Highly efficient and selective antimicrobial isonicotinylhydrazide-coated polyoxometalate-functionalized silver nanoparticles

With the rapidly approaching post-antibiotic era, new and effective combinations of antibiotics are imperative to combat multiple drug resistance (MDR). We have synthesized multimodal antimicrobials that integrate the antibiotic isonicotinylhydrazide (INH), silver nanoparticles (AgNPs^INH), and two different polyoxometalates (POMs) namely, phosphotungstic acid (PTA) and phosphomolybdic acid (PMA) to prepare AgNPs^INH@PTA and AgNPs^INH@PMA, respectively. AgNPs^INH have peroxidase-like (nanozyme) activity and very high antibacterial potential toward S. aureus, which was further enhanced upon modification with POMs. The selectivity of these functional nanozymes was evaluated with m5S mouse fibroblasts using WST-8, LDH viability, in vitro reactive oxygen species (ROS) generation assays, and crystal violet morphological studies. These investigations showed very low cytotoxicity for the nanoparticles compared to free metal ions (Ag⁺), pristine POMs and INH, demonstrating the ability of multifunctional materials to provide efficient and selective antimicrobials.