Semi-Interpenetrating Polyurethane Network Foams Containing Highly Branched Poly(N-Isopropyl Acrylamide) With Vancomycin Functionality

Highly branched poly(N-isopropylacrylamide) (HB-PNIPAM), functionalized with vancomycin at the chain ends, acted as a bacterial adhesive and was incorporated into polyurethane foams to form semi-interpenetrating networks. PNIPAM was labeled with a solvatochromic dye, Nile red. It was found that the thermal response of the polymer was dependent on the architecture, and temperature-dependent color changes were observed within the foam. The foams had open pore structures, and the presence of HB-PNIPAM substantially reduced the shrinkage of the foam as the temperature was increased up to 20 degrees C. The foams were selectively adhesive for Staphylococcus aureus (Gram-positive bacteria) compared to Pseudomonas aeruginosa (Gram-negative bacteria), and the presence of S. aureus was indicated by increased fluorescence intensity (590-800 nm).