Fabrication of a highly effective electrochemical urea sensing platform based on urease-immobilized silk fibroin scaffold and aminated glassy carbon electrode

Abstract

A glassy carbon electrode (GCE) was successfully functionalized with amine groups ([sbnd]NH2) through the electrooxidation of carbamic acid, to produce an aminated GCE. The aminated GCE could be effectively used to detect current changes during the urease-catalyzed decomposition of urea. The silk fibroin (SF) scaffolds were used to place urease near the surface of the aminated GCE (urease/SF/aminated GCE). The prepared electrode was employed for electrochemical urea sensing utilizing cyclic voltammetry and amperometry techniques. The fabricated sensing platform displayed rapid detection response and high sensitivity of 112.3 μA mM−1 cm−2 with a linear correlation between current and urea concentrations (0.3–2.7 mM). Values for limit of detection (LOD) and limit of quantification (LOQ) were estimated to be 0.163 mM and 0.394 mM, respectively. The reproducible sensing responses recorded using the urease/SF/aminated GCE comprising replaceable SF discs (generated and functionalized with urease in the same batch) assure the suitability of the present platform for application in urea sensing devices. © 2017 Elsevier B.V.