Stealth Bacteria Fighters Have Golden Stability

Researchers at the University of California, San Diego, have designed a new way to selectively deliver antimicrobial agents to the sites of bacterial infections. Liangfang Zhang and coworkers use chitosan-coated gold nanoparticles to stabilize phospholipid liposomes that are loaded with antibiotics (J. Am. Chem. Soc., DOI: 10.1021/ja111110e). Toxins secreted by bacteria poke holes in these liposomes, releasing the antibiotics directly at the site of infection. The gold nanoparticles are key to the drug delivery strategy, the researchers point out. Without them, the liposomes have a short shelf life because they tend to fuse uncontrollably, thereby losing their payload prematurely. To demonstrate the bacterial fighting power of the nano-enhanced liposomes, Zhang’s team loaded them with vancomycin and applied them to methicillin-resistant Staphylococcus aureus. Within 24 hours, the liposomes inhibited bacterial growth as effectively as vancomycin on its own. “This antimicrobial drug delivery approach provides an entirely new paradigm for the treatment of bacterial infections by specifically releasing drugs at the infectious sites, while minimizing possible off-target effects,” the researchers write.