A novel glucose biosensor based on the immobilization of glucose oxidase on layer-by-layer assembly film of copper phthalocyanine functionalized graphene

A negatively charged glassy carbon electrode (GCE) was formed through the electrochemical modification of sulfanilic acid (ABS). Subsequently, graphene composites functionalized with copper phthalocyanine-3,4′,4″,4‴-tetrasulfonic acid tetrasodium salt (TSCuPc) or alcian blue pyridine variant (AB) were assembled layer-by-layer (LbL) via alternate electrostatic adsorption onto the ABS/GCE surface to obtain a uniform and stable graphene multilayer film modified electrode. With glucose oxidase (GOD) as an enzyme model, a novel GOD/Nafion/(LbL)3.5/ABS/GCE electrochemical biosensor has been developed. SEM and Raman spectra were utilized to characterize the functionalized graphene nanocomposites and modified electrodes. The electrochemical performance of the biosensor was investigated by cyclic voltammetry. The results demonstrated that the graphene multilayer film significantly enhanced the electrocatalytic activity of the modified electrode toward O2 reduction. Based on the O2 consumption during the oxidation process of glucose, the as-prepared biosensor exhibited a low detection limit of 0.05 mmol L−1, excellent reproducibility, stability, sensitivity and selectivity, and its response was linear up to 8 mmol L−1 glucose concentration. Accordingly, the multilayer film consisting of copper phthalocyanine functionalized graphene nanocomposites offers a novel and effective platform for the electrochemical biosensing applications.