A dual-mode electrochemiluminescence/SERS biosensor for B-type natriuretic peptide based on a T7–CRISPR/Cas13a cascade and a CsPbBr3@PDA@Au perovskite interface

Abstract

B-type natriuretic peptide (BNP) is an important biomarker for cardiovascular diseases, motivating sensitive and robust quantification in complex matrices. Here we report a single-electrode, anti-correlated dual-mode electrochemiluminescence/surface-enhanced Raman scattering (ECL/SERS) biosensor that couples split-aptamer recognition with a solution-phase T7 transcription–CRISPR/Cas13a cascade and an interfacial toehold-mediated strand-displacement “probe-stripping” transduction on a CsPbBr₃@PDA@Au-modified glassy carbon electrode. BNP binding releases an active T7 template to generate trigger RNA, which activates Cas13a collateral cleavage to produce initiator strands for interfacial unlocking. The interface reaction removes ferrocene/Raman co-labeled probes, synchronizing ECL turn-on with SERS turn-off and enabling ratiometric quantification (R = I_ECL/I_SERS) to suppress common-mode variability. The sensor provides BNP determination over 0–10⁶ aM with log-linear single-mode calibrations and a continuous ratiometric response. Selectivity was validated against multiple interferents and the structurally related peptide NT-proBNP at the same concentration (10⁶ aM), showing negligible ratiometric change relative to BNP. Serum-sample evaluation and stability tests further support feasibility in complex matrices. This work establishes a cascade-to-interface ratiometric strategy for robust protein biosensing.