Heterolinker MOFs synergized with entropy-driven DNA amplification for precision dual-mode sensing of Microcystin-LR.

To overcome the high risk of false results in single-mode detection for environmental toxins, a self-validating dual-mode biosensing platform integrating photoelectrochemical (PEC) and fluorescence (FL) signals was developed for the ultrasensitive detection of Microcystin-LR (MC-LR). The sensor of core innovation lies in a heterolinker-engineered metal-organic framework (MOF), where the incorporation of 1,4-diazabicyclo [2.2.2] octane (Dabco) transformed a two-dimensional Zn-tetrakis (4-carboxyphenyl) ethylene (Zn-TCBPE) layer into a stable three-dimensional Zn-TCBPE-Dabco architecture. This structural transition dramatically enhanced charge separation and created an ideal matrix for dual-signal generation. For precise biointerface assembly, an entropy-driven DNA amplification circuit was employed to in situ construct Y-shaped DNA nanostructures, which hierarchically organized the MOF units on a CdS-modified electrode, establishing a cascading energy alignment. This design enabled directed electron flow, synergistically amplifying the PEC response while maintaining stable FL output. The biosensor achieved exceptional sensitivity with detection limits of 3.2 × 10-6 ng/mL (PEC) and 4.7 × 10-6 ng/mL (FL). By leveraging the orthogonal nature of the two signals, the platform providing intrinsic mutual verification, effectively eliminating false positives/negatives and offering a reliable tool for high-fidelity monitoring in complex aquatic environments.