Qualitative and quantitative detection of microcystin-LR based on SERS-FET dual-mode biosensor

Microcystin-LR (MC-LR), a kind of hepatoxin produced by cyanobacteria blooms, can promote liver cancer through long-term exposure even at low concentrations. In this study, a novel biosensor based on surface-enhanced Raman scattering (SERS) and field effect transistor (FET) dual sensing mode was developed by using gold nanoparticles (AuNPs)/graphene composite as sensing material. Based on the SERS sensing mode, the Raman fingerprint spectrum of MC-LR was obtained through the specific combination of MC-LR aptamer and MC-LR. The SERS enhanced effect of the AuNPs was also verified by theoretical simulation. By using FET sensing mode, the graphene field effect transistor (G-FET) biosensor respectively exhibited the detection limit as low as 0.62 aM and 0.91 aM in phosphate buffered saline (PBS) and human serum, and showed a good linear relationship in a wide range of 1 × 10^-18 to 1 × 10^-8 M in both solutions. Meanwhile, the sensor was utilized for the detection of MC-LR in actual water samples, and the complex components in the water did not interfere with MC-LR detection, indicating a significant high specificity of the sensor. The SERS-FET dual-mode biosensor can provide more detection options and improve the reliability of measurement results, which may has a great application prospect in the field of water environment detection.