Exploration of Copper-Cysteamine Nanoparticles as a New Type of Agents for Antimicrobial Photodynamic Inactivation

Copper-cysteamine (Cu-Cy) nanoparticles (NPs) are a new type of sensitizers that can be activated by UV light, X-rays, microwaves and ultrasound to produce reactive oxygen species for cancer treatment. Here, for the first time, we explored Cu-Cy NPs for bacteria inactivation by treating gram-positive bacteria (methicillin-resistant <i>Staphylococcus aureus</i> and <i>Enterococcus faecalis</i>) and gram-negative bacteria (<i>Escherichia coli</i> and <i>Acinetobacter baumannii</i>), respectively. The results show that Cu-Cy NPs are very effective in killing gram-positive bacteria but are quite limited in killing gram-negative bacteria yet. The major killing mechanism is cell damage by singlet oxygen and Cu-Cy NPs are potential agents for bacteria inactivation.