A colorimetric and fluorescent dual-responses chemosensor (PT3, a water-soluble polythiophene) for streptomycin was designed and synthesized. The structure of PT3 was characterized by using infrared spectroscopy, ¹H NMR and gel-permeation chromatography analyses. The conformational change of PT3induced by streptomycin resulted in the red shift of absorption spectra and fluorescent quenching. Moreover,PT3 showed excellent selectivity for streptomycin over other antibiotics and biomolecules. PT3 could quantificationally detect streptomycin in the range of 2–70 μM with a detection limit of 0.2 μM (116 ppb), which is lower than the maximum residue limit defined by World Health Organization (200 ppb).

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2014

Molecular structures of PT3, streptomycin, and the proposed interaction mechanism between PT3 and streptomycin.