pH-Independent Fluorescent Chemosensor for Highly Selective Lithium Ion Sensing

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• 作者：Daniel Citterio ; Junichiro Takeda ; Masaki Kosugi ; Hideaki Hisamoto ; Shin-ichi Sasaki ; Hirokazu Komatsu ; Koji Suzuki
• 刊名：Analytical Chemistry
• 出版年：2007
• 出版时间：February 1, 2007
• 年：2007
• 卷：79
• 期：3
• 页码：1237 - 1242
• 全文大小：109K
• 年卷期：v.79,no.3(February 1, 2007)
• ISSN：1520-6882

文摘

Since lithium salts are used as pharmaceutically activecompounds against manic-depressive psychosis, there isa demand to monitor the lithium concentration in bloodin the narrow range of 0.6-1.2 mM effectively and safely.Here we report on an optical sensor approach for thedetermination of Li⁺, based on the design and synthesisof a novel lithium fluoroionophore KLI-1 and its polymerimmobilizable derivative KLI-2, and the application to anoptode. The novel lithium fluoroionophores rely on atetramethyl "blocking subunit" bearing 14-crown-4 as aLi⁺-selective binding site and 4-methylcoumarin as afluorophore, intramolecularly connected to show ICT-typewavelength shift for ratiometric fluorescence measurements. The fluoroionophores showed high selectivity forLi⁺ with binding-induced blue shift in the fluorescencespectra, no response to major biological interfering cations(K⁺, Ca²⁺, Mg²⁺), a selectivity of log k_Li+,Na+ = -2.4 overNa⁺ in solution, and no response to pH in the range ofpH 3-10. A hydrophilic optode membrane with KLI-2immobilized also showed good selectivity for Li⁺, pHindependence in the physiological range (pH 6-8), andfully reversible signal changes. KLI-1 and KLI-2 areexcellent Li⁺ fluorescent chemosensors that can be applied to quantitative measurements of lithium in clinicalsamples, although possible interference from Na⁺ has tobe considered at the lower therapeutic level of Li⁺.