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Modulation of Charge Density of Cationic Conjugated Polyelectrolytes for Improving the FRET‐Induced Sensory Signal with Enhanced On/Off Ratio
Author(s) -
Jeong JiEun,
Jung In Hwan,
Kim Boram,
Le Van Sang,
Woo Han Young
Publication year - 2016
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.201500304
Subject(s) - förster resonance energy transfer , cationic polymerization , polyelectrolyte , conjugated system , solubility , ionic bonding , chemistry , electrostatics , ionic strength , oligonucleotide , charge density , fluorescence , dna , supramolecular chemistry , polymer , aqueous solution , ion , polymer chemistry , molecule , organic chemistry , optics , biochemistry , physics , quantum mechanics
Three types of cationic polyfluorenes with a different number of ionic groups are synthesized to modulate their solubility in water and the interactions with anionic oligonucleotide probes (DNA‐C). Increasing the charge density improves the water‐solubility of conjugated polyelectrolytes (CPEs) but decreases its optical antenna effect in the electrostatic sensory platform (CPE/DNA‐C), resulting in low fluorescence resonance energy transfer (FRET) signal. With increasing charge density in CPE, the concentration of conjugated units in CPE/DNA‐C decreases at [+]:[−] = 1:1, after which little driving force is expected to bring positive CPEs and negative DNA‐C into close proximity for efficient FRET. CPF2 with 2 ionic groups (per repeat unit) and hydrophilic polyether side‐chains exhibits good water‐solubility and a higher FRET signal with an enhanced signal on/off ratio. In addition, the charge density in CPEs modulates the range of sensory responses by forming a tighter or weaker electrostatic CPE/DNA‐C complex, which perturbs the probe‐target binding interactions.