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Herein, we present the first report on label-free electrochemical sensing of D-Mannitol using MgAl2O4 Nanopowder (MAO) modified glassy carbon electrode (GCE) sensor for pico-molar detection of D-Mannitol in biological samples. The differential pulse voltammetry (DPV) technique is employed for the sensing of D-Mannitol over a wide linear range of detection ranging from 1 pM to 1.5 nM with a sensitivity of 6.47 nA/pM cm−2 and an ultra-low limit of detection (LOD, $3\sigma $ ) of 0.371 pM. The sensor shows an excellent selectivity towards D-Mannitol in the presence of interfering analytes such as glucose, sucrose, human serum albumin (HSA) and bovine serum albumin (BSA). Additionally, the sensor exhibits successful reproducibility with n = 5 devices and excellent stability. This enhanced performance of the MAO/GCE is attributed to the excellent electrocatalytic property of MAO thru Al2+/Al2+ redox couple facilitating the redox reaction of D-Mannitol and the presence of oxy functional groups which improves the adsorption process of D-Mannitol oxidase (mannose) onto the surface of MAO/GCE. The as-fabricated sensor could successfully determine D-Mannitol in the biological samples with excellent recovery percentages from ~98.2% to ~110.42% thus proving to be an excellent platform for developing low cost, high-performance bioanalytical sensing systems.

Herein, we report a facile synthesis of sodium niobiate (NaNbO3) perovskite nanomaterial using a solid-state reaction (SSR) via solvothermally grown niobium pentoxide (Nb2O5) nanopowder for the excellent sensitive detection of dopamine (DA) in simulated blood serum with high selectivity. The X-ray Diffraction (XRD) pattern and Raman spectrum revealed an orthorhombic phase formation for NaNbO3 and the presence of a NbO6 octahedra site, while the scanning electron microscopy (SEM) images confirmed berry-like cluster formations of NaNbO3. The NaNbO3 modified glassy carbon electrode (GCE) sensor showed an excellent selectivity against interfering species like Na+, Cl−, Ca2+, glucose, ascorbic acid (AA), anduric acid, a sensitivity of 99 nA nM−1 cm−2 in the wide dynamic range of 10 nM to 500 μM, and a limit of detection (LOD) of 6.8 nM towards DA sensing, making it suitable for detecting physiological levels of DA in human blood. The sensing mechanism for DA was ascribed to the presence of NbO6 octahedral sites in the NaNbO3 perovskite structure that interacted with the oxidase of DA (dopamine-o-quinone) through Nb5+/Nb4+ niobium states, resulting in an increase in the oxidation peak current. This sensor did not exhibit any kind of surface fouling effects due to the reduction mechanism and the Na+ ions stabilizing the perovskite structure. The as-fabricated NaNbO3/GCE sensor was further assessed for the detection of DA in simulated blood serum, which showed an excellent recovery percentage. This novel, binder-free, NaNbO3 perovskite-based modified electrode offers a promising platform for developing high performance, non-enzymatic electrochemical sensors for numerous bioanalytical applications.