Highly Sensitive Detection of Nitro Compounds Using a Fluorescent Copolymer-Based FRET System
Vishal Kumar, Saurabh K. Saini, Neha Choudhury, Anshu Kumar, Binoy Maiti, Priyadarsi De, Mahesh Kumar, Soumitra Satapathi
Abstract
We report here that optically resonant donor copolymers are used to amplify the sensitivity of an electron-rich fluorescent copolymer toward electron-deficient nitroaromatic compounds (NACs). In a polymer–polymer system, we found that ultrafast Förster resonance energy transfer (FRET) enhances the sensitivity of the primeval fluorescent polymer sensor by 6-fold approximately toward the conventional NACs like 2,4-dinitrotoluene (DNT), 2,4,6-trinitrotoluene (TNT), and 2,4,6-trinitrophenol (TNP). The present article reports an optical sensor for sensitive detection of NACs by using a fluorescent probe based on FRET phenomena between P[DMA-co-(Boc-Trp-EMA)] (RP) bearing a tryptophan derivative as a donor and P[MMA-co-(Ala-HEMA)-co-(Dansyl-Ala-HEMA)] (DCP) bearing a dansyl derivative in the side chain as an acceptor. This elegant method thus paves the way to achieving a sensitivity <1 μM with a very high value of Stern–Volmer constant. Further, UV–vis absorbance spectroscopy, cyclic voltammetry, ultrafast transient absorption spectroscopy, time-resolved, and steady-state fluorescence spectroscopy were performed to establish the quenching mechanism comprehensively. We also carried out a contact mode analysis in solid-state phase through strip tests for visual detection of NACs in ambient conditions. This unique and quality performance of our sensing probe makes it convenient for naked-eye detection and therefore gives an escalation for stand-alone sensors for NACs, particularly reinforcement in the field of analytical and forensic sciences.