Label-free aptamer-based detection of microcystin-LR using a microcantilever array biosensor

Abstract

Cyanotoxins, produced by cyanobacteria, are a series of widely present toxins frequently found in fresh water during algal blooms. They are extremely hazardous and persistent, which makes them a serious threat to human and animal health. In this paper, we developed an aptamer-based microcantilever array sensor to detect microcystin-leucine-arginine (MC-LR), one of the most concerned liver toxin. For this assay, an easily synthesized thiol-modified aptamer with specific recognition for MC-LR was used as a probe. The aptamer was covalently and directionally immobilized on the gold surface of a microcantilever by one-step immobilization via its thiol group, which simplified the conventional preparation of micocantilever array sensors. Interactions between the immobilized aptamer and MC-LR successfully changed the surface stress of the microcantilever, resulting in a bending conformation. The detection range was from 1 to 500 μg L−1, and the cantilever deflection had a good linear relationship within the concentration range of 1–50 μg L−1. Additionally, this sensor could identify MC-LR from other congeners. Thus, the aptamer-based microcantilever sensor operated in stress mode could achieve simple, rapid, real-time, label-free and quantitative detection of MC-LR, making it a convenient and economical approach for MC-LR detection. The aptamer-based microcantilever array sensor has great potential for detecting various cyanotoxins while new aptamers specific for cyanotoxins are available, which may be developed to monitor the environment and protect life health.