纳米金颗粒增强信号的电化学生物传感器用于谷胱甘肽和半胱氨酸的检测

构建了一种高灵敏检测谷胱甘肽(GSH)和半胱氨酸(Cys)的新型电化学生物传感器. 先将富含T碱基的DNA1和DNA2探针分别修饰在金电极和纳米金颗粒(AuNPs)上, 再加入Hg²⁺, 通过形成T-Hg²⁺-T结构使AuNPs结合到金电极表面. 当加入GSH(或Cys)后, GSH(或Cys)可以竞争结合T-Hg²⁺-T结构中的Hg²⁺, 使AuNPs离开电极表面. 由于AuNPs上修饰的DNA探针能够静电吸附大量电活性物质六氨合钌(RuHex), 因此该过程可引起计时电量信号的显著变化, 据此实现了GSH(或Cys)的高灵敏检测. 该传感器的检出限达10 pmol/L, 比荧光法或比色法降低了2~3个数量级. 实验结果表明, 该传感器具有较好的选择性.

High Sensitive Glutathione and Cysteine Detection by Au Nanoparticles Enhanced Electrochemical Biosensor

Glutathione(GSH) and cysteine(Cys) are biological thiols that play vital roles in maintaining cellular functions. GSH is a thiol-group-containing tripep-tide, which has a pivotal role in maintaining the redu-cing environment in cells. Cys is a biomarker for various medical conditions, and a disease-associated physiological regulator. In this work, a high sensitive electrochemical biosensor for GSH and Cys detection was constructed using Au nanoparticles enhanced signal amplification. DNA1 and DNA2 were all poly-T DNA probes. Firstly, DNA1 was modified on the surface of electrode, and then DNA2 was modified on the AuNPs. In the presence of Hg²⁺, the binding of Hg²⁺ with thymine(T) was employed to form T-Hg²⁺-T structure and thus DNA2 modified AuNPs could be captured on the electrode surface. The added GSH(or Cys) could selectively coordinate with Hg²⁺ of the T-Hg²⁺-T structure, which resulted in the departure of AuNPs from the electrode surface. Since DNA modified on AuNPs could bind a large number of electric active RuHex via electrostatic interaction, the chronocoulometry signal was reduced obviously, and then GSH(or Cys) could be detected according to the change of chronocoulometry signal. The results showed that the electrochemical biosensor was highly sensitive, and it could detect as low as 10 pmol/L for GSH(or Cys). It was about 2-3 orders of magnitude lower than those of fluorescent and colorimetric methods. Moreover, eight kinds of amino acids were used as control to investigate the selectivity of this electrochemical biosensor, and the results showed that this electrochemical biosensor showed good selectivity.