Glycerate-assisted CoMn-sulfide with microsphere architecture confined by nanoparticles as an efficient enzyme-free sensor for amperometric measurement of glucose in serum, saliva and beverage samples

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The preparation of binary metal chalcogenides with ideal architectures can effectively enhance the electrocatalytic properties of these materials, as promising glucose sensors. Herein, CoMn-S spheres were synthesized using CoMn-glycerate as the precursor, followed by a sulfidation reaction. First, glycerate spheres were prepared by solvothermal treatment of Co and Mn ions in isopropanol solvent mixed with glycerol. Then, CoMn-glycerate was solvothermally sulfidized using an ion-exchange process to prepare glycerate-assisted CoMn-S spheres with many nanoparticles on their surface which provide abundant electrocatalyst sites. The sensing outcomes revealed that glycerate-assisted CoMn-S spheres have impressive electroanalytical performance with high sensitivities of 5148 and 1928 μA mM−1 cm−2 in broad measuring ranges of 0.001–0.63 mM and 0.63–2.53 mM, quick response to glucose oxidation (2 s), and a low detection limit of (0.88 μM). Furthermore, the sensor has been successfully employed to measure glucose in human serum, saliva, and beverage samples such as fruit juice, milk, and soft drinks with satisfactory recoveries. The high electrocatalytic activity of the CoMn-S sphere sensor results from the synergy between the components and nanoparticle-assembled microspheres, which creates a high surface area, shortens the charge transfer routes, and improves the electro-conductivity. The performance characteristics of the glycerate-assisted CoMn-S spheres were compared with CoMn-hydroxide needles and CoMn-S sheets. The glycerate-derived design provides an efficient and effective strategy to construct the enzyme-free platforms with high assay capability.