Sensitive Detection of Nitroaromatics With Colloidal Conjugated Polymer Nanoparticles

We observe more than two orders of magnitude enhancement of fluorescence quenching in colloidal conjugated polymer nanoparticles by nitroaromatic analytes compared to solution of the same polymer in organic solvents. This observation is surprising as the quantum efficiency of fluorescence of the polymer solution is significantly higher. The colloidal nanoparticle dispersions of substituted polythiophene derivative are fabricated by the surfactant-assisted mini-emulsion technique. Stern-Volmer constants are determined using both one-photon and two-photon excitation methods. We believe strong analyte-nanoparticle interaction results in the large value of the Stern-Volmer constants measured. The nanoparticle-based sensor described here is suitable for developing a field-based sensory device for detecting a broad class of nitroaromatics in solution.