Sensitive fluorescence 'off-on' switch system for catechins detection based on water-soluble polythiophene derivatives

摘要

Because catechins (CCs) play an important role in human health, we proposed a new CCs detection method relying on a novel fluorescence "off-on" switch system. Water-soluble cationic polythiophene derivatives, denoted as poly 3-{[l-(2-hydrazino-2-oxopropyl)piperidin-4-ylidene]methyl}thiophene hydrochloride (PMTH-HCl), was prepared as a novel fluorescent material. Initially, the fluorescence of PMTH-HCl can be quenched by Cu~(2+) because of the spontaneous formation of Cu~(2+)-PMTH·HCI assembling dyads, resulting in fluorescence turn off. Then, on the addition of CCs in Cu~(2+)-PMTH·HCl, Cu~(2+) was separated from PMTH-HCl, producing free PMTH-HCl and stable complex Cu~(2+)-CCs, resulting in the turn on of the fluorescence signal of PMTH-HCl. Meanwhile, the mechanisms of fluorescence quenching and recovery were discussed to provide new ideas for designing sensors based on water-soluble conjugated polymers.