Nitrogen-Doped 4H Silicon Carbide Single-Crystal Electrode for Selective Electrochemical Sensing of Dopamine

In this work, we designed, fabricated, and characterized the first nitrogen (N)-doped single-crystalline 4H silicon carbide (4H-SiC) electrode for sensing the neurotransmitter dopamine. This N-doped 4H-SiC electrode showed good selectivity for redox reactions of dopamine in comparison with uric acid (UA), ascorbic acid (AA), and common cationic ([Ru(NH₃)₆]³⁺), anionic ([Fe(CN)₆]^3-), and organic (methylene blue) redox molecules. The mechanisms of this unique selectivity are rationalized by the unique negative Si valency and adsorption properties of the analytes on the N-doped 4H-SiC surface. Quantitative electrochemical detection of dopamine by the 4H-SiC electrode was achieved in the linear range from 50 nM to 10 μM with a detection limit of 0.05 μM and a sensitivity of 3.2 nA.μM^-1 in a pH = 7.4 phosphate buffer solution. In addition, the N-doped 4H-SiC electrode demonstrated excellent electrochemical stability. This work forms the foundation for developing 4H-SiC as the next-generation robust and biocompatible neurointerface material for a broad range of applications such as the in vivo sensing of neurotransmitters.