Phage-Polymer Nanoparticles for Treatment of Antibiotic-Recalcitrant Wound Biofilm Infections - Project Summary Phage-Polymer Nanoparticles for Treatment of Antibiotic-Recalcitrant Wound Biofilm Infections Wound biofilm infections are associated with significant morbidity, mortality, and cost, and can be refractory to conventional antibiotic treatment. The proposed research will create new polymer-phage conjugates to treat wound infections. Phage therapy provides a self-amplifying strategy to combat bacterial infections. However, phages do not efficiently penetrate into the dense biofilm matrix, limiting the efficacy of phage therapies for treating biofilm infections. These issues will be addressed through integration of nanomaterials developed by Rotello with the in vitro, in vivo, and clinical expertise of Patel in phage therapy. In published studies, Rotello and Patel demonstrated that engineered polymers can encapsulate phages to generate non-covalent protein-phage nanoparticles (PPNs) that retain infectivity and feature enhanced efficacy against biofilms relative to free phage in vitro and in vivo. In the proposed research, Rotello will develop new homopolymers and block copolymers to generate polymer-phage conjugates, focusing on Phage K that Patel has shown has cross-strain and cross-species activity. These polymers will use a cationic block to electrostatically anchor the polymer to phages. One PPN family will systematically vary the hydrophobicity of the homopolymer to optimize biofilm penetration and eradication. The second PPN polymer will feature an exterior block with charge-switchable functionality that will go from anionic (non-interacting) to cationic (biofilm penetrating) at biofilm pH, providing targeted delivery of PPN. Conjugates will be screened in vitro against methicillin-resistant Staphylococcus aureus (MRSA) planktonic bacteria and biofilms. Effective PPNs will be incorporated into hydrogels, with hydrogel porosity used to provide controlled PPN delivery. Conjugates effective in vitro will be screened in a realistic murine wound biofilm by Rotello. Patel will then perform pre-clinical studies of the antimicrobial and wound healing efficacy of PPNs, supported by histopathology. Aim 1: Rotello will synthesize homo- and block copolymers and non-covalently conjugate them to phages specific against MRSA study isolates. Infectivity of the conjugates will be quantified and will be tested for biofilm penetration and eradication. Patel will establish cross-strain and cross-species activities of phages. Aim 2. Rotello will incorporate effective PPNs into hydrogels to provide wound dressings with controlled release of phage. Our expectation is that control of hydrogel pore size will regulate PPN release, providing optimal phage activity. Aim 3. Rotello and Patel will use murine wound biofilm models to test PPN-hydrogel wound dressings. These studies will combine parametric pilot experiments using luminescent MRSA by Rotello with full pre-clinical evaluation by Patel. Efficacy in these models will be quantified by decreased bacterial counts, enhanced wound healing, diminished purulence, and decreased inflammation as outcomes.
