A pyrene-based ratiometric probe for nanomolar level detection of glyphosate in food and environmental samples and its application for live-cell imaging

Abstract

A reversible chromogenic probe based on a pyrene-linked bispicolyl amphiphile has been utilized for ratiometric, nanomolar level (LOD: 1.3 nM) detection of glyphosate in Brij-58 micelle medium. The probe shows a change in solution color from greenish-yellow to colorless with Cu²⁺ ions along with fluorescence quenching. When the solution was subsequently exposed to glyphosate, a ratiometric color-change from colorless to greenish-yellow was noticed, in addition to a turn-on fluorescence (green) response. Mechanistic investigations indicate dissociation of the preformed metal complex (1·Cu²⁺) in the presence of glyphosate, which triggers the release of unbound probe in the reaction medium. When 1·Hg²⁺ was used as the recognition template instead of 1·Cu²⁺, no interaction was observed with glyphosate. Considering its high sensitivity, 1·Cu²⁺ was further utilized for screening of real-life samples, such as water, soil, crops and packaged food items. Finally, the present sensory system is utilized for fluorescence bioimaging of intracellular glyphosate.