Controlled release and antibioticeffect of vancomycin-loaded poly( <i>N</i> -isopropylacrylamide) nanoparticles as a smart drug delivery system

Numerous studies have addressed the use of vancomycin (VA) to effectively treat bacterial infections. However, VA is known to cause side effects when administered intravenously. Herein, monodisperse poly(<i>N</i>-isopropylacrylamide) (PNIPAAm) hollow nanocapsules were synthesized at the interface of a water-in-oil (W/O) single emulsion via Shirasu porous glass (SPG) membrane emulsification and UV-initiated polymerization. In water solutions, the PNIPAAm nanocapsules were able to encapsulate VA and form a new nanoscale water-soluble drug delivery system, namely, PNIPAAm-VA. In vitro experiments showed that PNIPAAm and PNIPAAm-VA had no cytotoxicity toward human bone marrow mesenchymal stem cells. In addition, the slow hydrolysis of PNIPAAm-VA in vitro led to the progressive release of VA, which was discharged at more than 50% and 80% of its initial concentration within 10 days at 37°C and 40°C, respectively; this subsequently inhibited the growth of methicillin-resistant Staphylococcus aureus bacteria. We believe that our PNIPAAm-VA nanoparticles can potentially be used as an effective injectable for temperature-sensitive materials in vivo to achieve the localized controlled release of drugs as safe and specific therapeutic agents.