Tryptophan-Rich Short Peptide Amphiphile-Mediated Synthesis of Silver Nanoparticles for Potent Antibacterial...

This study introduces a simple, eco-friendly, and biocompatible method for synthesizing hybrid antibacterial nanostructures using tryptophan-rich short peptide amphiphile (sPA). This sPA serve a dual role as both reducing and stabilizing agent for silver nanoparticles (AgNPs). Designed with self-assembling capabilities, the sPA spontaneously form polydispersed heterogeneous supramolecular nanostructures and simultaneously enable the in situ photoreduction of Ag(I) ions under mild sunlight exposure, owing to the intrinsic photophysical and redox-active properties of tryptophan residues. The resulting AgNP-sPA hybrids display well-defined polydispersed morphologies, confirmed through detailed spectroscopic and microscopic analyses. These nanoconjugates show excellent colloidal stability and strong interactions with bacterial membranes. Antibacterial assessments reveal that the AgNP-sPA hybrids exhibit potent and broad-spectrum activity against both Gram-positive (e.g., Staphylococcus aureus) and Gram-negative pathogens, including Escherichia coli (standard and clinical strains), Klebsiella pneumoniae, Acinetobacter baumannii, and Pseudomonas aeruginosa. Notably, the hybrids demonstrate superior efficacy compared to the conventional antibiotic levofloxacin. Importantly, the AgNP-sPA nanostructures also exhibit significant inhibitory activity against multidrug-resistant strains such as methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Staphylococcus aureus (VRSA), highlighting their potential in tackling antibiotic-resistant infections.