Enhanced electrochemical reduction of hydrogen peroxide on silver paste electrodes modified with surfactant and salt

The Development of CMOS Amperometric Sensing Chip with a Novel 3-Dimensional TiN Nano-Electrode Array

An electrochemical sensing chip with an 8 × 8 array of titanium nitride three-dimensional nano-electrodes (TiN 3D-NEA) was designed and fabricated via a standard integrated complementary metal oxide semiconductor process. Each nano-electrode in 3D-NEA exhibited a pole-like structure with a radius of 100 nm and a height of 35 nm. The numeric simulation showed that the nano-electrode with a radius of around 100 nm exhibited a more uniformly distributed electric field and a much higher electric field magnitude compared to that of the microelectrode. Cyclic voltammetry study with Ru(NH₃)₆³⁺ also revealed that the TiN 3D-NEA exhibited a much higher current density than that obtained from the microelectrode by two orders of magnitude. Further studies showed that the electrocatalytical reduction of hydrogen peroxide (H₂O₂) could occur on a TiN 3D-NEA-based sensing chip with a high sensitivity of 667.2 mA⋅mM⁻¹⋅cm⁻². The linear detection range for H₂O₂ was between 0.1 μM and 5 mM with a lowest detection limit of 0.1 μM. These results indicated that the fabricated TiN 3D-NEA exhibited high catalytic activity and sensitivity to H₂O₂ and could be a promising sensor for H₂O₂ measurement.

Electrochemical detection of extracellular hydrogen peroxide in Arabidopsis thaliana: a real-time marker of oxidative stress

An electrochemical approach to directly measure the dynamic process of H2 O2 release from cultures of Arabidopsis thaliana cells is reported. This approach is based on H2 O2 oxidation on a Pt electrode in conjunction with continuous measurement of sample pH. For [H2 O2 ] <1 mm, calibration plots were linear and the amperometric response of the electrode was maximum at pH 6. At higher concentrations ([H2 O2 ] >1 mm), the amperometric response can be described by Michaelian-type kinetics and a mathematical expression relating current intensity and pH was obtained to quantitatively determine H2 O2 concentration. At pH 5.5, the detection limit of the sensor was 3.1 µm (S/N = 3), with a response sensitivity of 0.16 Am(-1 ) cm(-2) and reproducibility was within 6.1% in the range 1-5 × 10(-3 ) m (n = 5). Cell suspensions under normal physiological conditions had a pH between 5.5-5.7 and H2 O2 concentrations in the range 7.0-20.5 µm (n = 5). The addition of exogenous H2 O2 , as well as other potential stress stimuli, was made to the cells and the change in H2 O2 concentration was monitored. This real-time quantitative H2 O2 analysis is a potential marker for the evaluation of oxidative stress in plant cell cultures.