An ultrasensitive electrochemical sensor based on cotton carbon fiber composites for the determination of superoxide anion release from cells.

A sensor is described for determination of superoxide anion (O2˙-). The electrode consists of nitrogen-doped cotton carbon fiber (NCFs) modified with silver nanoparticles (AgNPs) which have excellent catalytic capability. The resulting sensor, best operated at working potentials around -0.5 V (vs. SCE), can detect O2˙- over an extraordinarily wide range that covers 10 orders of magnitude, and the detection limit is 2.32 ± 0.07 fM. The electrode enables the release of O2˙- from living cells under normal or under oxidative stress conditions to be determined. The ability to scavenge the superoxide anions of antioxidants was also investigated. In the authors' perception, the method represents a viable tool for studying diseases related to oxidative stress. Graphical abstract Schematic presentation of the construction of an electrochemical sensor based on Nitrogen-doped cotton carbon fiber and silver nanoparticles. It can be used for the direct detection of superoxide anions released from Glioma cells (U87) under normal or under oxidative stress conditions.

A sensitively non-enzymatic amperometric sensor and its application in living cell superoxide anion radical detection.

Here, we report a nanocomposite composed of silver nanoparticles and multi-walled carbon nanotubes (AgNPs/MWNTs) utilized as an efficient electrode material for sensitive detection superoxide anion (O2•-). The procedure to synthesize AgNPs/MWNTs nanocomposites was green and facile. In the presence of functionalized multi-wall carbon nanotubes (MWNTs), silver nanoparticles (AgNPs) were in situ generated by chemical reduction of silver nitrate with glucose as a reducing and stabilizing agent to give the desired AgNPs/MWNTs nanocomposites. The nanocomposites can be easily used for the construction of an electrochemical sensor on glassy carbon electrode (GCE). The characterization of sensor and experimental parameters affecting its activity were investigated employing scanning electron microscopy (SEM), energy-dispersive X-ray spectrometer (EDS), X-ray diffraction (XRD), and cyclic voltammetry (CV). The resulted sensor exhibited favorable electrochemical performance for O2•- sensing with a low detection limit of 0.1192 nM and wide linear range of 6 orders of magnitude, which guarantees the capacity of sensitive and credible detection of O2•- released from living cells. Notably, a simulation experiment indicated the capacity to resist oxidative stress is limited in biological milieu. Thus this work has great potential for further applications in biological researches.