Assessment of the antibacterial properties of lipoic acid-functionalized silver nanoparticles

Silver nanoparticles (AgNPs) are increasingly explored as alternatives to conventional antibiotics in wound care due to their broad-spectrum antimicrobial activity. This study evaluates the antibacterial performance of α-lipoic acid-functionalized silver nanoparticles (AgNPs-LA) using an integrated experimental-computational approach combining molecular dynamics simulations and experimental validation. AgNPs-LA were synthesized via a controlled hydrothermal method employing biogenic reduction of silver ions to minimize cytotoxicity. Structural and compositional analyses confirmed successful surface functionalization with α-lipoic acid and D-glucose. Morphological characterization revealed predominantly spherical nanoparticles with diameters ranging from 37 to 90 nm. Antimicrobial agar disk diffusion assays demonstrated concentration-dependent inhibition of Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli. Specifically, AgNPs-LA at 40 μg/mL produced inhibition zones statistically comparable to gentamicin against S. aureus and P. aeruginosa (p > 0.05). Molecular dynamics simulations performed under isothermal-isochoric (constant number of particles, volume, and temperature; NVT) canonical ensemble indicated that the disulfide moiety of lipoic acid serves as the primary anchoring group to the silver surface, conferring stability through the formation of a structured hydrophobic surface layer. This interfacial configuration enhances nanoparticle stability and may improve pharmacokinetic clearance, thereby reducing the risk of systemic toxicity. Collectively, these findings highlight the potential of AgNPs-LA as a safe and effective antimicrobial platform for wound management applications.