Establishment of a rapid colorimetric sensor for Microcystin-LR based on specific aptamer and positively charged gold...

Eutrophication of surface freshwater drinking sources intensifies, leading blue-green algae to release massive microcystins. Microcystin-LR (MC-LR), the most toxic variant, poses severe threats to public health and environmental safety. Conventional MC-LR detection methods rely on bulky, expensive equipment and involve complex, time-consuming sample pretreatment, making them unsuitable for on-site testing. This study developed a colorimetric sensing platform based on the binding of positively charged gold nanoparticles (AuNPs) to MC-LR aptamers for simple and rapid MC-LR detection. Without MC-LR, positively charged gold nanoparticles bind to negatively charged aptamers, aggregate, and turn the solution from yellow to white. This method exhibits high sensitivity (detection limit: 0.1 μg/L) and good specificity (insensitive to interferents like MC-YR and MC-RR), with a total assay time of 55 min, providing a rapid alternative to conventional laboratory-based methods like ELISA. Tests on actual water samples showed recoveries of 96.1-119.8% with relative standard deviations <10%, demonstrating good accuracy and precision for real environmental water analysis. The method's performance suggests its potential for on-site screening, although some variability was observed in complex matrices. This visualized assay eliminates reliance on large instruments, shortens detection time, and holds great potential for environmental water sample testing.