J. Hopf, C. Kudary, S. Lee, D. Donahue, V. Ploplis, F.J. Castellino, P. Nallathamby
Berthiaume Institute for Precision Health / University of Notre Dame,
United States
Keywords: antibiofilm, phage-mimicking nanoparticles, anti MDR, anti AMR, ESKAPEE
Summary:
Statement of Purpose: Implant‑associated infections and chronic wounds persist because surface‑attached biofilms shield bacteria from antibiotics and host defenses. We engineered phage‑architecture antibacterial nanoparticles (PhANPs; silica cores decorated with silver‑alloyed gold nanospheres, with or without cysteine‑bearing antimicrobial peptides) to disrupt biofilm structure, kill embedded cells, and prevent re‑colonization. Here we emphasize anti‑biofilm performance in rat wound infections and as immobilized coatings on implant‑grade steel. Methods: ANPs and peptide‑capped pep@ANPs were tested in solution and as covalently immobilized coatings. In vitro biofilms of MRSA, P. aeruginosa, E. faecalis, C. striatum, K. pneumoniae, carbapenem‑resistant A. baumannii, and S. epidermidis were grown on steel coupons. Biofilm burden was quantified by CFU recovery, biomass staining, and confocal LIVE/DEAD imaging after single or repeated challenges. For in vivo studies, rat dorsal wounds were inoculated with MRSA or carbapenem‑resistant A. baumannii and treated topically with BANP@Syn20 versus peptide alone or vehicle for 12 days; wound area and bacterial burden were tracked. Antibiotic re‑sensitization was evaluated with sub‑MIC ertapenem or ceftriaxone. Results: On implants: Immobilized pep@ANP coatings delivered complete on‑contact killing of bacteria reaching the surface and prevented maturation of surface‑attached biofilms across multiple challenge cycles. When pre‑established biofilms were present, the coatings and brief rinses with PhANPs rapidly reduced viable biomass, leaving no recoverable CFUs on coupons and blocking regrowth on the same surface. These effects were observed across Gram‑positive and Gram‑negative species, consistent with the platform’s ≥5‑log bactericidal capacity in solution and its architectural advantage when immobilized. In rat wounds: BANP@Syn20 accelerated closure of MRSA‑ and carbapenem‑resistant A. baumannii wounds and maintained low bacterial burden throughout the course, consistent with disruption of wound‑associated biofilms rather than transient planktonic killing. Co‑treatment with ertapenem or ceftriaxone further depressed growth curves relative to antibiotic alone, indicating relief of biofilm‑associated tolerance and re‑sensitization to legacy agents. Extended passaging for >1,000 bacterial generations did not yield resistance under 2×MIC nanoparticle exposure, supporting sustained anti‑biofilm efficacy. Cytocompatibility with HaCaT and MG‑63 cells and favorable histology in mice support local use on implants and in wounds. Conclusions: PhANPs combine immediate bactericidal action with robust anti‑biofilm performance on implants and in rat wound infections. As stable surface coatings, they prevent biofilm establishment and eradicate adherent communities; as topical agents, they dismantle mature biofilms and speed wound healing. The platform reduces peptide dosing, re‑sensitizes recalcitrant pathogens to existing antibiotics, and shows no detectable resistance development under supra‑MIC exposure—positioning it for translation to infection‑resistant implants and advanced wound care.