A Water-Soluble Conjugated Polymer with Pendant Disulfide Linkages to PEG Chains: A Highly Efficient Ratiometric Probe with Solubility-Induced Fluorescence Conversion for Thiol Detection

Abstract

We investigated a water-soluble conjugated polymer (WSCP) with pendant disulfide linkages to poly(ethylene glycol) (PEG) chains, which is a highly efficient ratiometric probe with solubility-induced fluorescence conversion for thiol detection. This WSCP was doped with a low-bandgap fluorophore, 1,4-dithienyl benzothiadiazole (DBT), and was modified with PEGs by disulfide linkages to increase its water solubility. The free probe exhibited good solubility in aqueous solution (28 mg/mL) and showed purple fluorescence because of the low doping ratio of DBT. The separation of water-soluble PEG chains from the conjugated backbone induced by the cleavage of the disulfide linkages would lead to a significant decrease of the water solubility of the probe. The combined utilization of scanning electron microscopy, dynamic light scattering, and fluorescence spectrophotometer further confirmed that decreased solubility produced an aggregation of the hydrophobic conjugated backbone and subsequently increased fluorescen...