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• A smartphone-interfaced flow injection sensing system was developed. • An electrode was modified with Pd-PANI/Carbon microspheres@carbon nanotubes. • Sensitive determination of glucose was achieved in real human serum samples. Integrating a flow injection system with an electrochemical sensor controlled by a smartphone enables rapid, precise real-time monitoring and reduces analyte consumption, contamination and costs. An enzyme-free electrochemical sensor is presented for the monitoring of glucose, an important indicator of diabetes. The sensor integrates a smartphone and a flow injection amperometric system. The flow cell is fabricated from acrylic plastic and includes an electrochemical three-electrode cell that comprises a working electrode modified with a catalyst of palladium-polyaniline/carbon microspheres@carbon nanotubes (Pd-PANI/CM@CNTs/E) for the detection of glucose oxidation. In the optimal condition, the proposed system produced good analytical performances. The sensor determined glucose linearly in a range from 0.020 to 100 mM, with a sensitivity of 51.51 μA mM−1 cm−2, and a detection limit (LOD) of 0.0071 mM. The developed system also exhibited good repeatability, reproducibility, operational stability, and anti-interference properties, and accurately determined glucose levels in real human serum samples. This sensing platform provides an alternative tool for the development of a continuous glucose monitor system for clinical applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Regular monitoring of blood sugar levels is essential for diabetics, both for adjusting medication or insulin doses and for preventing complications like blindness, nerve damage, heart disease, and kidney failure. This paper presents a novel smartphone-based electrochemical-colorimetric dual-mode detecting system for detecting glucose at low concentrations. This system utilizes a smartphone as a mobile terminal to control the electrochemical circuit board and enable data analysis. The circuit board integrates cyclic voltammetry and differential pulse voltammetry, providing a low-cost and palm-sized solution for glucose detection. Additionally, digital image colorimetry is employed to enable efficient and accurate colorimetric detection. The use of glucose oxidase and horseradish peroxidase (GOx/HRP) in combination with 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) ABTS substrates facilitates glucose dual-mode quantitative analysis in a-coreaction system. The electrochemical and colorimetric methods exhibit limits of detection of 0.467 µM and 10 µM, respectively. This system shows a point-of-care testing (POCT) potential for reliable and convenient monitoring of blood glucose levels, particularly for individuals with diabetes. [ABSTRACT FROM AUTHOR]

• Electrodeposition of nanoplatelets like structure of samarium oxides. • High charge transfer rate constant and roughness factor. • Hydrogen peroxide reduction from −0.10 V (vs. Ag/AgCl). • Physical adsorption of glucose oxidase. • Glucose determination in serum samples. A nanostructured samarium oxide electrode was constructed by electrodeposition onto the surface of a gold electrode on SiO 2 /Si wafer. The samarium oxides electrode's surface morphology was investigated by scanning electron microcopy showing a quasi-monodispersed nanoplatelets like structure. X-rays diffraction analysis demonstrated a mixture of monoclinic and hexagonal phases while the X-rays photoelectron spectroscopy indicated the co-existence of both Sm2+ and Sm3+ species in a 1:3 proportion. Cyclic voltammetry and electrochemical impedance spectroscopy were used to investigate the charge transfer processes at the surface of the samarium oxide electrode in the absence and in the presence of redox probes. A roughness factor of 2.5 was determined from the samarium oxide electrode while the charge transfer constant was almost double when compared to the planar gold electrode. Then, the samarium oxide electrode was used for the H 2 O 2 detection by fixed potential amperometry at -0.20 V (vs. Ag/AgCl) with a linear region between 0.01 and 1.00 mM, a sensitivity of 153 µA cm−2 mM−1 and a LoD = 2.70 µM. Glucose oxidase was used as a model enzyme in order to test the capacity of the samarium oxides electrode for biosensing. The enzyme was immobilized by physical adsorption and the optimum conditions for glucose analysis investigated. The biosensor showed a linear range for glucose detection between 0.10 and 1.20 mM with a sensitivity of 8.40 µA cm−2 mM−1 and a LoD = 8.00 µM. Selectivity was tested toward common interfering species, and the results revealed the lack of biosensor response. The glucose biosensor on samarium oxides was tested for glucose detection in serum samples with a recovery factor of 90%, and the result validated with a commercial glucometer. [Display omitted] [ABSTRACT FROM AUTHOR]

In this work, we report a high-performance graphene flexible paper electrode composed of core-shell Gold@Prussian blue nanoparticles (Au@PB NPs) for real-time monitoring of living cell and biosensor platform. Core-shell Au@PB NPs with high stability, low cost, excellent biocompatibility and electrochemical activity was prepared. At the same time, combined with the robust mechanical properties of reduced graphene oxide (rGO) paper, an independent flexible graphene paper electrode was prepared and broadly characterized. Because of the unique structural properties and the combinational advantages of different components in the Au@PB NPs-rGO composite, the resultant nanohybrid paper electrode exhibits good electrochemical sensing performance toward hydrogen peroxide (H 2 O 2) and it also displays a very short response time (1 s) in the tracking of H 2 O 2 secretion by living HepG2 cells. Meanwhile, the as-prepared Au@PB NPs-rGO paper electrode can be further used as an enzyme-based biosensor. In this regard, glucose oxidase (GODx) used as an example for glucose detection and analysis, which proves its excellent performance as an enzyme sensing platform. The excellent properties of the kind of nanocomposites are expected to be further used in the field of flexible devices and Point-of-Care (POC). [ABSTRACT FROM AUTHOR]