A novel electrochemiluminescence immunosensor: BiOBr/Bi2WO6 heterojunction for ultrasensitive detection of CA19-9

Abstract

Bi2WO6, an environmentally friendly material with certain electrochemiluminescence (ECL) properties, has been used as a novel ECL luminescent material. In the present work, bismuth tungstate (Bi2WO6) was composited with bismuth bromide (BiOBr) to form a S-type heterojunction with a flower like morphology where the Bi2WO6 core was wrapped with BiOBr outer shell. The interface of the heterojunction is closely contacted, which can promote electron transfer, improve conduction and enhance ECL emission to a certain extent. The BiOBr/Bi2WO6 (BBW) heterojunction with K2S2O8 as a co-reactant demonstrates cathodic ECL emission at 550–800 nm in the potential range of −1.8–0 V. Cu2O@Ag with a special sea urchins morphology was introduced into the system to catalyze the reduction of S2O82− to generate more SO4•−, which further enhances the ECL emission. The ECL immunosensor constructed with the heterojunction for CA19–9 detection exhibits a robust linear relationship in the concentration range from 0.1 mU·mL−1 to 100 U·mL−1 and detection limit as low as 87.6 μU·mL−1. The immunosensor successfully detected CA19–9 in serum, showing great application potential in the clinical practice.