Electrochemiluminescence Resonance Energy Transfer between Ru(bpy)₃²⁺ and CdZnSe@ZnSe Quantum Dots for Ovarian Cancer Biomarker Detection

Herein, an enhanced electrochemiluminescence resonance energy transfer (ECL-RET) from Ru(bpy)32+ to the core/shell CdZnSe@ZnSe quantum dots (CdZnSe@ZnSe QDs) was first designed for ovarian cancer biomarker analysis. The TiO2 metal–organic frameworks (TiO2 MOFs) were used as a promoter because of its unique semiconductor structure and high loading ability for Ru(bpy)32+. Additionally, the Envision complex with numerous horseradish peroxidases (HRPs) was employed to immobilize CdZnSe@ZnSe QDs, the acceptor of ECL-RET, which further improved the ECL emission of CdZnSe@ZnSe QDs. Concretely, reactive oxygen species (ROS), for instance, O2•– and OH•, were first yielded due to the catalytic ability of HRP to H2O2, followed by the electron from O2•– or hole from OH• injection into the CdZnSe@ZnSe QDs, triggering an extremely strong ECL response of CdZnSe@ZnSe QDs. On the basis of all of the above features, a highly effective ECL-RET biosensor was elaborately established to detect the targets in the range from 1.00 × 10–6 to 1.00 × 102 ng/mL with a low detection limit of 3.30 × 10–1 fg/mL (S/N = 3). This work opened up a new avenue for developing high-performance ECL-RET biosensors and demonstrated the high potential of the new biomarker in clinical ovarian cancer screening.