Visible-light activated photodegradation of DNA and lipid membranes by nitrogen-doped titanium dioxide-gold nanorods composites

Abstract

The growing challenge of antibiotic resistance calls for alternative therapeutic strategies beyond conventional antibiotics. Antibacterial Photodynamic Therapy (aPDT), based on the light-induced generation of Reactive Oxygen Species (ROS), offers a non-specific approach that is detrimental to bacterial cells at multiple levels. Here, we explore the photocatalytic properties of nitrogen-doped titanium dioxide (N-TiO2) and compare them with those of the N-TiO2/AuNRs composite, a colloidal hybrid system formed by combining N-TiO2 with gold nanorods (AuNRs) upon excitation with a blue visible light centered at 420 nm. The synthesized materials underwent thorough in-depth morphological characterization to investigate their structural and functional features. Their photocatalytic activity was first evaluated using methyl orange as a model molecule, and subsequently on DNA and model lipid membranes, key components of bacterial life. Spectroscopic techniques were employed to highlight details on the oxidative damages at the molecular level. Scavenging experiments were performed to identify the reactive species involved in the photocatalytic process. The results highlight the potential of the composite N-TiO2/AuNRs as promising agent for photodynamic therapy, providing insights into how oxidative processes alter molecular targets.