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Highlights • Non-enzymatic electrochemical glucose sensor based on bronze which was installed on a smart toothbrush. • Good selectivity and high sensitivity towards glucose oxidation in the presence of interfering species. • This sensor can be regenerated simply by mechanically polishing for long-term uses. Abstract Bronze is one of copper alloy materials that have been widely used not only in the Bronze Age, but also nowadays because they are hard, easy to cast and resistant against corrosion. For bronze, tin is commonly used as the major non-copper ingredient of bronze because of many highly desirable characteristics including the fact that metallic tin is not toxic. We find that the tin bronze is a suitable electrode material for non-enzymatic electrochemical glucose sensing in saliva. For electrocatalytic oxidation of glucose on the bronze electrode, a negative potential is applied for proton reduction which creates a temporary alkaline condition. The sensor has a linear range from 0 to 320 μM with the regression equation: i = 11 + 0.015 C (i is the current in μA and C is the concentration in μM) with a correlation coefficient of 0.994. The sensitivity is found to be 480 μA mM−1 cm-2, and the detection limit is 6.6 μM with a signal-to-noise ratio of 3. The electrode is found to be highly selective towards glucose oxidation in the presence of interfering species such as ascorbic acid and uric acid. The electrochemical senor is integrated into a smart toothbrush for monitoring of saliva glucose, which is potentially useful for non-invasive screening of diabetes. Compared with other electrochemical glucose sensors, a naked bronze electrode is used as the working electrode to ensure the robustness of the sensor. No additional reagent is involved for the electrochemical determination of saliva glucose and the electrode can be regenerated simply by mechanically polishing for long-term uses. [ABSTRACT FROM AUTHOR]

Cu nanoparticle/graphene oxide/single walled carbon nanotube (CuNP/GO/SWCNT) composites were prepared by a facile electrodeposition method and used for constructing nonenzymatic glucose sensor. Scanning electron microscopy (SEM) and Raman spectroscopy were employed to characterize the morphology and structures of the samples. The electrocatalytic performance of CuNP/GO/SWCNT composites towards glucose oxidation was studied by cyclic voltammetry (CV) and current–time measurements. Electrochemical results indicated that CuNP/GO/SWCNT electrode exhibited a higher electrocatalytic activity towards the oxidation of glucose than CuNP, CuNP/GO and CuNP/SWCNT electrodes. This was because the GO/SWCNT composite as substrate material not only possessed excellent conductivity, but also provided large surface area for the high loading of the CuNPs. Meanwhile, the good dispersibility, independent and multi-layer structure of CuNP, could enhance the charge-transport properties, and afford more active sites for the catalytic oxidation of glucose. Under the optimized conditions, the sensor showed a high sensitivity of up to 930.07 μA mM − 1 cm − 2 , with a wide linear range of 1 μM to 4.538 mM and a low detection limit of 0.34 μM (S/N = 3). It also exhibited excellent stability, reproducibility, selectivity, and reliable measurement in real human blood samples. All of these excellent properties made the CuNP/GO/SWCNT composite material promising for the development of effective nonenzymatic glucose sensors. [ABSTRACT FROM AUTHOR]

The intrinsically fragile nature and leakage of the enzymes is a major obstacle for the commercial sensor of a continuous glucose monitoring system. Herein, a dual confinement effect is developed in a three dimensional (3D) nanocage-based zeolite imidazole framework (NC-ZIF), during which the high-loading enzymes can be well encapsulated with unusual bioactivity and stability. The shell of NC-ZIF sets the first confinement to prevent enzymes leakage, and the interior nanocage of NC-ZIF provides second confinement to immobilize enzymes and offers a spacious environment to maintain their conformational freedom. Moreover, the mesoporosity of the formed NC-ZIF can be precisely controlled, which can effectively enhance the mass transport. The resulted GOx/Hemin@NC-ZIF multi-enzymes system could not only realize rapid detection of glucose by colorimetric and electrochemical sensors with high catalytic cascade activity (with an 8.3-fold and 16-fold enhancements in comparison with free enzymes in solution, respectively), but also exhibit long-term stability, excellent selectivity and reusability. More importantly, the based wearable sweatband sensor measurement results showed a high correlation (>0.84, P < 0.001) with the levels measured by commercial glucometer. The reported dual confinement strategy opens up a window to immobilize enzymes with enhanced catalytic efficiency and stability for clinical-grade noninvasive continuous glucose sensor. [Display omitted] • A dual-confinement strategy that can doubly confine high-loading enzymes within NC-ZIF with unusual bioactivity and stability. • The mesoporosity of NC-ZIF can be precisely regulated to optimize the performance of packaged enzymes by adjusting the etching times. • The optimized GOx/Hemin@NC-ZIF catalyst could realize high sensitivity detection of glucose by colorimetric and electrochemical sensors. • The based wearable sweatband sensor measurement results show a high correlation (>0.84, P < 0.001) with the levels measured by commercial glucometer. [ABSTRACT FROM AUTHOR]