基于聚腺嘌呤单链DNA-金纳米簇的荧光法高灵敏快速检测汞离子

聚腺嘌呤-金纳米簇（聚A-AuNCs）制备简单，快速，且具有优良的荧光性能和光学稳定性。基于聚A单链DNA为模板合成的金纳米簇，构建了一种灵敏、简单、快速的新传感方法用于检测汞离子。以柠檬酸钠为还原剂，通过水浴加热法合成金纳米簇。用荧光光谱仪和透射电镜对金纳米簇的荧光性能和微观形貌进行了表征。结果表明：合成的金纳米簇为球形，分散性良好，平均粒径约为7 nm。金纳米簇在280 nm紫外光激发下，于471 nm处发射出强烈的蓝色荧光，且金纳米簇的光学稳定性良好。溶液在4 ℃下避光保存1个月，金纳米簇的荧光强度变化很小。当汞离子存在时，汞离子与纳米金之间的高亲和力，可以有效地猝灭金纳米簇的荧光。文中讨论了反应体系中缓冲溶液pH值和反应时间对传感器性能的影响，发现缓冲溶液pH值对该方法的影响不大。汞离子对金纳米簇的荧光猝灭反应非常迅速，1 min之内就可以完成，所以后续反应仅需简单的混合即可进行荧光的测定。在最优化实验条件下，对一系列汞离子浓度进行了检测，线性方程为：y=-335.57x+541.35，检测线性范围在0.01~1 μmol·L-1之间，相关系数为0.992 6。根据空白的三倍标准偏差原则确定检测下限为3 nmol·L-1。该方法选择性好，通过9种金属离子的加入对金纳米簇的荧光信号并无明显影响，验证了金纳米簇对汞离子检测的特异性。用该方法检测了环境水样中的汞离子，加标回收率在95.33％~103.8％之间，相对标准偏差（RSD）不大于4%，可用于实际样品中Hg2+的检测。该法仅需将溶液简单混合即可实现对汞离子的检测，具有操作简便、快速、灵敏度高和选择性好等优点。

High-Sensitive and Rapid Fluorescencet Detection of Hg^2+ Based on Poly(adenine)-Templated Gold Nanoclusters

Poly adenine(Poly A)-templated gold nanoclusters(Poly A-AuNCs)have many advantages,such as facile and fastly synthesis,excellent fluorescence intensity and good photostability.Based on Poly A-AuNCs,a sensitive,simple,rapid and novel fluorescent strategy was developed for the detection of Hg^2+.AuNCs were prepared by heating-assisted methods with sodium citrate as a reductant.The AuNCs have been revealed by fluorescence spectra and transmission electron microscopy(TEM).TEM showed that the AuNCs were spherical in shape and well dispersed.The average size of AuNCs is approximately 7 nm.The fluorescence spectra showed that AuNCs emitted strong blue fluorescence with maxima fluorescence emission wavelengths at 471 nm upon excitation at 280 nm.Additionally,the AuNCs were highly stable and little fluorescence change was observed after storing at 4℃ for 1 month.In the presence of Hg^2+,the fluorescence of AuNCs was quenched effectively due to the high affinity between Hg^2+ and gold.The pH and reaction time was investigated.The fluorescence of AuNCs were insensitive to pH.The quenching reaction between Hg^2+and AuNCs was very fast and was completed within the first 1 min.Thus,the fluorescence was recorded after the simple mixture of Hg^2+and AuNCs.Under optimum conditions,a series concentration of Hg^2+was detected.The linear equation is y=-335.57x+541.35.The relative fluorescence intensity displayed a good linear relationship with Hg^2+ concentration in the range from 0.01 to 1μmol·L^-1 with the detection limit of 3 nmol·L^-1.Nine metal ions were added in the system to assess the sensing selectivity.Furthermore,the assay was successfully applied for the detection of Hg^2+ in environmental water samples with good recoveries from 95.33%~103.8%,and the relative standard deviation was lower than 4%.Thus,this novel strategy was rapid,simple and have high sensitivity and good selectivity for Hg^2+.