Visualization of MC-LR in lakes using near-infrared technology

Microcystin-LR (MC-LR), a secondary metabolite produced by cyanobacteria, poses significant ecological and health risks, particularly in lakes, where fluctuations in its concentration directly affect water quality and the living environment of nearby residents. However, the complexity of lake environments and the absence of suitable rapid monitoring tools have made long-term and extensive MC-LR monitoring challenging. This study proposed an effective monitoring tool based on near-infrared (NIR) fluorescence technology for the rapid assessment of MC-LR in lakes. The results demonstrated that the NIR fluorescent probe specifically binds to MC-LR, inducing changes in the fluorescence signal. Fluorescence analysis revealed a significant positive correlation between the probe's signal and MC-LR concentrations in lakes with varying pollution levels. Stepwise multiple linear regression and random forest analyses confirmed that fluorescence signal changes were primarily influenced by MC-LR. Additionally, the probe's long emission wavelength (699-783 nm) reduced background fluorescence interference, while its large Stokes shift (> 100 nm) minimized excitation light interference, significantly enhancing the signal-to-noise ratio of the measurements. The NIR fluorescent probe offers a promising solution for detecting MC-LR in natural lakes, advancing water quality monitoring by providing a rapid and reliable assessment tool.