Title
Signal Amplification by Changing Counterions in Conjugated Polyelectrolyte-Based FRET DNA Detection
Author
Mijeong Kang, Okhil Kumar Nag, Rati Ranjan Nayak, Sungu Hwang, Hongsuk Suh, Han Young Woo
Year
2009
Journal
Macromolecules
Abstract
Two types of cationic polyfluorene copolymers (FHQ, FPQ) with a same π-conjugated structure but different counterions (bromide (BR), tetraphenylborate (PB)) were synthesized and studied as a fluorescence resonance energy transfer (FRET) donor to fluorescein-labeled DNA (ssDNA-Fl). The counterions accompanying the polymer chain for charge compensation are expected to perturb complexation with DNA and modify the fine-structure of D/A complex on molecular scale, which may influence the competition between the desirable FRET and energy-wasting charge transfer quenching. The PL quenching constant of ssDNA-Fl by Stern−Volmer plot was significantly reduced in the presence of the polymers with tetraphenylborate (4.3 × 106 M−1 for FHQ-BR vs 2.2 × 106 M−1 for FHQ-PB, 2.8 × 106 M−1 for FPQ-BR vs 1.3 × 106 M−1 for FPQ-PB). The resulting FRET-induced signal was amplified 2 to 8.6 times by exchanging bromide with tetraphenylborate as a counterion, suggesting a simple way for kinetic control of energy transfer to maximize signal amplification in conjugated polymer-based FRET biosensors.
Full Article
Instrument
FP-6500
Keywords
Fluorescence, FRET, Polymers, DNA structure, Materials, Biochemistry