Organic Photoelectrochemical Transistor/Visual Sensing Platform Based on CS/MCS Schottky Heterojunction and CRISPR/Cas12a-Driven Triple-Modal Synergistic Signal Amplification
Feixue Sun, Renjie Mao, Jiajing Li, Xuan Wang, Peiyu Hou, Hong Zhou
Abstract
Developing novel signal amplification and transduction technologies is the key to overcoming the bottlenecks of high-sensitivity and on-site detection in nucleic acid analysis. In this study, a dual-mode sensing platform based on organic electrochemical transistors (OPECT) and colorimetry was established to achieve ultrasensitive detection of miRNA-21. 1D/3D Co 9 S 8 /Mn 0.3 Cd 0.7 S Schottky heterojunction was synthesized as the photoactive material, which significantly enhanced the photoelectric conversion efficiency. The sensing and detection system cleverly integrated a quadruple signal amplification mechanism. The target triggered the catalytic hairpin assembly (CHA) reaction, generating H1 and H2 long chains. These chains activated the CRISPR/Cas12a system, which carried out nondiscriminatory cleavage to block the tandem strand displacement reaction (TSDR). This triggered the hybrid chain reaction (HCR) and formation of G-quadruplex/hemin DNAzyme (GQH DNAzyme), realizing cascade signal amplification. Under the catalysis of GQH DNAzyme, the detection had dual-signal outputs. It catalyzed the oxidation of 4-CN to form a deposition layer, inhibiting electron transport and achieving cascade signal amplification for OPECT. It catalyzed the H 2 O 2 -mediated TMB colorimetric reaction to complete the visual colorimetric analysis. Through triple-modal synergistic signal amplification of biological, chemical, and electronic modalities, this biosensing platform reduced the detection limits to as low as 36.5 aM and 3.8 fM, respectively. It provided a new solution for the accurate analysis of miRNA markers in the early diagnosis of cancer.