A Novel Schiff-Base Fluorescent Probe for Cr³⁺ and Its Bioimaging in Cells

Abstract

Trivalent chromium (Cr 3＋) plays an important role in the metabolismof fats, nucleic acids, carbohydrates and proteins. Moreover, Cr 3＋ is considered to be a carcinogen and is extremely harmful to humans. Therefore, Cr 3＋ fluorescent probe L was synthesized by reaction of 8-hydroxyquinolinaldehyde with thiocarbazone. The probe L showed high selectivity towards Cr 3＋ ion through the color of solution changed from colorless to yellow for naked-eye detection and significant fluorescence intensity enhanced in CH 3 CN/H 2 O (V∶V＝1∶2, Tris buffer 50 mmol/L, pH＝7.3) solution. The 1∶1 binding stoichiometry between probe and Cr 3＋ was determined from Job's plot, fluorescence titration, ESI-MS and density functional theory (DFT) calculations. The association constant (K a) and the detection limit for Cr 3＋ were found to be to be 1.00×10 5 and 2.85×10-7 mol/L, respectively. Moreover, bioimaging experiments showed that L could sense Cr 3＋ ion in living cells with a fluorescence enhancement signal. Keywords Cr 3＋ ; fluorescent probe; DFT; bioimaging 三价铬(Cr 3＋)是人体中重要的微量元素, 一般情况 下由人类和自然资源释放到环境中的过渡金属通过食 物链在人体中积累. 其中, Cr 3＋ 离子对维持有效的碳水 化合物、脂质和蛋白质的代谢起着重要的作用. 然而, Cr 3＋ 离子却被认为是一种致癌物质, 对人类的健康具有 极大的危害 [3]. 世界卫生组织(WHO)规定饮用水中 Cr 3＋ 离子的最大浓度为 50 μg/L, 正常人每天需要吸收 25～ 35 μg 的 Cr 3＋ 离子以改善葡萄糖和脂肪的代谢. 人体内

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