Fluorescence turn-on chemical sensor based on water-soluble conjugated polymer/single-walled carbon nanotube composite

A chemical sensor for methyl viologen (MV2+), based on a water-soluble conjugated polymer/single-walled carbon-nanotube (SWNT) composite, was fabricated. Water-soluble poly(m-phenylene ethynylene) with sulfonic acid side-chain groups (mPPE-SO3) was synthesized via a Pd-catalyzed Sonogashira coupling reaction and used to prepare a highly stable mPPE-SO3/SWNT composite with strong - interactions in water. The relationship between the optical properties and sensing capability of the mPPE-SO3/SWNT composite in aqueous solution was investigated. The addition of MV2+ enhanced the fluorescence intensity of the mPPE-SO3/SWNT composite by inducing a conformational change of the polymer from a helical to a random-coil structure. The water-soluble mPPE-SO3/SWNT composite enabled highly sensitive fluorescence detection of MV2+ in aqueous solutions with no precipitation resulting from reaggregation of the SWNTs. This mPPE-SO3/SWNT composite sensor system is therefore an effective turn-on chemical sensor for MV2+. (C) 2016 Wiley Periodicals, Inc.