Photophysical Diversity of Water-Soluble Fluorescent Conjugated Polymers Induced by Surfactant Stabilizers for Rapid and Highly Selective Determination of 2,4,6-Trinitrotoluene Traces

Abstract

The increasing application of fluorescence spectroscopy in development of reliable sensing platforms has triggered a lot of research interest for the synthesis of advanced fluorescent materials. Herein, we report a simple, low-cost strategy for the synthesis of a series of water-soluble conjugated polymer nanoparticles with diverse emission range using cationic (hexadecyltrimethylammonium bromide, CTAB), anionic (sodium dodecylbenzenesulfonate, SDBS), and nonionic (TX114) surfactants as the stabilizing agents. The role of surfactant type on the photophisical and sensing properties of resultant polymers has been investigated using dynamic light scattering (DLS), FT-IR, UV-vis, fluorescence, and energy dispersive X-ray (EDS) spectroscopies. The results show that the surface polarity, size, and spectroscopic and sensing properties of conjugated polymers could be well controlled by the proper selection of the stabilizer type. The fluorescent conjugated polymers exhibited fluorescence quenching toward nitroaromatic compounds. Further studies on the fluorescence properties of conjugated polymers revealed that the emission of the SDBS stabilized polymer, N-methylpolypyrrole-SDBS (NMPPY-SDBS), is strongly quenched by 2,4,6-trinitrotoluene molecule with a large Stern -Volmer constant of 59 526 M(-1) and an excellent detection limit of 100 nM. UV-vis and cyclic voltammetry measurements unveiled that fluorescence quenching occurs through a charge transfer mechanism between electron rich NMPPY-SDBS and electron deficient 2,4,6-trinitrotoluene molecules. Finally, the as-prepared conjugated polymer and approach were successfully applied to the determination of 2,4,6-trinitrotoluene in real water samples.

Hybrid Optoelectrochemical Sensor for Superselective Detection of 2,4,6-Trinitrotoluene Based on Electrochemical Reduced Meisenheimer Complex

“…Therefore, the determination of this explosive compound is very important. Up until now, several methods have been applied for detection of TNT which may be time-consuming, selectively low, laborious, and expensive, including colorimetric sensors, − fluorescence sensors, , ion mobility spectrometry (IMS), liquid chromatography coupled to mass spectrometry (LC–MS), gas chromatography coupled to mass spectrometry (GC/MS), gas sensors, electrochemical sensors, and nanosensor arrays . The fabrication of absorbance based spectroscopic sensors for TNT is a serious challenge, as the absorption spectrum of TNT shows no peaks in the visible region. , One common candidate for fast and easy detection of TNT is the colorimetric probe based on donor–acceptor interactions between primary amines and TNT, named as “Meisenheimer complex”. , TNT is able to form a Meisenheimer complex with amine molecules due to the presence of powerful electron-withdrawing nitro groups .…”

“…The fabrication of absorbance based spectroscopic sensors for TNT is a serious challenge, as the absorption spectrum of TNT shows no peaks in the visible region. , One common candidate for fast and easy detection of TNT is the colorimetric probe based on donor–acceptor interactions between primary amines and TNT, named as “Meisenheimer complex”. , TNT is able to form a Meisenheimer complex with amine molecules due to the presence of powerful electron-withdrawing nitro groups . The TNT molecule, as a Brønsted–Lowry acid, accepts the lone-pair electrons of organic amines at the methyl site. ,, In the literature, there are several reports that use the advantages of the Meisenheimer complex for determination of TNT and other NACs by using chemical sensors. ,,− In addition, we have recently developed a water-soluble fluorescent conjugated DBS-doped N -methylpolypyrrole and a chemiresistor gas sensor based on modified conducting polypyrrole (PPy) film for determination of TNT …”

A nanoporous gold-based electrochemical aptasensor for sensitive detection of cocaine

“…22 In the past two decades, aptamer-based biosensors with high specicity and affinity have become a signicant diagnostic tool for capturing and detection of a wide number of analytes ranging from small molecules, 23,24 ions, 25,26 peptides, 27 proteins 28 and cells. 29 Nanotechnology has been widely used as an efficient tool to improve the sensitivity of all kinds of sensors and biosensors including aptasensors by signal amplication on a wide variety of nanomaterials and nanostructures such as metal nanoclusters and nanoparticles, 30-32 electrospun nano-bers, 33,34 conjugated polymers [35][36][37] and carbon-based materials. 38 The integration of electrochemical detection techniques with aptamer-and nano-technologies is a unique combination, enabling the development of highly advanced sensing platforms for detection of almost all kinds of target analytes in a sensitive, selective, fast and reliable manner.…”

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“…Conducting polymers were considered as the futuristic new materials that would lead to the next generation of electronics and optoelectronics devices. Among all conducting polymers PANi and its derivatives have attracted much attention worldwide because of chemical stability, simple preparation and high conductivity, low ionization potential, high electron affinity and the ability to be oxidized or reduced more reversibly than conventional polymer [1][2][3]. PANi has extended π-electron delocalization, which is responsible forfluorescence emission and it is a fluorescent conjugated polymer.…”