Hierarchical C-N doped NiO with dual-head echinop flowers for ultrasensitive monitoring of epinephrine in human blood serum

The authors describe nanoelectrodes based on the use of hierarchical carbon-nitrogen nanospheres and dual-head nickel oxide echinop flowers (CN@HDN) placed on indium tin oxide (ITO) electrodes. The modified electrodes enable sensitive detection of catecholamine neurotransmitters, specifically of epinephrine (EPI) in human serum samples. The modified electrodes possess many active sites along the {111} crystal plane and large contact surfaces. This enables a rapid EPI diffusion within a highly active transport surface. The geometrical and morphological structures of the NiO decorated with CN-nanospheres render superior electrocatalytic behavior at a relatively low working voltage of 0.12 V (vs. Ag/AgCl) which makes the sensor relatively specific. The use of CN also increases the electron transfer rate and facilitates mass transfer between electrolyte (EPI sample) and catalytically active sites. The electrode is sensitive, selective and works at near-physiological pH values. It has a detection limit as low as 4 nM of EPI.