Thin-Film Polyisocyanide-Based Hydrogels for Affinity Biosensors

A new type of hydrogel thin film that can be post-modified with biofunctional molecules is investigated for possible applications in evanescent wave optical affinity biosensors. This material is based on a polyisocyanide (PIC) copolymer that self-assembles into a fibrous polymer network. It is covalently tethered to a solid transducer surface, and its swelling gives rise to a hydrogel layer with a thickness up to several micrometers, as characterized by a combination of surface plasmon resonance and optical waveguide spectroscopy. Thin PIC-based hydrogel films with pendant functional biomolecules can be used in label-free affinity sensing strategies. In this work, we demonstrate the PIC-based affinity binding matrix through an avidin coupling of functional biomolecules and immunoassay-based detection, which can be readily expanded to other types of assays and target analytes. In addition, the stable PIC matrix proves to be resistant to fouling, even in the presence of complex biological fluids such as blood plasma or serum.