Heterogeneous Fenton's-like catalyst potentiation of hydrogen peroxide disinfection: an investigation into mechanisms of action.

This study aimed to establish the mechanisms of action (MOA) of a novel surface-functionalised polyacrylonitrile (PAN) catalyst, which was previously shown to have potent antimicrobial activity in conjunction with hydrogen peroxide (H2O2). Bactericidal activity was determined using a disinfectant suspension test. The MOA was investigated by measuring loss of 260nm absorbing material, membrane potential and permeability assays, analysis of intra- and extracellular ATP and pH, and tolerance to sodium chloride and bile salts. The catalyst lowered sub-lethal concentrations of H2O2 from 0.2% to 0.09%. H2O2 ± 3g PAN catalyst significantly (p ≤ 0.05) reduced sodium chloride and bile salt tolerance, suggesting the occurance of sublethal cell membrane damage. The catalyst significantly increased (p ≤ 0.05) N-Phenyl-l-napthylamine uptake (1.51-fold) and leakage of nucleic acids, demonstrating increased membrane permeability. A significant (p ≤ 0.05) loss of membrane potential (0.015 a.u.), coupled with pertubation of intracellular pH homeostasis and depletion of intracellular ATP, suggests potentiation of H2O2-mediated cell membrane damage. This is the first study to investigate the catalyst's antimicrobial mechanism of action, with the cytoplasmic membrane being a target for cellular injury. Understanding the MOA by which the catalyst potentiates H2O2 could lead to optimisation of concentrations and contact times needed for disinfection in a wide range of settings