Convenient method for surface modification by patching a freestanding anti-biofouling nanosheet

A convenient method for surface modification is crucially important for the preparation of a functional interface. The precise control of surface properties by chemical and physical approaches is expected to enhance the potential application of innovative nanomaterials. In this study, we propose a methodology for convenient surface modification using a freestanding anti-biofouling ultra-thin film (nanosheet) bearing poly(2-methacryloyloxyethyl phosphorylcholine: MPC) (i.e., pMPC-nanosheets). The physicochemical properties of the pMPC-nanosheet such as physiological stability, surface wettability and anti-biofouling were precisely controlled by means of thermal crosslinking of the nanosheet, the grafting amount of MPC and tuning the thickness of pMPC brushes. These approaches revealed physicochemical insight into the pMPC-nanosheet and its remarkable biological response. The pMPC-nanosheet was prepared via a spin-coating assisted layer-by-layer method in combination with atom transfer radical polymerization of MPC. The freestanding pMPC-nanosheet, comprising an 11 nm-thick pMPC brushed layer with a hydrophilic surface, was easily transferred by tweezers, cut by scissors, patterned by a needle and patched onto various interfaces with the aid of a water-soluble supporting film. The pMPC-nanosheets patched on cell culture substrates displayed anti-biofouling properties such as anti-coagulant activity against human whole blood as well as the potential to microscopically pattern murine fibroblast cells. The present study not only reveals physicochemical properties of the surface-functionalized nanosheet for biological application, but also constitutes an alternative approach to conventional lithographic techniques using photoresists and micro-patterned molds; thereby providing a new tool in the field of nanobiotechnology.