Cholesterol-aminoacid conjugates treated filter paper-based photoluminescence indicator for nitroaromatic chemicals

Selective detection of different explosive materials is essential to the current world scenario from the perspective of health, safety, and environment. Here, we have developed and characterized a couple of bio-based conjugated systems, viz. cholesterol-tryptophan and cholesterol-cysteine for the detection of nitroaromatic explosive chemicals. The presence of tryptophan moiety introduces fluorescence property to the non-fluorescence cholesterol backbone, and hence it was used as a tag molecule to prepare photoluminescent filter papers which serve as indicators for picric acid and dinitrosalicylic acid. These paper strips undergo instant quenching in the presence of the experimental analytes under the UV irradiation, which could be visualized through the naked eye. The amount of quenching is found to be proportional to the concentration of the analytes. The limit of detection for picric acid and dinitrosalicylic acid was estimated to be about 33 nM and 48.7 nM respectively, and the mechanism of this quenching is mainly due to fluorescence resonance energy transfer between the fluorophore and the quencher. Also, the vapor of picric acid completely diminishes the photoluminescence of the filter papers. Such an easy, selective and instant detection of nitroaromatic chemicals is in high demand due to increasing health and security concern worldwide.