Copper Ion-Selective Fluorescent Sensor Based on the Inner Filter Effect Using a Spiropyran Derivative

Abstract

A highly selective copper(II) ion fluorescent sensor has been designed based on the UV-visible absorption of a spiropyran derivative coupled with the use of a metal porphyrin operative on the fluorescence inner filter effect. Spiropyrans, which combine the characteristics of metal binding and signal transduction, have been widely utilized in cationic ion recognition by UV-visible spectroscopy. In the present work, the viability of converting the absorption signal of the spiropyran molecule into a fluorescence signal was explored. On account of overlap of the absorption band of the spiropyran (lambda(abs) = 547 nm) in the presence of copper ion with the Q-band of an added fluorophore, zinc meso-tetraphenylporphyrin (lambda(abs) = 556 nm), the effective light absorbed by the porphyrin and concomitantly the emitted light intensity vary as a result of varying absorption of the spiropyran via fluorescence inner filter effect. The metal binding characteristic of the spiropyran presents an excellent selectivity for copper ion in comparison with several other heavy or transition metal ions. Since the changes in the absorbance of the absorber translate into exponential changes in fluorescence of the fluorophore, the novelty of the present device is that the analytical signal is more sensitive over that of the absorptiometry or that of the fluorometry using one single dye. To realize a practical fluorescent sensor, both the absorber and fluorophore were immobilized in a plasticized poly(vinyl chloride) membrane, and the sensing characteristics of the membrane for copper ion were investigated. The sensor is useful for measuring Cu2+ at concentrations ranging from 7.5 x 10(-7) to 3.6 x 10(-5) M with a detection limit of 1.5 x 10(-7) M. The sensor is chemically reversible, the fluorescence was switched off by immersing the membrane in copper ion solution and switched on by washing it with EDTA solution.

Chemo/bio-sensor networks

“…This ion complexation is only manifested at relatively high Co 2+ concentrations (10 -3 M or higher in acetonitrile), which is much higher than required for practical devices targeting metal ions. Consequently, there is a need for further elaboration of the binding site, in order to strengthen the ion-binding properties [11] …”

Design and Synthetic Scheme of Water Dispersible Graphene Oxide-Coumarin Complex for Ultra-Sensitive Fluorescence Based Detection of Copper (Cu2+) Ion in Aqueous Environment

“…Several studies have reported detection of Cu 2+ in micro molar concentration in biological systems using fluorescent dyes [12]- [25] and fluorescent proteins [26] [27]. Weida Wang et al used a fluorescent dye (2,4,6-trihydroxyphenylsquaraine) [20] as sensing probe to detect Cu ions.…”

Autofluorescent Hyperbranched Poly(amide amine) as Effective Fluorescent Probe for Label-free Detection of Copper(II) Ions

“…As shown in Scheme 1, Cu 2+ ions could bind to the amino groups of the HPAMAM to form cupric amine complexes, resulting in the fluorescence intensity of HPAMAM quenching by the inner filter effect, 31 caused by the absorption of the excitation and/or emission light by absorbers in the detection system. [32][33][34] Based on this, we designed a label-free, rapid, selective and sensitive fluorometric method to detect Cu 2+ ions in aqueous media by using HPAMAM. Furthermore, the practicality of this novel method based on the HPAMAM probe to detect Cu 2+ ions in real water samples also proved successful.…”