An ultrasensitive ratiometric electrochemiluminescence immunosensor combining photothermal amplification for ovarian cancer marker detection.

Signal amplification strategies play important functions in the development of highly sensitive electrochemiluminescence (ECL) immunosensing system. Herein, a photothermal enhanced ratiometric ECL immunosensor was proposed for the detection of human epididymis protein 4 (HE4), an ovarian cancer biomarker. Mesoporous SiO2 (ms-SiO2) and carbon nanohorns (CNHs) was served as carrier of ECL emitter carbon nitride nanosheet (g-C3N4) and anodic ECL emitter polymer dots (Pdots), respectively. The large specific area of ms-SiO2 and CNHs improved the loading capacity of g-C3N4 and Pdots, enhancing ECL signals. Furthermore, CNHs was innovatively utilized as thermal convert unit to increase the electrode surface temperature, which benefited from its extraordinary photothermal property at 808 nm that can convert laser energy into heat for elevating the temperature, further amplified ECL signal. The delicately designed ECL immunosensor exhibited excellent sensitivity to HE4 detection with wide linear range from 1.0 × 10-5 to 10 ng/mL and low detection limit of 3.3 × 10-6 ng/mL. This work not only provided an effective way to develop highly sensitive ECL immunosensor but could attract more attention on the application of photothermal material in the ECL field.