Abstract
Continuous intensive monitoring of glucose is one of the most important approaches in recovering the quality of life of diabetic patients. One challenge for electrochemical enzymatic glucose sensors is their short lifespan for continuous glucose monitoring. Therefore, it is of great significance to develop non-enzymatic glucose sensors as an alternative approach for long-term glucose monitoring. This study presented a highly sensitive and selective electrochemical non-enzymatic glucose sensor using the electrochemically activated conductive Ni3(2,3,6,7,10,11-hexaiminotriphenylene)2 MOFs as sensing materials. The morphology and structure of the MOFs were investigated by scanning SEM and FTIR, respectively. The performance of the activated electrode toward the electrooxidation of glucose in alkaline solution was evaluated with cyclic voltammetry technology in the potential range from 0.2 V to 0.6 V. The electrochemical activated Ni-MOFs exhibited obvious anodic (0.46 V) and cathodic peaks (0.37 V) in the 0.1 M NaOH solution due to the Ni(II)/Ni(III) transfer. A linear relationship between the glucose concentrations (ranging from 0 to 10 mM) and anodic peak currents with R2 = 0.954 was obtained. It was found that the diffusion of glucose was the limiting step in the electrochemical reaction. The sensor exhibited good selectivity toward glucose in the presence of 10-folds uric acid and ascorbic acid. Moreover, this sensor showed good long-term stability for continuous glucose monitoring. The good selectivity, stability, and rapid response of this sensor suggests that it could have potential applications in long-term non-enzymatic blood glucose monitoring.
Highlights
Diabetes, caused by insulin deficiency or resistance, is a chronic disorder of glucose metabolism
The preparation of the Ni-Metal-organic frameworks (MOFs) glucose sensor was illustrated as Figure 1, following the sequence of the glass carbon electrode (GCE) polishing, NiMOFs synthesis, electrochemical activation, and glucose sensing
The synthesized Ni3(HITP)2 MOFs mixed with Nafion was dropped on the polished GCE
Summary
Diabetes, caused by insulin deficiency or resistance, is a chronic disorder of glucose metabolism. The instability, critical operating conditions, and limited lifetimes of enzymes hinder the application of this biosensor for continuous glucose monitoring (Zhang et al, 2013) To address these drawbacks, non-enzymatic electrochemical glucose biosensors, including noble metallic materials and their alloys, have been proposed and developed (Dolinska et al, 2014; Chang et al, 2015; Shen et al, 2015; Ye et al, 2015; Wei et al, 2018; Karimi-Maleh et al, 2020b). A mixture solution of 16 μL Ni-MOFs (1 mg mL−1) and 4 μL Nafion was added to the polished GCE surface and dried under room temperature. To active the Ni-MOFs, the cyclic voltammogram method was performed at the potential between 0.2 V to 0.6 V vs SCE at a scan rate of 50 mV s−1 for 100 cycles in a 0.1 M KOH solution until stable curves were obtained. The functional groups were tested by Fourier Transform Infrared Spectrometer (FTIR, Nicolet iS50)
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