title: Optimization of interactions between a cationic conjugated polymer and chromophore-labeled DNA for optical amplification of fluorescent sensors.
abstract: Cationic conjugated polymers (CCPs) have been widely utilized as signal amplifiers in biosensors to improve the detection sensitivity through fluorescence resonance energy transfer (FRET) from CCPs to dye-labeled probes or targets. This paper investigates the effect of sodium dodecyl sulfate (SDS) on energy transfer between a cationic polyfluoreneethynylene copolymer (P1) and Texas Red labeled single-stranded DNA (ssDNA-TR). The presence of SDS in solution affects both the optical properties of P1 and TR emission within P1/ssDNA-TR complexes, which provides basic information on the role of SDS in FRET between P1 and ssDNA-TR. Although the quantum yield of P1 decreases in the presence of low concentrations of SDS, the presence of SDS reduces TR fluorescence quenching within P1/ssDNA-TR complexes and increases the number of optically active polymer repeat units within the proximity of TR, which are beneficial to P1-sensitized TR emission. In the absence of SDS, FRET from P1 to ssDNA-TR provides a 2.6-fold enhancement in TR emission intensity as compared to that upon direct excitation of TR at 595 nm. At the optimum SDS concentration (5 microM), P1-sensitized TR signal output increases to 11.3-fold relative to direct excitation of TR. This study highlights the importance of modulation of the CCP/ssDNA-dye interaction in improving the signal output of dye-labeled DNA by CCP through FRET.
authors.affiliation: Department of Chemical and Biomolecular Engineering, National University of Singapore, Singapore.
authors.forename: Kan-Yi
authors.initials: KY
authors.lastname: Pu
authors.forename: Summer Yi-Hui
authors.initials: SY
authors.lastname: Pan
authors.forename: Bin
authors.initials: B
authors.lastname: Liu
mesh_terms: D002412:Cations / Q000737:chemistry; D004277:DNA, Single-Stranded / Q000737:chemistry*; D031541:Fluorescence Resonance Energy Transfer; D008163:Luminescent Measurements; D015394:Molecular Structure; D011108:Polymers / Q000737:chemistry*; D013499:Surface Properties; D013501:Surface-Active Agents / Q000737:chemistry
chemical_list: D002412:Cations; D004277:DNA, Single-Stranded; D011108:Polymers; D013501:Surface-Active Agents