Recent advances in optical sensors for microcystin-LR: from recognition elements to signal transduction

Microcystin-leucine-arginine (MC-LR), stands out as the most lethal and broadly occurring variant of microcystins, which are harmful substances generated by cyanobacteria during periods of excessive nutrient enrichment in water bodies. Even at low levels, MC-LR can cause acute or chronic hepatic injury, leading to inflammation and potentially promoting tumorigenesis, thereby imposing a significant burden on human health. Vigilant surveillance of MC-LR is vital for safeguarding both the well-being of the public and environmental security. Optical sensors are particularly advantageous for the detection of MC-LR, owing to their exceptional sensitivity and ease of use. This review presents a comprehensive overview of the current advancements and emerging trends in optical sensors for MC-LR detection, focusing on two primary aspects: recognition elements and optical signal transduction. Recognition elements, including enzymes, antibodies, molecular imprinted polymers (MIPs), and aptamers, are summarized along with their characteristics. The review also thoroughly discusses optical signal transduction and its performance, specifically addressing colorimetry, fluorescence, surface-enhanced Raman scattering (SERS), surface plasmon resonance (SPR), electrochemiluminescence (ECL) and other signal transduction methods. Additionally, the review provides a summary of the achievements and challenges of current optical sensors, as well as future application prospects for MC-LR optical sensors. This systematic review aims to facilitate the further development of optical sensors for detecting microcystins.