OPECT-smartphone-photothermal imaging multimodal biosensor based on HOF-101@CdS coupled with target induced ion exchange reaction for GTX 1/4 detection

Traditional organic photoelectrochemical transistor (OPECT) biosensing offers high sensitivity and cost-effectiveness for bioanalytical applications, but its reliance on single-signal output limits reliability in complex biological systems. To address this limitation, a novel multimodal biosensing platform was developed by integrating OPECT with smartphone colorimetry (SCL) and photothermal imaging (PTI) for gonyautoxin 1/4 (GTX 1/4) detection. The system employed a HOF-101@CdS as photoactive material, where GTX 1/4 triggers competitive binding that releases DNA nanowires and CuO-DNA probes from magnetic bead complexes. Subsequent acid treatment liberates Cu 2+ ions, which undergo ion exchange with HOF-101@CdS to form photothermally active and color-changed CuS. This dual-response mechanism enables three complementary detection modes: OPECT measured photocurrent changes, SCL monitored the yellow-to-dark color transition from CdS to CuS, and PTI quantified heat generation from CuS. The integrated platform achieves exceptional sensitivity with detection limits of 0.097 nM (OPECT) and 0.1 nM (SCL), while maintaining a high selectivity against interfering substances. The photothermal component further enabled rapid visual assessment using portable infrared imaging. Successful application in real-sample analysis demonstrated the system’s practical utility for marine toxin monitoring. This OPECT-SCL-photothermal approach overcomes traditional limitations through multi-signal cross-validation, significantly enhancing measurement reliability while preserving the advantages of portability and operational simplicity. The synergistic combination of electronic, optical, and thermal detection modalities establishes a new paradigm for field-deployable biosensing with built-in verification capability, particularly valuable for environmental monitoring and food safety applications.