Shaped core/shell polymer nanoobjects with high antibacterial activities via block copolymer microphase separation

We report a procedure to fabricate antibacterial core/shell polymer nanoobjects with sheetlike, cylindrical, and spherical shapes. These shaped nanoobjects with chemically cross-linked polysiloxane cores and densely grafted polyammoniums shells were prepared by dispersing cross-linked microphase-separated materials of diblock copolymers, poly(2-(dimethylamino)ethyl methacrylate)-block-poly(3-(triethoxysilyl)propyl methacrylate) (PDMAEMA-b-PTEPM). Shapes of the nanoobjects were controlled by block copolymer composition, namely the microphase-separated structures. Then the tethered PDMAEMA shells were further quaternized with n-octyl bromide. The diblock copolymers, microphase-separated materials and shaped nanoobjects before and after quaternization were studied by 1H NMR, size exclusion chromatography (SEC), small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM), and Fourier-transform infrared spectroscopy (FT-IR). The antibacterial activities of these quaternized nanoobjects have been preliminarily assessed against bacteria Escherichia coli (E. coli) (8099). The minimum bactericidal concentration (MBC) of the sheets, cylinders and spheres were 1.00, 0.66, 0.66 mg/mL. The antibacterial activities of the quaternized nanoobjects were nearly ten times higher than that of quaternized PDMAEMA homopolymer.