基于脱氧核酶的水中铀酰离子荧光检测方法研究

为了实现对于水中铀酰离子的快速灵敏检测,本研究基于脱氧核酶(DNAzyme)对铀酰离子的高特异识别能力及荧光共振能量转移(FRET)的信号产生原理,建立了铀酰离子的荧光检测方法.结果发现,在铀酰离子存在的条件下,两端分别标记荧光基团和淬灭基团的底物链被标记淬灭基团的酶链特异性切断,释放标记荧光基团的底物链片段,使得体系的荧光信号强度得到提高.通过底物链与酶链的比例、浓度及反应时间的优化,提高了检测方法的灵敏性,结果显示,本方法对于铀酰离子的检测限可达到0.7 nmol·L~(-1)(3S/N),并在4~20 nmol·L~(-1)之间保持良好的线性检测范围,整个检测过程仅需6 min即可完成.本检测方法具有良好的选择性,常见的金属离子铜、铅、汞、砷、镁、钙等对于检测结果无明显干扰作用.对清华大学饮用水及自来水的加标回收率实验结果显示,加标回收率分别为98.0%~107.8%和90.0%~108.0%.本研究为今后铀酰离子在实际环境水体中的检测奠定了基础.

DNAzyme-based fluorescent detection of uranyl ion in water samples

In this study we developed a fluorescent method for the rapid detection of uranyl ion in water samples. The method realized the specific and highly efficient recognition of uranyl ion by using an engineered uranyl ion-specific DNAzyme, where a fluorescent resonance energy transfer (FRET)-based assay was designed to achieve the signal transduction. The fluorophore and quencher double labeled substrate strand was specifically cleaved by the quencher labeled DNAzyme in the presence of uranyl ion, leading to the release of the fluorophore labeled substrate fragment and thus the monotonically increased fluorescence intensity. After optimization of the ratio and concentration of the substrate strand and the DNAzyme and the reaction time, a detection limit at 0.7 nmol·L^-1(3S/N) and a dynamic range from 4 to 20 nmol·L^-1 were achieved. The whole detection process was completed within 6 min. Common metal ions such as copper, lead, mercury, arsenic, magnesium, and calcium ion, show no obvious interference for the detection of uranyl ions, suggesting that the method has a good selectivity. The method also worked well for the detection of uranyl ions spiked in both the groundwater and the drinking water in Tsinghua University with the recoveries of 98.0%~107.8% and 90.0%~108.0%, respectively. This study lays the ground work for the future detection of uranyl ion in the environmental water.