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[Display omitted] • Manipulating Co 3 O 4 deposition for best electrocatalytic performance in dopamine sensing. • Doping on super-aligned electrospun carbon nanofiber scaffolds for site activity. • Rapid responses of dopamine reaction at the electrode surface. • Highly sensitive to secreted dopamine secreted from living cells. • Superior stability and reproducibility of as-prepared electrode sensors. A demand exists for the development of miniaturized biosensors with high sensitivity and a wide dynamic range for rapid detecting dopamine (DA) levels. In this work, an electrochemical sensor is created by decorating closely packed cobalt oxide (Co 3 O 4) nanograins on nitrogen-doped electrospun carbon nanofibers (NECNFs) via a facile electrodeposition method. The carbon nanofiber matrix provides both a scaffold with ultrahigh surface area for homogeneous dispersion of cobalt oxide nanostructures and facilitates the electrochemical conductivity for the hybrid electrode. The sensing principle is based on the redox reaction between DA and DA quinone that generates electrical signal, which is detectable via differential pulse voltammetry (DPV) and chronoamperometry (CA). Owing to a high electroactive surface area and facilitating electron transfer between electrode surface and the target molecule, the electrical sensing platform exhibits superior sensitivity and selectivity toward DA, with an excellent limit of detection (9 nM) over a wide range of concentrations (0.01 to 100 µM). Moreover, based on its excellent sensing properties and biocompatibility, the sensor has been used for the real-time monitoring exogeneous DA released from pheochromocytoma (PC12) cells. This work demonstrates promise of a novel sensor technology that may render rapid point-of-care testing of DA towards early clinical diagnosis. [ABSTRACT FROM AUTHOR]

Abstract The stability and magnetic susceptibility of galvinoxyl radicals are believed to underpin the behaviour of ferromagnetic organic layers. However, the magnetic response associated with electron transfer from galvinoxyl radicals remains little understood. Here, new findings on magnetically-enhanced electron transfer (MEET) from immobilized galvinoxyl radicals are reported in an electrochemical study using galvinoxyl–gold electrodes. The electron transfer rate constant increases by about 78% in the presence of an external magnetic field of 1.32 mT compared to the electron transfer rate in the absence of a magnetic field. The MEET of organic radical layers on a solid electrode may also open up new avenues for the development of novel ferromagnetic nanostructures and devices. Graphical abstract Unlabelled Image Highlights • A study of the effect of a magnetic field on the electron transfer rate of a ferromagnetic material. • Cyclic voltammetry measurements were conducted using a gold electrode coated with galvinoxyl radicals. • An extended Marcus model was used to calculate the electron transfer rate constant. • A new phenomenon of magnetically enhanced electron transfer was reported. [ABSTRACT FROM AUTHOR]