SERS detection of glyphosate via competitive Cu(II) displacement from a DNA-stabilized chromophore complex

Glyphosate (GLYP) is the most extensively used herbicide worldwide and a widespread contaminant in both environmental and food matrices. Its potential adverse health effects and broad distribution underscore the need for sensitive and accessible detection methods beyond conventional approaches. In this work, we present a surface-enhanced Raman spectroscopy (SERS)-based sensing platform for GLYP detection, relying on the displacement of Cu(II) ions from a molecular complex composed of Alizarin Red S (ARS) intercalated into short double-stranded DNA (dsDNA). Disruption of the ARS-Cu(II) complex by GLYP induces concentration-dependent changes in the SERS spectral signature of the chromophore. A linear calibration curve was obtained in the range of 1-200 μM GLYP, with a detection limit of ∼80 nM. The method also exhibited excellent reproducibility across operators and laboratories. Finally, the sensor was validated in a rice water extract matrix used as a representative food-derived medium, showing high recovery and minimal matrix interference under controlled conditions. These findings highlight the potential of this SERS platform as a rapid and sensitive analytical approach for glyphosate detection.