Phage-guided rapid enrichment of copper-protocatechuic acid nanoparticles for targeted antibacterial therapy

The effective treatment of bacterial infections requires rapid and selective enrichment of antibacterial agents on bacterial surfaces within infectious microenvironments. Transition metal ion-based antibacterial agents show broad-spectrum bactericidal activity, but they usually rely on passive diffusion and stochastic bacterial contact, limiting their ability to establish sufficient local doses within short treatment windows. Herein, an M13 phage-mediated targeting strategy was developed for the rapid enrichment and delivery of copper ion-protocatechuic acid nanoparticles (CP NPs). Through phage display, an M13 phage targeting methicillin-resistant Staphylococcus aureus (MRSA-targeting phage, MTP) and an M13 phage targeting Pseudomonas aeruginosa (P. aeruginosa-targeting phage, PTP) were identified. MTP and PTP retained the typical filamentous morphology of M13 phage and selectively adhered to corresponding bacteria within 1 min. Protocatechuic acid (PCA) was then used as a polyphenolic bridge for phage-surface adhesion and Cu²⁺ coordination, yielding CP@MTP and CP@PTP, which integrate bacterial recognition, metal-polyphenol assembly, and copper-based antibacterial activity into filamentous delivery scaffolds. After only 10 min of bacterial exposure, CP@MTP selectively reduced MRSA by 3 log, while CP@PTP reduced P. aeruginosa by 1.7 log, likely owing to rapid phage-mediated CP NP enrichment on bacterial surfaces. Transcriptomic analysis further revealed bacterial stress responses induced by targeted copper delivery. In zebrafish larval tail-fin infection models, CP@MTP and CP@PTP effectively eradicated corresponding bacteria and reduced neutrophil recruitment. In a murine P. aeruginosa pneumonia model, CP@PTP prolonged lung retention, reduced pulmonary bacterial burden, and alleviated inflammatory lung injury. This study establishes targeted M13 phages as spatial regulators for rapid and precision antibacterial therapy.