中文摘要：

基于Hg2＋与胸腺嘧啶（T）形成＂T-Hg2＋-T＂结构的原理建立了一种简单、灵敏的荧光增强法检测Hg2＋的方法。两条部分互补的富含T碱基的ssDNA在常温下分别以单链状态存在。当加入Hg2＋,由于T-Hg2＋-T键的形成,两条ssDNA形成DNA双螺旋结构,溶液中荧光分子溴化乙锭（EB）嵌入DNA双螺旋结构,EB荧光强度增强。考察了DNA序列及DNA与EB浓度比等因素对检测灵敏度的影响。在优化的条件下,EB荧光强度和Hg2＋浓度在1.0×10-8～9.0×10-7 mol/L范围内呈线性关系,检出限为3.0 nmol/L。Ca2＋,Mg2＋等常见阳离子对Hg2＋的检测不产生干扰,方法具有良好的选择性。

英文摘要：

A simple and rapid fluorescence method was developed for the detection of Hg2＋ based on specific thymine T-Hg2＋-T structure and ethidium bromide（EB）.Duplex DNA with T-T mismatches was employed.Melting temperature of dsDNA is lower than room temperature since there are several T-T mismatch in dsDNA,and therefore keeps single strand in absence of Hg2＋ at room temperature.While in the presence of Hg2＋ ions,T-Hg2＋-T coordination chemistry leads to the formation of DNA duplexes.EB can intercalate into dsDNA,accompanying by enhancement of EB fluorescence.The concentrations of dsDNA and EB were optimized;detection can be finished with 1 min after addition of Hg2＋.Under the optimal conditions,the change of fluorescence was proportional to the concentration of Hg2＋ in the range of 1.0 × 10-8 to 9.0 × 10-7 mol/L and the detection limit was 3.0×10-9 mol/L.The interferences from selected inorganic ions were investigated and the sensor shows a good selectivity for Hg2＋,Ca2＋,Mg2＋ and other metal ions had no significant interferences.The proposed method was simple and selective.