PHOTO-BIOMODULATION-INDUCED OXIDATIVE STRESS IN CHRONIC WOUND PATHOGENS: OPTIMIZING LASER PARAMETERS FOR BACTERIAL ERADICATION AND FIBROBLAST PROLIFERATION

Abstract

Chronic wounds colonised by antibiotic-tolerant biofilms represent a growing clinical and economic burden, and light-based therapies have emerged as a promising adjunct that exploits oxidative stress for therapeutic ends. This paper presents a qualitative evidence synthesis of the experimental literature on photobiomodulation (PBM) and related light therapies, examining how irradiation generates oxidative stress in wound pathogens and host cells and how laser parameters might be optimised to achieve the dual goal of bacterial eradication and fibroblast proliferation. Following an integrative review approach, peer-reviewed studies were identified, appraised, and analysed using reflexive thematic synthesis. Six themes were constructed: the mechanistic basis of light-induced oxidative stress; the antimicrobial dimension of short-wavelength light and reactive oxygen species (ROS); the regenerative dimension of red and near-infrared light on fibroblasts; the biphasic dose-response and the therapeutic window; the optimisation of wavelength, fluence, irradiance, and delivery; and translational barriers including biofilms, penetration, and safety. The synthesis indicates a fundamental duality: high, sustained ROS production, achieved chiefly with blue light exciting endogenous porphyrins, drives microbial death, whereas brief, sub-lethal ROS bursts produced by red and near-infrared light activate redox signalling that stimulates fibroblast proliferation and collagen synthesis. These opposing outcomes are governed by the same Arndt-Schulz biphasic principle, implying that wavelength and dose must be selected to maximise the gap between microbial kill and host-cell stimulation. The review concludes that no single parameter set is universally optimal; rather, sequential or combined wavelength strategies, calibrated to wound bioburden and tissue depth, offer the most coherent path toward simultaneous disinfection and regeneration, and it identifies standardisation of dosimetry as the principal research priority.