A turn-on fluorescent nanoprobe based on N-doped silicon quantum dots for rapid determination of glyphosate.

Abstract

N-Doped silicon quantum dots (N-SiQD) were synthesized using N-[3-(trimethoxysily)propyl]-ethylenediamine and citric acid as silicon source and reduction agent, respectively. The N-SiQD shows a strong blue fluorescence with a high quantum yield ofabout 53%. It is found that a selective static quenching process occurs between N-SiQDs and Cu2+. Glyphosate can inhibit this phenomenon and trigger the rapid fluorescence enhancement of the quenched N-SiQDs/Cu2+ system due to the specific interaction between Cu2+ and glyphosate. With such a design, a turn-on fluorescent nanoprobe based on N-SiQD/Cu2+ system was established for rapid determination of glyphosate. The determination signal of N-SiQD/Cu2+ was measured at the optimum emission wavelength of 460nm after excitation at 360nm. Under optimal conditions, the turn-on nanoprobe showed a linearrelationship between fluorescent response and glyphosate concentrations in therange 0.1 to 1μgmL-1. The limit of determination was calculated to 7.8ngmL-1 (3σ/S). Satisfactory recoveries were obtained inthe determination of spiked water samples, indicating the potential use forenvironmental monitoring. Graphical abstract Schematic representation of N-SiQD/Cu2+ system for glyphosate determination. Fluorescence quenching of N-SiQDs induced by copper ions and the succedent fluorescent "turn on" triggered by glyphosate.