A dual-emitting immunosensor based on manganese dioxide nanoflowers and zinc sulfide quantum dots with enhanced electrochemiluminescence performance for the ultrasensitive detection of procalcitonin

A dual-emitting electrochemiluminescence (ECL) immunosensor based on manganese dioxide nanoflowers (MnO2NFs) and zinc sulfide quantum dots (ZnSQDs) was constructed for the first time to sensitively detect procalcitonin (PCT) in human serum. rGO@Ag functioned not only to adsorb primary antibodies (Ab1) but also to improve the electrical conductivity of the immunosensor. The MnO2NFs and ZnSQDs in the nanocomposite, synergistically with silver nanoparticles, simultaneously functioned as cathodic ECL emitters to enhance the detection sensitivity of PCT by shortening the electron-transfer path, thereby reducing energy loss. Under the optimized experimental conditions, the ECL immunosensor was capable of quantitatively detecting PCT in the linear range of 0.1 pg mL−1 to 100 ng mL−1 and over the scanning potential range of −2.0–0 V, with a detection limit of 0.033 pg mL−1. Furthermore, the ECL immunosensor demonstrated high specificity for PCT in the presence of other competing antigens, excellent stability over 10 cycles, and excellent reproducibility, corroborating its potential for measuring PCT concentrations in clinical samples.