Peptide Functionalized Metallic Nanoconstructs: Synthesis, Structural Characterization, and Antimicrobial Evaluation

Biomolecule based conjugation of metallic nanoparticles has become an important area of research lately especially considering the role of such nanoconjugates in diverse applications. Herein, synthesis of cationic dipeptide conjugated gold/silver nanoparticles through the covalent approach using carbodiimide cross-linker chemistry has been reported. Owing to the exceptional optoelectronic properties of metallic nanoparticles, peptide-gold/silver nanoparticle conjugates were synthesized employing 2-mercaptopropanoic acid as a cross-linker. The conjugates were further compared with their noncovalently synthesized counterparts using ultraviolet-visible spectroscopy. It was generally observed that the conjugates synthesized using the covalent approach were more stable than the conventional noncovalent approach. The synthesized conjugates were further evaluated for their antimicrobial efficacy. The experimental findings demonstrated that peptide capped silver nanoparticles possessed relatively better antimicrobial activity than peptide capped gold nanoparticles, native peptides as well as unconjugated gold/silver nanoparticles which was also evident in time kill assay studies. The morphological effects of active compounds on Escherichia coli and Candida albicans exhibited complete disruption of the cell wall. Thus, this study is an important step toward the opening up of avenues for the applicability of the covalent approach for functionalization of metallic nanoparticles with not only short peptide based systems but also for other biomolecules in areas such as anti-infectives, drug delivery, and bioimaging.