Conjugated Polymers as Efficient Fluorescence Quenchers and Their Applications for Bioassays

We have developed a novel approach for simple and convenient detection of ligand−receptor interactions with high sensitivity and selectivity. The method harnesses a reversible fluorescence quenching between nonfluorescent polyelectrolyte quenchers and fluorescent probes tagged to ligands. Formation of more strongly bound ligand−receptor complexes forces the breakup of nonspecific, electrostatic interaction-based quencher/probe pairs to reverse the fluorescence quenching, triggering a fluorescence increase, and providing an off-to-on detection of the ligand/receptor interaction. Although a conjugated polyelectrolyte was used in the study, other nonconjugated polyelectrolyte quenchers are expected to work as well. The method should potentially find a wide variety of applications in several areas, ranging from drug screening, medical diagnostics, and biosensing to assay development.