非标记脱氧核酶构象改变荧光法检测铀酰离子

摘要

In MES buffer soIution of pH 5 . 5 ,SG can interact with uranyI specific deoxyribozymes through both intercaIation and minor groove binding,resuIting in fIuorescence enhancement in the absence of UO2 2+. The presence of UO2 2+ causes cataIytic cIeavage of the DNA substrate strand at the rA position and reIease of the ssDNA. This Ieads to the reduction of the interaction of ssDNA with SG,causing a de-crease of the fIuorescence intensity of the assay system. The decreased fIuorescence intensity was propor-tionaI to the concentration of uranyI over the range of 1. 73 × 10 -9 ~4. 40 × 10 -8 moI/L,and the Iinear regression equation wasΔF﹦108. 99C( × 10 -8 moI/L)+79. 22 with a correIation coefficient of 0. 990. The Iimit of detection( LOD)was 5. 2 × 10 -10 moI/L. The proposed method was simpIe,seIective and sensitive.%在pH 5.5 MES缓冲溶液中，当体系中不存在铀酰离子时，SYBR GreenⅠ（SG）能通过嵌入和小沟结合方式与脱氧核酶作用，导致荧光增强；当铀酰离子存在时，脱氧核酶的rA碱基处断裂，游离出单链，此时SG与单链DNA作用减弱，荧光信号降低，且体系的荧光强度变化值与铀酰离子浓度在1.73×10-9~4.40×10-8 moI/L范围内呈良好线性关系，线性回归方程为ΔF﹦108.99C（×10-8 moI/L）+79.22，相关系数r﹦0.990。根据空白管的标准偏差Sb 和标准曲线的斜率k算出LOD为5.2 × 10-10 moI/L。该方法简便、选择性好、灵敏度高。