The high luminescent polydopamine nanosphere-based ECL biosensor with steric effect for MUC1 detection

In this work, we have provided a sensitive electrochemiluminescence (ECL) sensor for MUC1 detection based on the steric effect. A new kind of high luminescent polydopamine nanospheres (HLPNs) was prepared as the ECL luminophore with potassium persulfate (K2S2O8) as co-reactant. Although polydopamine nanosphere have showed excellent biodegradability, biocompatibility, and low cytotoxicity, the low luminescence efficiency and poor optical-electrical activity limited the application performance of polydopamine nanosphere in the sensing system. In order to get high ECL performance, the oxidation with H2O2 was employed to reduce the conjugate degree with internal conversion efficiency of polydopamine nanosphere. In the next step, HLPNs and chitosan (CS) are fabricated on the surface of the glassy carbon electrode via the layer-by-layer self-assembly method. The multi-HLPNs layer-based sensor exhibited the strong ECL signal. When the aptamer on the electrode surface specifically recognized and captured target MUC1, straight-stranded DNA with MUC1 protein can fold on the electrode surface. Due to the space steric effect, co-reactant hardly generated the intermediate transition state on the electrode surface. As a result, less luminescent excited state of HLPNs were obtained. So, the ECL signal decreases linearly with increasing MUC1 concentration. The results show that the ECL sensor for MUC1 detection has high sensitivity, good specificity, and ideal feasibility, which provide potential clinical diagnosis application value.