Bacterial Toxin-triggered Drug Release from Gold Nanoparticle-stabilized Liposomes for the Treatment of Bacterial Infection

We report a new approach to selectively deliver antimicrobials to the sites of bacterial infections by utilizing bacterial toxins to activate drug release from gold nanoparticle-stabilized phospholipid liposomes. The binding of chitosan-modified gold nanoparticles to the surface of liposomes can effectively prevent them from fusing with one another and from undesirable payload release in regular storage or physiological environments. However, once these protected liposomes "see" bacteria that secrete toxins, the toxins will insert into the liposome membranes and form pores, through which the encapsulated therapeutic agents are released. The released drugs subsequently impose antimicrobial effects on the toxin-secreting bacteria. Using methicillin-resistant Staphylococcus aureus (MRSA) as a model bacterium and vancomycin as a model anti-MRSA antibiotic, we demonstrate that the synthesized gold nanoparticle-stabilized liposomes can completely release the encapsulated vancomycin within 24 h in the presence of MRSA bacteria and lead to inhibition of MRSA growth as effective as an equal amount of vancomycin-loaded liposomes (without nanoparticle stabilizers) and free vancomycin. This bacterial toxin enabled drug release from nanoparticle-stabilized liposomes provides a new, safe, and effective approach for the treatment of bacterial infections. This technique can be broadly applied to treat a variety of infections caused by bacteria that secrete pore-forming toxins.