrrolidone as a capping agent, and sodium borohydride and ascorbic acid as reducing agents. These formulated products were characterized through a variety of techniques. XRD confirmed phase purity and detected the presence of distinct fcc structures belonging to Cu and Ag phases. FTIR spectroscopy confirmed the presence of vibrational modes corresponding to various functional groups and recorded characteristic peak emanating from the bimetallic. UV-visible spectroscopy revealed reduction in band gap with increasing Ag content. SEM and HR-TEM micrographs demonstrated spherical morphology of Ag-doped Cu bimetallic with small and large scale agglomerations. The samples exhibited varying dimensions and interlayer spacings. Bactericidal action of synthesized Cu:Ag bimetallic NPs depicted statistically significant (P < 0.05) inhibition zones recorded for various concentrations of Ag dopant against Staphylococcus aureus (S. aureus), Escherichia coli (E. coli), and Acinetobacter baumannii (A. baumannii) ranging from (0.85 – 2.8 mm), (0.55 – 1.95 mm) and (0.65 – 1.85 mm), respectively. Broadly, Cu:Ag bimetallic NPs were found to be more potent against gram-positive compared with gram-negative. Molecular docking study of Ag-Cu bimetallic NPs was performed against β-lactamase which is a key enzyme of cell wall biosynthetic pathway from both S. aureus (Binding score: -4.981 kcal/mol) and A. bauminnii (Binding score: -4.013 kcal/mol). Similarly, binding interaction analysis against FabI belonging to fatty acid biosynthetic pathway from A. bauminnii (Binding score: -3.385 kcal/mol) and S. aureus (Binding score: -3.012 kcal/mol) along with FabH from E. coli (Binding score: -4.372 kcal/mol) was undertaken. These theoretical computations indicate Cu-Ag bimetallic NPs as possible inhibitor of selected enzymes. It is suggested that exploring in vitro inhibition potential of these materials may open new avenues for antibiotic discovery.