The long term success of implanted biomaterials and devices is often dependent on their interactions with host immune system. The unfavorable biological response to implanted materials can elicit a cascade of host immune responses, compromising device performance and ultimately leading to device failure. In an attempt to develop more biocompatible materials and devices, several methods have been reported to modify implant surfaces with synthetic and natural polymer-based coatings to resist host immune responses. However, surface modification of materials can be challenging, requiring surface-specific multi-step protocols. Therefore, there is a critical need for the development of simple and universal coating methods to modify the surfaces of broad range of implantable biomaterials.
Yesilyurt et al. from Massachusetts Institute of Technology, USA has demonstrated surface modification of model devices with an anti-biofouling zwitterionic polymer using a facile and scalable methodology. This approach employs first modification of the surfaces with mussel-inspired polydopamine (PDA) films, followed by conjugation of phosphoryl choline (PC) zwitterionic polymer to this PDA layer. PC polymer was selected based on its superior anti-biofouling properties to prevent non-specific protein adsorption. Authors showed that coating of alginate microspheres, commonly used for cell transplantation and tissue engineering applications, with PC zwitterionic polymer through mussel-mimetic catecholamine polymer thin films improves the in vivo biocompatibility of alginate implant by reducing the surface-mediated fibrotic reactions in vivo. Since this coating method is material-independent, the versatility of dopamine mediated surface modification has been shown by coating other solid materials, such as polystyrene (PS) microspheres, a model material known to produce robust immune responses.
Based on the results, this approach to surface modification with zwitterionic polymers can be applied to virtually any implantable biomaterial, with broad use for cell transplantation, drug delivery and biomedical device transplantation.