Hydrogen peroxide (H 2 O 2 ) is an eminent biomarker in pathogenesis; a selective, highly sensitive real-time detection of H 2 O 2 released from live cells has drawn a significant research interest in bioanalytical chemistry. Binary transition-metal oxides (BTMOs) displayed a recognizable benefit in enhancing the sensitivity of H 2 O 2 detection; although the reported BTMObased H 2 O 2 sensor's detection limit is still insufficient, it is not appropriate for in situ profiling of trace amounts of cellular H 2 O 2 . In this paper, we describe an efficient, reliable electrochemical biosensor based on Mn 2 CuO 4 (MCO) microspheres to assay cellular H 2 O 2 . The Mn 2 CuO 4 microspheres were prepared through a superficial solvothermal method. It is obvious from impedance studies, introduction of manganese into copper oxide lattice significantly improved the ionic conductivity, which is beneficial for the electrochemical sensing process. Thanks to the distinct microsphere structure and excellent synergy, MCO-modified electrode exhibited excellent nonenzymatic electrochemical behavior toward H 2 O 2 sensing. The MCO-modified electrode delivered a broad working range (36 nM to 9.3 mM) and an appreciable detection limit (13 nM), with high selectivity toward H 2 O 2 . To prove its practicality, the developed sensor was applied in the detection of cellular H 2 O 2 released by RAW 264.7 cells in presence of CHAPS. These results label the possible appliance of the sensor in clinical analysis and pathophysiology. Thus, BTMOs are evolving as a promising candidate in designing catalytic matrices for biosensor applications. KEYWORDS: reactive oxygen species (ROS), H 2 O 2 , manganese copper oxide, electrocatalysis, electrochemical sensor

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Herein, a hierarchical structure of flower-like NiCo layered double hydroxides (NiCo LDH) microspheres composed of three-dimensional (3D) ultrathin nanosheets was successfully synthesized via a facile hydrothermal approach. The formation of NiCo LDH was confirmed by various physicochemical studies, and the NiCo LDH-modified glassy carbon electrode was used as an efficient dual-functional electrocatalyst for non-enzymatic glucose and hydrogen peroxide (H2O2) biosensor. The host matrix of hydrotalcite NiCo LDH exhibits the enhanced electrocatalytic sensing performances with a quick response time (<3 s), wide linear range (50 nM–18.95 mM and 20 nM–11.5 mM) and lowest detection limits (S/N = 3) (10.6 and 4.4 nM) toward glucose and H2O2, and also it exhibits good stability, selectivity, and reproducibility. In addition, this biosensor was successfully utilized to the real-time detection of endogenous H2O2 produced from live cells and glucose in various biological fluids, and demonstrates that the as synthesized NiCo LDH may provide a successful pathway for physiological and clinical pathological diagnosis.

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Present strategy introduce the sonochemical synthesis of molybdenum oxide (MoO) microspheres anchored graphitic carbon nitride (g-CN) ultrathin sheets as a novel electrocatalyst for the detection of Furazolidone (FU). TEM results revealed that MoO are microspheres with an average size of 2 µM and the g-CN seems like ultrathin sheets. Owing to their peculiar morphological structure, g-CN/MoO composite modified electrode provided an enriched electroactive surface area (0.3788 cm) and higher heterogeneous electron transfer kinetics (K° = 4.91×10 cm s) than the other controlled electrodes. It is obviously observed from the voltammetric studies that the proposed sensor based on g-CN/MoO composite can significantly improve the electrocatalytic efficiency towards the sensing of FU. Due to the excellent synergic effect of g-CN/MoO composite, can detect the ultra-level FU with a limit of detection of 1.4 nM and a broad dynamic range of 0.01-228 µM, which surpassed the many previously reported FU sensors. Hence, the proposed sensor was successfully applied to sensing the FU in human blood serum, urine and pharmaceutical samples, gained an agreeable recoveries.

An efficient detection of lethal environment pollutants via the simple and sensitive analytical method has drawn the central importance. In this work, the cotton flower like structured gold nanoparticle decorated functionalized carbon black/polytyramine (f-CB-PTy-Au) ternary nanocomposite was synthesized via the sonochemical synthesis method. The strong covalent interaction between the hydroxyl and amine group from the f-CB and PTy enhances the polymerization. Besides, the flower shaped gold nanoparticles (AuNPs) decorated on the surface of the f-CB-PTy via the non-covalent interaction. The structural properties of the f-CB-PTy-Au nanocomposite were probed by various spectrophotometric techniques. Then, the as-prepared nanocomposite was used to fabricate the electrochemical sensor for the amperometric determination of hazardous pollutant hydroquinone (HQ). Outstandingly, the proposed sensor demonstrated the wide linear response ranges from 0.006 μM to 2400 μM and the lowest LOD value around 0.1 nM was achieved. The favorable sensitivity of the proposed sensor was calculated about 3.423 μA μM −1 cm −2 . Furthermore, the practical applicability was investigated in different water samples such as tap water, waste water and river water.

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