ZnCo₂O₄ Nanoflowers Grown on Co₃O₄ Nanowire-Decorated Cu Foams for in Situ Profiling of H₂O₂ in Live Cells and Biological Media

Abstract

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.

Nonspherical Metal‐Based Nanoarchitectures: Synthesis and Impact of Size, Shape, and Composition on Their Biological Activity

“…The hydrothermal method has been used to synthesize metal nanowires such as ZnO, [ 111 ] CoS, [ 112 ] MnO 2 , [ 36 ] Pd, [ 113 ] and Co 3 O 4. [ 114 ] The mechanism for synthesis of ZnO nanowires is similar to what was described earlier for nanorods in Section 2.1.3. The major difference is the use of a capping agent such as polyethyleneimine to prevent lateral growth of the nascent nanostructure.…”

Sensors Based Upon Nanowires, Nanotubes, and Nanoribbons: 2016–2020

“…Modification of another metal oxide nanostructure on the surface of a metal oxide NW is also an effective way to improve its catalytic performance. The electrocatalytic capability of Co 3 O 4 NWs is reported to increase significantly when hybridized with ZnCo 2 O 4 nanoflowers . Core–shell IrO 2 @NiO NWs also exhibited superior electrocatalytic activity over pure NiO nanoflowers and IrO 2 NWs, which is attributed to the metal-like conductivity (resistance of ∼50 μΩ cm –2 in bulk) of IrO 2 .…”

“…The development of electrochemical biosensors for environmental monitoring, health care, and clinical diagnostics has recently become a hot topic due to their advantageous low cost, fast response, easy miniaturization, and suitability for direct analyses. ,− It is well-known that biosensor electrochemical performances can be modified by different compositions and morphologies of electrode nanomaterials . Among all the materials to modify electrodes, 1D nanostructured metal oxides like Cu 2 O, MnO 2 , Fe 2 O 3 , Fe 3 O 4 , ZnO, TiO 2 , and Co 2 O 3 have attracted much interest for electrochemical applications in sensors, supercapacitors, and batteries due to the controlled structure for distinct anisotropy, electron transfer, quantum size effect, and large surface area-to-volume ratio. , …”

“…The first role is to immobilize biomolecules in the fabrication of biosensors like immunosensors, enzyme sensors, and DNA sensors, which act as the electron transfer medium. , The reaction of a small number of biomolecules produces a large electrical signal, which is easily measurable with electrochemical instruments due to the nanowire’s high surface area-to-volume ratio. The second role is to act as electrocatalysts when catalyzing target molecules, such as glucose, dopamine, H 2 O 2 , ascorbic acid, dihydroxybenzene, and l -cysteine. ,,,,− …”

“…Researchers are looking for new metal oxide nanomaterials, making new nanostructures or modifying noble metals on the surface of semiconductors to improve their conductivity and catalytic efficiency. Efforts in this front are motivated by decreasing the working potential, reducing the influence of interfering substances, and improving the performance of the sensor. ,,, …”