Enzyme responsive hyaluronic acid nanocapsules containing polyhexanide and their exposure to bacteria to prevent infection.

Antibacterial nanodevices could bring coatings of plastic materials and wound dressings a big step forward if the release of the antibacterial agents could be triggered by the presence of the bacteria themselves. Here, we show that novel hyaluronic acid (HA)-based nanocapsules containing the antimicrobial agent polyhexanide are specifically cleaved in the presence of hyaluronidase, a factor of pathogenicity and invasion for bacteria like Staphylococcus aureus and Escherichia coli. This resulted in an efficient killing of the pathogenic bacteria by the antimicrobial agent. The formation of different polymeric nanocapsules was achieved through a polyaddition reaction in inverse miniemulsion. After the synthesis, the nanocapsules were transferred to an aqueous medium and investigated in terms of size, size distribution, functionality, and morphology using dynamic light scattering, zeta potential measurements and scanning electron microscopy. The enzyme triggered release of a model dye and the antimicrobial polyhexanide was monitored using fluorescence and UV spectroscopy. The stability of the nanocapsules in several biological media was tested and the interaction of nanocapsules with human serum protein was studied using isothermal titration calorimetry. The antibacterial effectiveness is demonstrated by determination of the antibacterial activity and determination of the minimal bactericidal concentration (MBC).