A double reaction system induced electrochemiluminescence enhancement based on SnS2 QDs@MIL-101 for ultrasensitive detection of CA242

At present, the development of electrochemiluminescence (ECL) immunosensor with excellent performance is still the research focus of immunoassay and detection. Herein, SnS2 quantum dots (SnS2 QDs) and metal-organic framework (MIL-101 (Cr)) are effectively combined to achieve synergistic signal amplification based on K2S2O8 co-reactant, thereby constructing SnS2 QDs/SO4•- and SO4•-/O2 ECL double reaction luminous systems. SnS2 QDs and singlet oxygen (1(O2)2*) produced from the system as light-emitting devices jointly enhance the ECL response and significantly improve the sensitivity of the ECL immunosensor. Dissolved oxygen and SnS2 QDs respectively generate HOO• and SnS2 QDs•- under negative potential, and react with transient SO4•- to emit strong light respectively, so as to jointly enhance the ECL response. MIL-101 catalyzes the oxygen cathode reduction reaction to promote the conversion of dissolved oxygen into HOO•, which greatly improves the ECL response of 1(O2)2*. CuS with spherical nanoflower-like form as a co-reaction promoter of K2S2O8 generate more SO4•- active substances, which further enhance the ECL response of the immunosensor. The constructed ECL immunosensor has the advantages of low detection limit, high sensitivity and better stability. Under the optimal conditions, the detection range is 0.1 mU/mL∼100 U/mL, and the detection limit is 0.015 mU/mL. The results show that the constructed ECL immunosensor can detect human CA242 samples and have a broad application prospect in biological analysis and early diagnosis of diseases.