Gold nanobipyramid-based colorimetric sensor for rapid on-site detection of microcystin-LR in drinking water

In recent years, algal blooms have occurred frequently. Microcystin-LR (MC-LR), a harmful metabolite produced by cyanobacterial cells, is widely distributed in water environments worldwide. MC-LR can enter the human body through drinking water. Humans may suffer from its severe hepatotoxicity, which in extreme situations may result in fatalities and incidents involving public health and safety. Therefore, a detection method based on chicken yolk antibody, immunomagnetic separation technology and gold nanobipyramids (AuNBPs) colorimetric technology was developed for visual qualitative and semi-quantitative detection by color change of AuNBPs solution. The competitive reaction system of MC-LR with thiol-conjugated IgG antibody (IgG-SH) was also established by combining the second antibody competition method. In this system, the concentrations of MC-LR and IgG-SH were negatively correlated, with MC-LR dominating and occupying the IgY site first. The remaining IgG-SH reacting with AuNBPs. The thiol group of IgG-SH causes a shift in the color and absorption peak of AuNBPs by inhibiting their growth. Therefore, the concentration of MC-LR can be quantified by establishing an equation between the peak shift of AuNBPs. The developed sensor has a detection time of 2.5 h, which is relatively short, with clear and distinguishable colors. The visual detection limit is 1 μg/L, and the minimum detection limit is 0.82 μg/L. It has good specificity and repeatability, the recovery rate is between 88.72 % and 107.79 %, and the standard deviation is between 1.84 % and 13.86 %. The method we established has practical application value and prospects.