Design and mechanistic study of a high-sensitivity small-molecule fluorescent probe for the detection of microcystin-LR

Abstract

Cyanobacterial bloom-derived microcystin-LR (MC-LR) poses serious threats to aquatic ecosystems and human health, while conventional analytical methods often require expensive instrumentation and labor-intensive procedures. Herein, we report a small-molecule fluorescent probe for MC-LR detection, synthesized via a simplified route and structurally confirmed by ¹H NMR, ¹³C NMR, FT-IR and HRMS. The probe exhibited a concentration-dependent fluorescence enhancement toward MC-LR over 0–100 μM with good linearity (R² = 0.982) and a low detection limit of 0.507 μM. Reliable performance was maintained under near-neutral conditions (pH 6–9), along with excellent photostability and strong anti-interference capability against 10 common amino acids. Zebrafish embryo assays further demonstrated low toxicity of the probe. Mechanistic investigations suggest that the fluorescence response arises from synergistic recognition driven by π–π stacking interactions between the probe and the aromatic moieties of MC-LR, together with long-chain binding dominated by hydrophobic association with the aliphatic segment of MC-LR, which facilitates electron transfer and amplifies the emission signal. Overall, this probe provides a rapid and reliable platform for MC-LR detection in practical water matrices.