Copper Ion-Selective Fluorescent Sensor Based on the Inner Filter Effect Using a Spiropyran Derivative
作者:Na Shao、Ying Zhang、SinMan Cheung、RongHua Yang、WingHong Chan、Tain Mo、KeAn Li、Feng Liu
DOI:10.1021/ac051010r
日期:2005.11.15
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 (λabs = 547 nm) in the presence of copper ion with the Q-band of an added fluorophore, zinc meso-tetraphenylporphyrin (λabs = 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 × 10-7 to 3.6 × 10-5 M with a detection limit of 1.5 × 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.
基于螺吡喃衍生物的紫外可见光吸收,并利用金属卟啉的荧光内滤光片效应,设计出了一种高选择性铜(II)离子荧光传感器。螺吡喃结合了金属结合和信号转导的特点,已被广泛用于利用紫外可见光谱识别阳离子。本研究探讨了将螺吡喃分子的吸收信号转化为荧光信号的可行性。由于铜离子存在时螺吡喃的吸收带(λabs = 547 nm)与添加的荧光团中四苯基卟啉锌的 Q 带(λabs = 556 nm)重叠,卟啉吸收的有效光和发射的光强度随之变化,这是因为螺吡喃通过荧光内滤光片效应吸收了不同的荧光。与其他几种重金属或过渡金属离子相比,螺吡喃的金属结合特性对铜离子具有极佳的选择性。由于吸收剂吸光度的变化会转化为荧光团荧光的指数变化,因此本装置的新颖之处在于其分析信号的灵敏度要高于吸收测量法或使用单一染料的荧光测量法。为了实现实用的荧光传感器,我们将吸收剂和荧光团固定在塑化聚氯乙烯膜中,并研究了该膜对铜离子的传感特性。该传感器可用于测量浓度为 7.5 × 10-7 至 3.6 × 10-5 M 的 Cu2+,检测限为 1.5 × 10-7 M。该传感器具有化学可逆性,将膜浸入铜离子溶液中可关闭荧光,用 EDTA 溶液洗涤后可开启荧光。