Highly sensitive detection of the hepatotoxin microcystin-LR by surface modification and bio-nanotechnology

A highly sensitive, portable method of detecting the hepatotoxin microcystin-LR (MC-LR) has been developed by a surface modification and gold nanoparticle (AuNP) technology. By using this technology a detection sensitivity of 0.1 pg μL−1 MC-LR can be reached which meets the standard of World Health Organization (WHO) requirements for the drinking water (1 μg μL−1 MC-LR) and compatible with those of conventional techniques, such as high-performance liquid chromatography (HPLC) and enzyme-linked immunosorbent assay (ELISA). Our method includes an inexpensive sensor, composed of a quartz crystal microbalance (QCM) along with gold nanoparticles (AuNPs), and a sandwiched immunoassay for rapid and in situ detection of MC-LR. The volume of analyte for once detection was generally less than 50 μL. The method specifically involves self-assembled monolayer formation on the QCM gold electrodes, immobilisation of MC-LR antibodies and AuNP signal amplification. It has been found that 30 nm is the optimal size for AuNPs which could effectively amplify the signals of MC. All the process was easily and promptly operated. Thus, a fast and convenient sandwiched immunoassay sensor has been established.