Switchable bacteria-killing and bacteria-releasing surface fabricated from regenerable PNIPAM-based N-halamine cotton fabrics

So far, more and more multifunctional antibacterial materials qualified with "bacteria-killing" and "bacteria -releasing" capacities have been developed by researchers to kill live bacteria and release the killed bacteria. However, most of these surfaces are biologically incompatible and have a complex production process. In this work, we created a PNIPAM-based N-halamine cotton fabric via simple Si-ATRP (surface-initiated atom transfer radical polymerization) and chloridized in ordinary diluted sodium hypochlorite solutions. Notably, the N-Cl bond at N-halamine cotton fabrics and the N-H bond at PNIPAM can interconvert with each other easily. The N-Cl bond provides the possibility of bacteria-killing. Simultaneously, the N-H bond can change the surface wettability and cooperate with the stretch of PNIPAM chains at a lower temperature, providing the ability of bacteria-releasing. As a result, the PNIPAM-based N-halamine cotton fabrics have excellent antibacterial effi-ciency in the form of "N-Cl" and a remarkable bacteria-releasing efficiency in the form of "N-H". In addition, the functional surface has good biocompatibility. Overall, we develop an easy way to create switchable "bacteria -killing" and "bacteria-releasing" cotton fabrics, and this smart surface shows a potential application in biomedical and hospital surfaces.