Ternary System Based on Fluorophore–Surfactant
AssembliesCu<sup>2+</sup> for Highly Sensitive and Selective Detection of Arginine in Aqueous
Solution
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Abstract
A new cationic dansyl derivative-based
(DIlSD) fluorescence probe
was designed and synthesized. Its combination with anionic surfactant
SDS assemblies shows enhanced fluorescence intensity and blue-shifted
maximum wavelength. Its fluorescence can be slightly quenched by Cu<sup>2+</sup>; however, the fluorescence quenching efficiency by Cu<sup>2+</sup> is highly increased upon titration of arginine (Arg). As
a result, the ternary system containing the cationic fluorophore,
anionic surfactant, and Cu<sup>2+</sup> functions as a highly sensitive
and selective sensor to Arg. The optimized sensor system displays
a detection limit of 170 nM, representing the highest sensitivity
to Arg in total aqueous solution by a fluorescent sensor. Control
experiments reveal that the imidazolium groups in the fluorophore,
the anionic surfactant, and Cu<sup>2+</sup> all play important roles
in the process of sensing Arg. The electrostatic interaction between
the cationic fluorophore and anionic surfactants facilitates the binding
of imidazolium rings with Cu<sup>2+</sup>, the surfactant surface-anchored
Cu<sup>2+</sup> is responsible for further binding of Arg, and the
electrostatic interaction between anionic surfactants and positively
charged amino acids accounts for the selective responses to Arg