基于DNA电化学发光传感器研究金纳米颗粒对量子点的电化学发光影响

纳米金颗粒具有高的消光系数和良好的表面等离子体共振特性, 其等离子体共振特性受纳米金颗粒的尺寸和周围环境等因素的影响. 本文基于半导体纳米晶电化学发光信号对金纳米颗粒的距离依赖性制备了DNA电化学发光传感器. 首先利用循环伏安法(CV)在玻碳电极(GCE)表面原位沉积金纳米颗粒(AuNPs), 巯基丙酸包裹的CdS量子点(QDs)与氨基修饰的双链DNA (dsDNA)通过酰胺键缩合, 形成量子点修饰的双链DNA(QDs-dsDNA). 最后将QDs-dsDNA 通过dsDNA 另一端的巯基组装到纳米金表面, 得到CdS QDs-DNA/AuNPs/GCE电化学发光传感器. 在优化电极表面QDs-dsDNA密度、金纳米颗粒沉积方法等实验条件的基础上, 对不同传感器的表面性质进行了表征, 如形貌和电化学阻抗等. 进一步通过控制纳米金和CdS QDs之间的DNA研究了纳米金对CdS QDs发光信号的影响作用. 结果显示DNA链的长度和类型对发光信号有着重要的影响. 最后将此传感器用于环境污染物的DNA损伤检测, 显示出很好的灵敏响应.

Effects of Gold Nanoparticles on Quantum Dot Electrochemiluminescence Obtained Using a DNA Electrochemiluminescence Sensor

Gold nanoparticles (AuNPs) have a high extinction coefficient and a strong surface plasmon resonance, the latter of which is influenced by the size of AuNPs and the surrounding environment. In this article, a DNA electrochemiluminescence (ECL) sensor was fabricated based on the distance-dependence of semiconductor nanocrystals' ECL signal to AuNPs. AuNPs were first deposited on the surface of glassy carbon electrode (GCE) by cyclic voltammetry (CV). The mercaptopropionic acid-capped CdS quantum dots (QDs) used in this study can covalently bind with amino-terminated double-stranded DNA (dsDNA), via the ―CO―NH bond to obtain a QDs-dsDNA compound. The QDs-dsDNA compounds were assembled on the surface of AuNPs via an Au―S bond, using the other distal of dsDNA that is labeled with thiol, to create the CdS QDs-DNA/AuNPs/GCE ECL sensor. Experimental conditions, such as the QDs-dsDNA density on the surface of electrode and the deposition method of AuNPs, were then optimized. The surface properties of different modified electrodes were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), and electrochemical impedance spectroscopy (EIS). The effect of AuNPs on the ECL intensity of CdS QDs was investigated by controlling the DNA which lies between the AuNPs and the CdS QDs. The ECL signal was affected significantly by the length and type of DNA strands. The sensor was used to detect DNA damage from environmental pollutants and exhibited a highly sensitive response.