DNA detection using water-soluble conjugated polymers and peptide nucleic acid probes

TLDR

The authors develop a homogeneous, real‑time DNA detection assay that uses cationic conjugated polymers to sensitize dye emission from a peptide nucleic acid (PNA) probe. Detection relies on PNA/DNA hybridization bringing the polymer and dye into Förster‑transfer proximity, with electrostatic interactions positioning the complex for efficient energy transfer. The assay achieves >25‑fold fluorescence amplification, enabling detection of 10 pM DNA with a standard fluorometer and demonstrating a simple, highly sensitive optical amplification platform.

Abstract

The light-harvesting properties of cationic conjugated polymers are used to sensitize the emission of a dye on a specific peptide nucleic acid (PNA) sequence for the purpose of homogeneous, “real-time” DNA detection. Signal transduction is controlled by hybridization of the neutral PNA probe and the negative DNA target. Electrostatic interactions bring the hybrid complex and cationic polymer within distances required for Förster energy transfer. Conjugated polymer excitation provides fluorescein emission >25 times higher than that obtained by exciting the dye, allowing detection of target DNA at concentrations of 10 pM with a standard fluorometer. A simple and highly sensitive assay with optical amplification that uses the improved hybridization behavior of PNA/DNA complexes is thus demonstrated.