CeO2/MXene heterojunction-based ultrasensitive electrochemiluminescence biosensing for BCR-ABL fusion gene detection combined with dual-toehold strand displacement reaction for signal amplification

An on-off nonenzymatic and ultrasensitive electrochemiluminescence (ECL) biosensing platform has been constructed to detect BCR-ABL fusion gene based on CeO2/MXene heterojunction and configuration-entropy driven dual-toehold strand displacement reaction (DT-SDR) for signal amplification. The CeO2/MXene hetero-junction were prepared via one-step hydrothermal method through in situ synthesis of CeO2 nanocubes on the surface of Ti3C(2)-MXene nanosheets. Surprisingly, the prepared CeO2/MXene heterojunction with good dispersion and excellent conductivity not only significantly enhanced ECL emission of S2O1-/O-2 system, but also acted as good electrode modification materials to provide massive active sites for three-stranded ST/AS/BK complex immobilization. In the presence of target BCR-ABL fusion gene and Bio-FS, target BCR-ABL fusion gene bound to dual-toehold exposed at the ends of ST, replacing AS and BK and obtaining ST/target with a loop. Subsequently, Bio-FS bound to the loop (as toehold) in ST strand of ST/target to form ST/Bio-FS, replacing the target to further trigger a new SDA cycle. This configuration-entropy driven DT-SDR made three-stranded ST/AS/BK complex transform into dual-stranded ST/Bio-FS in the electrode interface. Ultimately, the quenching labels of strepta-vidin modified Pt nanoparticles functionalized polydopamine composites (SA-Pt@PDA) were introduced via biotin and streptavidin recognition, realizing ECL emission quenching of S2O1-/O-2 system for on-off detection of BCR-ABL fusion gene. The developed ECL biosensor for BCR-ABL fusion gene detection achieves the wide concentration variation from 1 fM to 100 pM with low limit of detection down to 0.27 fM, which provides new enlightenment and basis for molecular diagnosis of chronic myelogenous leukemia in clinical practice.

Automated summary

An on-off nonenzymatic and ultrasensitive electrochemiluminescence biosensing platform for detecting BCR-ABL fusion gene has been developed based on CeO2/MXene heterojunction and configuration-entropy driven dual-toehold strand displacement reaction. This platform achieves wide concentration variation and low limit of detection, providing new insights for molecular diagnosis of chronic myelogenous leukemia in clinical practice.