基于 G-四联体门控制效应的铅离子适配体传感器

将富鸟嘌呤(G)序列核酸适配体与门控制效应相结合,通过控制门的开关实现信号放大,构建了新型电化学生物传感器,用于铅离子(Pb2+)的高灵敏检测。首先将单-6-巯基-β-环糊精(6-SH-β-CD)自组装在金电极上,形成有序排列的分子自组装膜,且分子之间留有空隙,可作为探针通过的门结构。随后将发夹结构的富含 G 序列的核酸适配体修饰在环糊精次面端口,制得可特异性识别 Pb2+的电化学生物传感器。富 G 序列适配体结合 Pb2+后可折叠形成 G-四联体结构(G4-Pb2+),覆盖住电极表面的探针通道,产生关门效应,使探针氧化还原电流强度减小,进而形成门控制效应,利用该效应可进行 Pb2+的定量检测。门控制效应显著提高了信噪比和检测的灵敏度,在1×10-13~5×10-11 mol/ L 浓度范围内,Pb2+浓度的负对数与 DPV 响应电流呈良好的线性关系,检出限为3.6×10-14 mol/ L(DL=3δb / K)。传感器用于实际水样品中 Pb2+的测定,结果令人满意。

Electrochemical Lead Ion Aptasensor Based on G-Quadruplex and Gate-controlled Signal Amplification

A new strategy for constructing electrochemical aptasensor for lead ion ( Pb2+ ) analysis with extremely high sensitivity was proposed based on the formation of G-quadruplex (G4) when Pb2+ reacting with G-rich aptamers, and the gate-controlled effect was achieved through the controllable channels of probe. SH-β-cyclodextrins were firstly self-assembled on the surface of gold electrode to form an ordered monomolecular layer containing interspaces among β-CD units. When the G-rich aptamer was linked to the self-assembledβ-CD and the sensor was immersed into the Pb2+ solution, the aptamers would combine with Pb2+ and then form G-quadruplex structures, which would cover the interspaces and then block the channels for probe entrance. The whole process reduced the oxidative current of probe, which provided a fundamental basis of Pb2+determination in a quantitative way. Gate-controlled effect enhanced signal-to-noise ratio as well as sensitivity simultaneously. The differential pulse voltammetry response current showed a good linear relationship with the negative logarithm of Pb2+ concentration in the range from 1×10-13 mol/ L to 5×10-11 mol/ L, with a detection limit of 3. 6×10-14 mol/ L(DL = 3δb / K). The aptasensor was successfully applied to the detection of Pb2+ in real water samples with recoveries of 97. 5% -103. 3% .