构象转换型传感器对汞、铅、锶离子的同时检测

将核酸构象转换与纳米孔膜技术联用设计了一种新型高灵敏电化学传感器, 实现了对Hg ²⁺, Pb ²⁺和Sr ²⁺的分步同时检测. 使用2种分别能与Hg ²⁺及Pb ²⁺, Sr ²⁺结合的核酸适体, 将其固定在氧化铝纳米孔膜孔道内以阻碍铁氰化钾离子传导. 利用核酸适体包裹目标物时的蜷缩状态与目标物被洗脱剂洗脱后核酸适体的伸展状态之间的构象转换, 控制纳米孔通道的“开”和“关”, 使铁氰化钾溶液的氧化还原电流发生改变. 通过监测铁氰化钾溶液的电信号变化值, 可实现同时检测此3种金属离子的目的. 实验结果表明, 该传感器对3种金属离子具有很高的灵敏度和选择性, 检测的线性范围均为0.051.50 nmol/L, 对Hg ²⁺, Pb ²⁺和Sr ²⁺的检出限分别为0.013, 0.017和0.022 nmol/L(S/N=3).

Simultaneous Detection of Mercury,Lead and Strontium Ions Based on Conformational Conversion Sensor †

A high-sensitive and specific electrochemical biosensor was designed for simultaneous detection of mercury ion(Hg ²⁺), lead ion(Pb ²⁺) and strontium ion(Sr ²⁺) by oligonucleotide conformational transformation. The biosensor was based on porous anodic alumina(PAA) modified with two oligonucleotide aptamers which could capture Hg ²⁺, Pb ²⁺ and Sr ²⁺, respectively. The aptamers can block Fe(CN)₆] ^3-/4- ion conduction in the nanochannels of PAA. In the presence of Hg ²⁺, Pb ²⁺ and Sr ²⁺, the aptamers could bend and wrap around those metal ions to make the nanochannel unobstructed, and then, the redox current of Fe(CN)₆] ^3-/4- could be increased. When the biosensor eluted with β-mercaptoethanol(βME), 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid(DOTA) and kryptofix 222(KP) successively, the aptamers stretched and released Hg ²⁺, Pb ²⁺ and Sr ²⁺ in sequence, leading to the re-blockage of nanochannel with the decrease of the redox current. The calibration curves of Hg ²⁺, Pb ²⁺ and Sr ²⁺ were obtained in the range of 0.05—2.50 nmol/L, and the detection limits were 0.013, 0.017 and 0.022 nmol/L, respectively. Furthermore, the biosensor is easily constructed, stable and reusable. It is hopeful to apply in the daily monitoring of harmful metal ions in drinking water or environmental water.