A Modifiable, Spontaneously Formed Polymer Gel with Zwitterionic and N-Hydroxysuccinimide Moieties for an Enzymatic Biofuel Cell

Abstract

A modifiable, spontaneously formed and biocompatible polymer gel, composed of phosphorylcholine and N-hydroxysuccinimide ester, is reported, which can be subjected to postmodification by amine-containing mediators to obtain a redox zwitterionic gel. Owing to attractive interactions between the polymer chains, the network structure of the polymer gel is formed spontaneously in ethanol or water. In addition, the designed hydrogel can serve as an enzyme-immobilizing matrix for enzymatic bioelectrodes. We illustrate the potential applications of the hydrogel with a biofuel cell that demonstrated superior operational stability over 10 days and the unaffected current of the bioelectrode in concentrated protein solution (45 mg mL–1). Compared with a typical redox hydrogel, the zwitterionic moieties with high hydration endow the redox zwitterionic hydrogel with (i) better environment for preserving enzyme’s activity and (ii) resistance to biofouling caused by protein adsorption. These properties contribute to overcoming the most challenging issues in the field of implantable bioelectronic applications, as insufficient operational stability and lack of biocompatibility severely limit their feasibility for practical applications.