An electrochemiluminescence biosensor for dopamine based on the recognition of fullerene-derivative and the quenching of cuprous oxide nanocrystals

In this work, L-cysteine (L-Cys) and 3-aminophenylboronic acid (APBA) consecutively reacts with fullerene (C-60) to obtain a new fullerene-derivative (L-Cys-C-60-APBA) with better biocompatibility, conductivity and hydrophilicity. L-Cys-functionalized C-60 can act as an excellent co-reactant to the electrochemiluminescence (ECL) of peroxydisulfate-oxygen (S2O82--O-2) system and greatly amplify the luminescence signal. APBA-functionalized C-60 has specific recognition to dopamine (DA) with diol structure. Therefore, a sensitive sensing interface for DA can be constructed based on the obtained L-Cys-C-60-APBA and the ECL of S2O82--O-2 system. Furthermore, cuprous oxide (Cu2O) nanocrystals, prepared with a modified reductive solution chemistry route, can promote the oxygen reduction reaction commendably. Thus, Cu2O modified on the electrode has a strong quenching effect to the ECL of S2O82--O-2 system. And the quenching effect is positively correlated with concentrations of DA, by which DA can be selectively and sensitively detected. The linear range is from 0.01 mu M to 40 mu M with a relatively low detection limit of 0.003 mu M (S/N = 3).