Biofilm-Binding Phages Enhance Biofilm Eradication by Synergistic Photothermal and Photodynamic Therapy.

Biofilms, a major cause of chronic bacterial infections, present significant treatment challenges due to their protective extracellular matrix that shields bacteria from both antibiotics and host immune defenses. To treat biofilms more effectively, here we discovered a biofilm-binding peptide from a phage library and verified that it selectively bound the polysaccharides on the biofilm. We then engineered M13 phage into trifunctional nanofibers displaying the biofilm-binding peptide at the tip and carrying gold nanoparticles (AuNPs, as photothermal agents) and tetrakis(4-carboxyphenyl) porphyrin (TCPP, as a photosensitizer) on the sidewall for combined phototherapy. This design enhances binding/anchoring and eradication of biofilms by leveraging the unique properties of each component. The phage nanofibers efficiently bound biofilms and promoted the transfer of heat and penetration of reactive oxygen species (ROS) into the biofilm, leading to cell death. Therefore, under light irradiation, the engineered phage nanofibers effectively eradicated the biofilms by AuNP-induced photothermal therapy (PTT) and TCPP-assisted photodynamic therapy (PDT) in a biofilm-associated skin wound model. Transcriptomic profiling suggests stress-response signatures consistent with oxidative/thermal injury. This study presents a promising ternary synergistic strategy for eradicating biofilms, potentially improving clinical outcomes in wound infection management.