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

A robust real-time quantification method is essential to understand the physiological roles of endogenous H2O2 in biological systems. For this purpose, we described a binary transition-metal oxide (TMO)-based nanointerface, i.e., spinal zinc cobaltite/cobalt oxide ternary nanoarrays (ZnCo2O4/Co3O4) on a Cu foam (CF). The ZnCo2O4/Co3O4/CF facilitates H2O2 reduction at a minimized overpotential (−0.10 V vs Ag/AgCl). which is several millivolts away from the voltammetric regions of common biological and oxygen interferences, making the electrode highly selective in the presence of 5-fold excess concentrations of biological species. In the presence of ZnCo2O4, the electrocatalytic capability of Co3O4 has increased significantly by enlarging the electrochemical active area of the electrode (0.538 cm2). A substantial improvement in the stability (97.24%) and reproducibility (relative standard deviation = 3.14%) are attained because the direct growth of nanomaterials is generated on CF in close proximity with the electrode surface and strengthens the affinity. The modified electrode endows ultrasensitivity (detection limit = 1 nM) and quantifies the amount of H2O2 released from mammalian cells (8.7 × 10–14 mol). Binary TMOs hold promise in tailoring a reliable H2O2-detecting interface for real-time, in vivo applications.

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Alginate hydrogel fibers embedded with bone cells and diclofenac were coated with a layer of chitosan hydrogel and made into a porous scaffold by three-dimensional (3D) printing for drug release and bone regeneration. It was hypothesized that the chitosan coating could improve the scaffold's drug retention and release properties and biocompatibility. Macrophage cells were stimulated and cocultured with the scaffold. Tests were conducted to show how the chitosan coating affected the scaffold's drug release efficacy and how the release efficacy affected the cellular activities of stimulated macrophages and bone cells. The bone cells encapsulated in the coated scaffold demonstrated good viability after the acidic/basic coating process. The coating improved the retention and release efficacy of diclofenac and hence significantly inhibited interleukin-6 and tumor necrosis factor-α secretion from macrophages (p < 0.05). The bone cells in the coated sample mineralized more extensively than the control (p < 0.01). They also more actively expressed genes that produce proteins for extracellular matrix remodeling, MMP13, and interacting with the mineral matrix, OPN (both p < 0.01). It is believed that on days 7 and 10, when diclofenac was depleted and the concentrations of inflammatory compounds surged, the coating effectively blocked the harmful compounds and protected the bone cells within the fibers. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1511-1521, 2018.