A Multiple-Responsive Fluorescence Probe Based on Water-Soluble Fluorescent Conjugated Polymer for Biomolecules Detection

Abstract

In this paper, we designed a multiresponsive fluorescent probe based on a synthetic water-soluble conjugated fluorescent polymer (PF-DBT-S-S-PDI) consisting of the conjugated fluorescent backbones and the hydrophilic side chains connected by a disulfide bond. Based on its specific structures, according to two different response mechanisms of fluorescence resonance energy transfer (FRET) and heavy atom effect, the polymer shows high sensitivity and selectivity toward reductive species-thiols and oxidizing substances (such as H2O2) in different ways. Owing to the presence of disulfide bonds, the reductive mercaptan in the solution would cause the water-soluble branches in the micellar structure to break off and leave, which causes the hydrophobic framework of the polymer to aggregate and enhance the fluorescence intensity. On the other hand, because the PDIs in branches are ionic polymers with many iodide ions, H2O2 in solution oxidizes iodide ions into iodide so that the heavy atomic effect of iodide would quench the fluorescence. Both mechanisms have high sensitivity; e.g., the detection limits for mercaptan (such as cysteine) were 0.052 mM, 5.26 μM for H2O2, and 1.06 μM for glucose (combined with oxidase). The multiple detection ability of the polymer has been validated by evaluating free thiols and glucose levels in food samples and tissue homogenates. Our work provided a strategy for integrating multiple species detection capabilities on a single probe.

Preparation of a Fluorescent Polymer Sensing System with an Oxidation-Electric Dual-Mode Response Based on the Supramolecular Host–Guest Interaction

“…Polymer fluorescent probes not only maintain the properties of small monomers but also exhibit unique properties due to the polymeric synergistic effect . Our group has constructed several fluorescent sensing systems for biomedical applications utilizing polymers as backbones. − The fluorescent sensing systems that utilize polymers as backbones have overcome the issues of easy aggregation, light scattering interference, and photobleaching of individual dye molecules in various applications. , These systems have shown high binding constants, detection sensitivity, photostability, ease of modification, biocompatibility, and multitarget detection. − …”