Enhancement of Vancomycin Potential against Pathogenic Bacterial Strains via Gold Nano-Formulations: A Nano-Antibiotic Approach

The remarkable rise of antibiotic resistance among pathogenic bacteria poses a significant threat to human health. Nanoparticles (NPs) have recently emerged as novel strategies for conquering fatal bacterial diseases. Furthermore, antibiotic-functionalized metallic NPs represent a viable nano-platform for combating bacterial resistance. In this study, we present the use of vancomycin-functionalized gold nanoparticles (V-GNPs) to battle pathogenic bacterial strains. A facile one-pot method was adopted to synthesize vancomycin-loaded GNPs in which the reducing properties of vancomycin were exploited to produce V-GNPs from gold ions. UV–Visible spectroscopy verified the production of V-GNPs via the existence of a surface plasmon resonance peak at 524 nm, whereas transmission electron microscopy depicted a size of ~24 nm. Further, dynamic light scattering (DLS) estimated the hydrodynamic diameter as 77 nm. The stability of V-GNPs was investigated using zeta-potential measurements, and the zeta potential of V-GNPs was found to be −18 mV. Fourier transform infrared spectroscopy confirmed the efficient loading of vancomycin onto GNP surfaces; however, the loading efficiency of vancomycin onto V-GNPs was 86.2%. Finally, in vitro antibacterial studies revealed that V-GNPs were much more effective, even at lower concentrations, than pure vancomycin. The observed antibacterial activities of V-GNPs were 1.4-, 1.6-, 1.8-, and 1.6-fold higher against Gram-negative Escherichia coli, Klebsiella oxytoca, and Pseudomonas aeruginosa and Gram-positive Staphylococcus aureus, respectively, compared to pure vancomycin. Collectively, V-GNPs represented a more viable alternative to pure vancomycin, even at a lower antibiotic dose, in conquering pathogenic bacteria.