A near-infrared broad-spectrum antimicrobial nanoplatform powered by bacterial metabolic activity for enhanced antimicrobial photodynamic-immune therapy

Abstract

The emergence of antimicrobial-resistant bacterial infections poses a significant threat to public health, necessitating the development of innovative and effective alternatives to antibiotics. Photodynamic therapy (PDT) and immunotherapy show promise in combating bacteria. However, PDT's effectiveness is hindered by its low specificity to bacteria, while immunotherapy struggles to eliminate bacteria in immunosuppressive environments. In this work, we introduce an innovative near-infrared antimicrobial nanoplatform (ZFC) driven by bacterial metabolism. ZFC, comprising d-cysteine-functionalized pentafluorophenyl bacteriochlorin (FBC-Cy) coordinated with Zn²⁺, is designed for antimicrobial photodynamic-immune therapy (aPIT) against systemic bacterial infections. By specifically targeting bacteria via d-amino acid incorporation into bacterial surface peptidoglycans during metabolism, ZFC achieves precise bacterial clearance in wound and pulmonary infections, exhibiting an antimicrobial efficacy of up to 90 % with minimal damage to normal cells under 750 nm light. Additionally, ZFC enhances the activation of antigen-presenting cells by 3.2-fold compared to control groups. Furthermore, aPIT induced by ZFC triggers systemic immune responses and establishes immune memory, resulting in a 1.84-fold increase in antibody expression against bacterial infections throughout the body of mice. In conclusion, aPIT prompted by ZFC presents a approach to treating bacterial infections, offering a broad-spectrum solution for systemic bacterial infections. STATEMENT OF SIGNIFICANCE: The new concept demonstrated focuses on an innovative near-infrared antimicrobial nanoplatform (ZFC) for antimicrobial photodynamic-immune therapy (aPIT), highlighting its reliance on bacterial metabolism and its non-damaging effect on normal tissues. ZFC efficiently targets deep-tissue bacterial infections by harnessing bacterial metabolism, thereby enhancing therapeutic efficacy while sparing normal tissues from harm. This approach not only clears bacterial infections effectively but also induces potent adaptive immune responses, leading to the eradication of distant bacterial infections. By emphasizing ZFC's unique mechanism driven by bacterial metabolism and its tissue-sparing properties, this work underscores the potential for groundbreaking advancements in antimicrobial therapy. Such advancements hold promise for minimizing collateral damage to healthy tissues, thereby improving treatment outcomes and mitigating the threat of antimicrobial resistance. This integrated approach represents a significant progress forward in the development of next-generation antimicrobial therapies with enhanced precision and efficacy.

Keywords: Antimicrobial photodynamic-immune therapy; Bacterial metabolism; Systemic bacterial infections.