基于荧光探针噻唑橙与核酸适体构象变化的钾离子检测

Detection of Potassium Ion Based on Conformational Change of Aptamer and Fluorescent Probe Thiazole Orange

建立了一种基于核酸适体（Aptamer）构象效应和荧光探针噻唑橙（TO）为荧光分子开关进行钾离子检测的光学方法。室温下钾离子可与Aptamer结合形成G-四面体结构，使双链解链变为四面体结构和单链，从而导致TO荧光强度降低。考察了TO浓度、反应温度及反应时间的影响。在最佳实验条件下，钾离子浓度在1．0×10^-6-2．0×10^-4mol／L范围内与荧光强度降低比率（IF^0-IF）／IF^0呈良好的线性关系，检出限达3．3×10^-7mol／L；对Li^＋、Na^＋、Ca^2＋、Mg^2＋、NH4^＋离子进行对照实验的结果表明，该方法不仅具有较好的灵敏度和选择性，且无需荧光标记，操作简单、成本低。将该方法用于药品中钾离子含量的测定，其结果与原子吸收法一致。

An optical method for the detection of potassium ion based on the conformational change of aptamer and fluorescent probe thiazole orange （TO） was reported. Anti-K^＋ aptamer was hybridized with its complementary strand which has a single base mutation and is shorter than aptamer. TO exhibited stronger fluorescence when it interacted with the double-strand DNA mentioned above. The fluorescence emission intensity of TO decreased when double-strand DNA was dehybridized due to the formation of G-quadruplex structure and single strand DNA in the presence of K^＋. The influences of TO concentration, temperature and time on the sensing of K ^＋ were investigated. Under the optimum reaction conditions, a good linear relationship was found between the fluorescence decreasing ratio （IF^0 -IF）IF^0 and the potassium ion concentration in the range of 1.0×10^-2. 0×10^-4 mol/L, and a sensitive detection limit of 3.3 ×10^-7 mol/L was obtained. Contrast experiments with other ions such as Li^＋ , Na^＋ , Ca^2＋ , Mg^2＋ and NH4 showed that this method was label-free, simple and economical, and could be used for the determination of K ^＋ in potassium penicillin-V tablets with good sensitivity and specificity for K ^＋. The results obtained by this method were in agreement with those from atomic absorption spectrophotomertic analysis.