Dual catalytic hairpin assembly and enzyme cascade catalysis amplification based sensitive dual-mode biosensor with significantly enhanced opposite signal readout

Herein, a sensitive photoelectrochemical-electrochemical (PEC-EC) dual-mode biosensor with opposite readout signals was constructed for sensitive and accurate detection of miRNA-21, which based on the dual catalytic hairpin assembly (dual CHA) and enzyme cascade catalysis amplification. Firstly, dual CHA could transform a small amount of target into substantial output DNA for achieving efficient conversion between target and output signal. Moreover, the multifunctional carbon nitride material (NaKCN-MB), synthetized through g-C3N4 co-doping by K+, Na+ ions and compounding with organic dye MB, could be not only as the ternary self-enhanced photoactive material, but also as glucose oxidase (GOx)-mimicking enzyme to generate in situ H2O2 as an intermediate that subsequently decomposed by hemin polymer for acquiring a direct electron transfer-based enzyme cascade electrocatalytic system. The proposed approach accomplished the simultaneous cascade amplification in PEC and EC dual-mode detection system with opposite readout signals, which effectively resolved the low sensitivity and accuracy in traditional biosensors. As a result, the proposed dual-mode detection approach exhibited a wide detection range of 0.1 fM to 1 nM for PEC detection and 1 fM to 1 nM for EC detection, which provided an efficient and universal biosensing avenue, possessing great meaning in biological analysis and disease diagnosis.