Self-assembled fluorescent nanosensor for ultrafast and field-deployable monitoring of herbicide fomesafen in multiple matrices

The rising demand for ultrasensitive, field-deployable detection technologies has intensified interest in nanoprobe-based monitoring of environmental contaminants. Fomesafen (FSA), a widely used post-emergence agricultural herbicide, poses significant ecological and health risks due to its slow degradation and prolonged environmental persistence. Addressing the need for rapid in situ detection, we propose a novel turn-on fluorescent nanoprobe (RBO) that combines small-molecule self-assembly, target-triggered disassembly, and adaptive signal amplification to achieve highly sensitive and quantitative detection of FSA. This "immediate-response" system exhibits exceptional performance, including high selectivity, sub-minute response time (< 1 min), high sensitivity (LOD = 0.39 µM), and a dual fluorescent-colorimetric readout that enhances detection reliability. Field applications demonstrate that the nanoprobe supports diverse use cases, enabling on-site quantification of FSA on food surfaces and in soil, as well as real-time visualization and localization of FSA in plant tissues and zebrafish models for accurate assessment of pesticide-induced crop damage and ecological risk. Additionally, RBO has been adapted into test strips and hydrogel-based portable sensors and integrated with smartphone-imaging workflows, substantially improving on-site detection efficiency and device miniaturization. Collectively, this nanoprobe offers a powerful and reliable platform for monitoring FSA across agricultural, environmental, and biological matrices.