Anodic electrochemiluminescence of graphitic-phase C₃N₄ nanosheets for sensitive biosensing.

This work observed the anodic electrochemiluminescence (ECL) of C₃N₄ nanosheets (CNNS) for the first time. The ECL emission was 40 times stronger than that from bulk g-C₃N₄ in the presence of triethylamine (Et₃N) as a coreactant due to large surface-to-volume ratio, which enhanced the sensitivity for biosensing. At pH 7.0, the CNNS modified electrode prepared with 0.75 mg mL(-1) CNNS in 0.025% chitosan solution possesses good stability and acceptable reproducibility in the presence of 30 mM Et₃N. The ECL mechanism of CNNS/Et₃N system was proposed to be emitted from the excited CNNS, which was produced during the reaction between the electro-oxidation products of CNNS and coreactant Et₃N. Based on the annihilation between the oxidation product of dopamine (DA(+)) and Et₃N radical, a quenching-based method was established for sensitive and specific detection of dopamine ranging from 1.0 nM to 100 nM with a detection limit of 96 pM by using the CNNS nanosheets as an ECL emitter. The proposed method showed excellent specificity, high sensitivity and low detection limit, and could be applied in analysis of real samples.