Glucose microfluidic biosensors based on reversible enzyme immobilization on photopatterned stimuli-responsive polymer

In this paper, we demonstrate a new strategy for replaceable enzymatic microreactor based on a switchable wettability interface of poly(N-isopropylacrylamide) (PNIPAAm). PNIPAAm porous polymer monolith (PPM) with 3D macroporous framework is photopolymerized in glass microchip within 30 s. The PNIPAAm PPM not only shows its reversible swelling/shrinking property at the different temperature around the lower critical solution temperature (LCST), but also shows reversible hydrophilicity/hydrophobicity corresponding to its swelling/shrinking status. Based on these properties, a biocompatible and replaceable on-chip enzymatic microreactor has been successfully built by means of the reversible adsorption and release of glucose oxidase (GOx) on the robust and stable matrix. Coupled with a carbon fiber microelectrode as electrochemical detector, the microreactor has been successfully employed for detection of glucose with a linear range from 0.05 to 5 mM. This approach may provide a promising way for high efficient and renewable microreactors that will find wide application in clinical diagnosis, biochemical synthesis/analysis, and proteomic research.