Flow-injection amperometric glucose biosensors based on graphene/Nafion hybrid electrodes

Graphical abstract: Amperometric biosensors based on graphene hybrids showed the fast, sensitive, and stable amperometric responses in the flow injection system for automatically monitoring glucose. Display Omitted Highlights: → Flow-injection amperometric glucose biosensors were fabricated using reduced graphene oxide/Nafion hybrids. → The electrochemical kinetics of biosensors were comprehensively investigated by analysing electron transfer rate, charge transfer resistance, and ion diffusion coefficient, respectively. → The biosensors exhibited the fast, sensitive, and stable amperometric responses in the flow injection system for detecting glucose. - Abstract: In this research, we demonstrated the fabrication of flow-injection amperometric glucose biosensors based on RGO/Nafion hybrids. The nanohybridization of the reduced graphene oxide (RGO) by Nafion provided the fast electron transfer (ET) for the sensitive amperometric biosensor platforms. The ET rate (ks) and the charge transfer resistance (RCT) of GOx-RGO/Nafion hybrids were evaluated to verify the accelerated ET. Moreover, hybrid biosensors revealed a quasi-reversible and surface controlled process, as confirmed by the low peak-to-peak (ΔEp) and linear relations between Ip and scan rate (ν). Hybrid biosensors showed the fast response time of ∼3 s, the sensitivity of 3.8 μA mM-1 cm-2, the limit of detection of 170 μM, and the linear detection range of 2-20 mM for the flow-injection amperometric detection of glucose. Furthermore, interference effect of oxidizable species such as ascorbic acid (AA) and uric acid (UA) on the performance of hybrid biosensors was prevented at the operating potential of -0.20 V even under the flow injection mode. Therefore, the fast, sensitive, and stable amperometric responses of hybrid biosensors in the flow injection system make it highly suitable for automatically monitoring glucose.