基于DNA双链取代策略免标记检测铅离子的研究

摘要

建立了一种基于DNA双链取代策略和SYBR Green Ⅰ (SG)作为荧光染料插入剂进行免标记铅离子检测的荧光传感方法.SG作为一种染料分子,与单链DNA作用产生的荧光强度很弱,但可以插入双链DNA,使SG荧光强度明显增强.检测时铅离子适配体首先与其部分互补单链DNA杂交形成稳定的双链DNA结构,当溶液中存在铅离子时,铅离子与其适配体特异性结合,双链DNA的数量减少,加入SG可实现铅离子的免标记定量检测.此方法具有灵敏度高、特异性强、简便快速等优点.最低险测浓度为2 nmol/L,检出限(S/N =3)为1.6 nmol/L,实际样品检测结果良好.%A fluorescent sensor was developed for detection of lead ion based on the replacement of double-stranded DNA and the difference of fluorescent intensity of the SG between single-stranded DNA and double-stranded DNA.As a kind of dye,SG could be inserted into the double-stranded DNA,making the SG fluorescence intensity stronger.The aptamer of lead ion reacted with its complementary strand to form a stable double chain.When lead ions existed in the solution,they could specifically bind with the aptamers to reduce the amount of double-stranded DNA.The lead ions could be quantificationally detected according to the fluorescence intensity when the SG was added into the solution.With the advantages of high sensitivity,strong specificity,simpleness and rapidness,the method has the lowest detection concentration of 2 nmol/L for lead ion,and a detection limit(S/N =3) of 1.6 nmol/L.