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.

Schematic diagram of the step-by-step fabrication of the QCM immunosensor chip. MPA at 2% was first absorbed on the QCM via a specific thiol–gold interaction, followed by mAb (10 μL of 150 pg μL−1) immobilisation by replacing the NHS ester of a chemically modified gold electrode of the QCM. The unreacted NHS esters were then blocked using 10 μL of a 3% BSA solution. Next, 10 μL of a MC-LR solution was applied to the gold electrode. Finally, an amplifying AuNP–mAb solution was applied to the QCM to augment the immunoassay response.Figure optionsDownload as PowerPoint slide