Highly efficient synthesis of CeO2@g-C3N4 double-shelled hollow spheres for ultrasensitive self-enhanced electrochemiluminescence biosensors

In this work, CeO2@g-C3N4 double-shelled hollow spheres were skillfully synthesized as a novel type self-enhanced electrochemiluminescent (ECL) emitter by a highly efficient outside-in hard template method. Thanks to its great catalytic ability, CeO2 were served as a co-reaction accelerator for improving ECL performance of the hollow g-C3N4 spheres (HCNSs)/S2O82− system. In addition, the self-enhanced ECL emitter is designed as a complex containing a co-reaction accelerator and a luminophore to shorten the electron transfer path, which decreases the energy loss of the luminophore significantly. More importantly, the unique double-shelled hollow structure not only greatly decreases the inner filtering effect, but also maximizes the utilization efficiency of the ECL luminophores by increasing a CeO2 shell inside the HCNSs as co-reaction accelerator, effectively enhancing the ECL intensity. Under the optimal conditions, the designed ECL immunosensor showed excellent performance in the determination of CA19-9 with a linear range of 0.50 mU mL−1 –500.00 U mL−1 and a low detection limit of 0.039 mU mL−1. Importantly, the resulting biosensor has good stability, high sensitivity and reliable reproducibility, suggesting its potential application in clinical research.