Porphyrin Functionalized Gelatin Nanoparticle-Based Biodegradable Phototheranostics: Potential Tools for Antimicrobial Photodynamic Therapy

Photomedicine-based antimicrobial therapy has emerged as an alternative treatment for antibiotic-resistant microbial infections. Although various photosensitizers (PSs) have been reported as efficient antimicrobial agents, their efficient delivery to the specific target area requires further investigation. In the current study, development of a biodegradable phototheranostic nanoagent (PTNA) by incorporation of a PS (trans-AB-porphyrin) and gelatin nanomatrix is described. The antimicrobial efficacy of the PTNA against Gram-positive bacteria, Gram-negative bacteria, and yeast strains, along with other properties including hydrophilicity, biocompatibility, and targeting ability, is evaluated. Unlike the commonly used membrane permeabilizing chemicals that are toxic, the delivery vehicle gelatin used in this study is biocompatible and biodegradable. Here, the method offers a sustainable synthesis of gelatin-based stable formulation of nanotheranostic agents with high loading (>85%). The study revealed that the reactive oxygen species (ROS), generated in situ by the PTNAs, are primarily responsible for microbial cell death. The developed PTNAs described herein featured "nano size (<200 nm), have high fluorescence and singlet oxygen quantum yields, retain photophysical properties of PS after incorporation into the gelatin matrix, could be activated by a cost-effective light irradiation, and have efficient antimicrobial photodynamic activity." This antimicrobial photodynamic therapy using the newly synthesized phototheranostic nanoagent has manifested its competence, therapeutic modality of general acceptance, and wide-spectrum antimicrobial action.