An electrochemiluminescence sensor for the detection of prostate protein antigen based on the graphene quantum dots infilled TiO2 nanotube arrays

In this study, we prepared titanium dioxide nanotube arrays (TiO2 NTs) infilled with graphene quantum dots (GQDs) to create a hybrid structure (GQD/TiO2 NTs) and applied the GQD/TiO2 NTs as an efficient electrochemiluminescence (ECL) emitter in the detection of prostate protein antigen (PSA). The TiO2 NTs were infilled with the GQDs through an impregnation method. The GQD/TiO2 NP composite electrode showed a highly stable ECL, and, when K2S2O8 was used as a co -reactant, the ECL intensity increased 6-fold compared with that of a pure TiO2 NT electrode. Herein, to exploit the application of the GQD/TiO2 NT composite as an efficient ECL emitter for biosensing, a sandwich ECL immunoassay was developed using PSA as a model. CdTe nanoparticles (NPs) modified with Fe3O4 magnetic nanoparticles (CdTe/MNPs) served as quenchers for the ECL immunoassay. PSA could be detected using the ultrasensitive GQD/TiO2 NT platform. The decrease in the ECL intensity was linear with the log of the concentration of the PSA in the range from 1.0 fg mL(-1) to 10 pg mL(-1), with a lower detection limit of 1 fg mL(-1) (S/N = 3). The use of the ECL immunoassay for PSA detection were used to measure in clinical human serum samples of prostate cancer patients and controls with excellent correlation to referee chemiluminescence method.