Paper Title
Cationic Silver Nanoclusters as Potent Antimicrobials against Multidrug Resistant Bacteria

Abstract
Bacterial multidrug resistance (MDR) is a serious healthcare issuecaused bythe long-term sub-therapeutic clinical treatment of infectious diseases.Nanoscale engineering of metal nanoparticles has great potential to address this issue by tuning the nano-bio interface to target bacteria. Herein, we report the use of branched polyethylenimine functionalized (bPEI) silver nanoclusters (bPEI-Ag NCs) to selectively kill MDR pathogenic bacteria by combining the antimicrobial activity of silverwith the selective toxicity of bPEI towards bacteria.Minimum inhibitory concentration (MIC) of bPEI-Ag NCs was determined against 12 uropathogenic (pathogens of urinary tract)MDR strains and found to be10-15-foldlower than that of PEI and 2-3-fold lower thanthat of AgNO3 alone.Cell viability and hemolysis assays demonstrated biocompatibility of bPEI Ag NCs with human fibroblasts and red blood cells, with selective toxicity against MDR bacteria. Keywords - Silver Nanoclusters, Polyethylenimine, Multidrug Resistance, Pathogenic Bacteria, Biocompatibility