Polymerizable peptide copolymer coatings for the control of biointerfacial interactions

The effective control over biointerfacial interactions is essential for a broad range of biomedical applications in vitro and in vivo such as biosensors, cell culture tools and implantable devices. Here, our aim was to develop a coating strategy that is transferable between different substrate materials and can effectively suppress nonspecific protein adsorption and hence reduce cell attachment while also presenting bioactive signals to enable specific cell-material interactions. In a first step an allylamine plasma polymer coating was applied, followed by the covalent immobilization of a macroinitiator carrying iniferter functionalities in the side chains. Subsequently, copolymers with different molar ratios of acrylamide and a polymerizable peptide containing the sequence Arg-Gly-Asp (RGD) were grafted via surface initiated free radical polymerization. X-ray photoelectron spectroscopy (XPS) was used to confirm the success of each coating step. The cellular response to these coatings was evaluated using L929 mouse fibroblast cell culture assays for up to 24 h. Cell attachment was significantly reduced on acrylamide homopolymer coatings and negative control surfaces representing a polymerizable peptide containing the nonbioactive Arg-Ala-Asp (RAD) sequence. In contrast, cell attachment was increased with increasing polymerizable RGD peptide ratios in the copolymer. The combination of acrylamide-terminated peptide sequences in combination with acrylamide provides a simple and versatile route to surfaces that combine low nonspecific protein adsorption and the display of controlled densities of bioactive signals and is expected to be translated into a number of biomedical applications in vitro and in vivo.