Photothermal Killing of Methicillin-Resistant Staphylococcus aureus by Bacteria-Targeted Polydopamine Nanoparticles with Nano-Localized Hyperpyrexia

Bacterial infections caused by antibiotic-resistant pathogens have become intractable problems to public health. Therefore, there is an imperious demand for developing new approaches to effectively kill antibiotic-resistant bacteria. In this work, we report a kind of bacteria-targeted polydopamine nanoparticle exhibiting great photothermal killing ability toward methicillin-resistant Staphylococcus aureus (MRSA) by nano-localized hyperpyrexia under low-power near-infrared (NIR) light irradiation. These bacteria-targeted nanoparticles (PDA-PEG-Van) are prepared by modifying polydopamine nanoparticles with thiol-poly(ethylene glycol) (mPEG-SH) and vancomycin (Van) molecules. The PEG shell endows the nanoparticles with excellent long-term circulation stability. Due to the multivalent hydrogen-bond interactions between vancomycin and the MRSA cell wall, the vancomycin-modified polydopamine nanoparticles can specifically target MRSA rather than mammalian cells. These bacteria-targeted nanoparticles are employed as a nano-localized heat source to kill MRSA via disrupting the bacterial cell wall and membrane under irradiation of low-power NIR light. More importantly, the surrounding healthy tissues suffer bare damage, owing to the absence of any targeting effect of PDA-PEG-Van toward mammalian cells and the low power of NIR light used in the therapeutic process. Given the above advantages, the bacteria-targeted polydopamine nanoparticles proposed in this work show tremendous potential to treat MRSA infections, because they can effectively limit localized heating in the infection sites to kill bacteria and cut down damage to healthy tissues.