Determination of cytochrome c based on its enhancing effect on the electrogenerated chemiluminescence of carbon quantum dots

Carbon dots (C-dots) display strong cathodic electrogenerated chemiluminescence (ECL) in neutral aqueous solution in the presence of potassium persulfate. ECL intensities strongly depend on the method of synthesis of C-dots. The reactions between the electrochemically reduced intermediates of C-dots and potassium persulfate generate a strong ECL signal. Spectral and electrochemical studies revealed that cytochrome c reacts with potassium persulfate before its electrochemical reduction to generate the strong oxidant radical SO 4 •- which reacts with C-dots to give an enhanced ECL signal. This finding was exploited to design a sensitive ECL assay for cytochrome c. The effects of the amount of C-dots, the pH value, and the persulfate concentration were optimized. Under the optimal conditions, the ECL signals (generated at −1.4 V) increase linearly with the concentration of cytochrome c in the range from 1.0 nM to 10 μM, with a detection limit of 0.2 nM. The modified electrode exhibits high sensitivity and good selectivity. Carbon dots display strong cathodic electrogenerated chemiluminescence (ECL) in neutral condition with potassium persulfate as coreactant. Cytochrome c strongly enhances the ECL signal, and can be sensitively detected by exploiting this effect.