Synergistic enhancement of porphyrin-based MOFs with Au@Ag core-shell nanoparticles for label-free photoelectrochemical-surface enhanced Raman scattering dual-mode biosensing of microcystin-LR

Microcystin-LR (MC-LR), the most toxic cyanotoxin, poses severe threats to aquatic ecosystems and human health even at trace level, thus requiring ultrasensitive and rapid detection. In this work, a label-free photoelectrochemical-SERS (PEC-SERS) dual-mode aptasensor is proposed that employs Zn-TCPP MOFs simultaneously as PEC and Raman reporter, eliminating extra probe and simplifying fabrication; Au@Ag core-cell nanoparticles (NPs) with intense surface plasmon resonance amplify both photocurrent and SERS signals of Zn-TCPP. The fabricated aptasensor is based on the specific binding of MC-LR by the conjugate of Au@Ag NPs and aptamer to depress PEC and SERS signals from Zn-TCPP. It offered two linear ranges of 0.01–10 ng mL −1 and 0.03–30 ng mL −1 in PEC and SERS mode, respectively, and the corresponding detection limits are 0.0001 ng mL −1 (PEC mode) and 0.003 ng mL −1 (SERS mode). Dual readouts afford high selectivity, reproducibility and stability, validated in real waters with satisfactory recoveries. This work offers a simple but efficient way to construct PEC-SERS dual mode biosensing platform and should promote the application of this method.