DNA-NEMS sensor from diamond

在这个应用中，我们将在金刚石上实现和优化DNA- nems（纳米机电系统）结构，用于DNA杂交的电化学检测。电操纵单链和双链DNA的不同动力学行为将被用作传感器原理。DNA标记分子将被氧化还原标记并共价键合到金刚石工作电极上。反电极将是一个钻石扫描电化学显微镜（SECM）尖端，它是扫描探针显微镜的一部分，可以以纳米精度放置以优化几何形状。目标DNA将是无标签的。为了产生氧化还原电流，DNA将暴露在交流电场中，其中氧化还原标签在工作电极和反电极之间移动。傅立叶变换锁相检测将用于监测氧化还原电流的幅度和相位。这些实验将在微到纳米电极上进行，电极直径从200微米（微电极）到200纳米（纳米电极），在不同盐浓度（3毫米到1000毫米）的电解质溶液中进行。由于从ss-链到ds-链DNA分子的灵活性变化，电流振幅和相位的变化将被详细表征。传感器区域将小型化，目标是达到最高的灵敏度、再现性和快速传感。ss-和ds- dna的不同动力学行为将被详细表征，并从a)频率响应，b)电场响应和c)振荡高度幅值的变化中推导出ss/ds区分参数。

In this application we will realize and optimize DNA-NEMS (Nano-Electro-Mechanical-Systems) structures on diamond for electrochemical detection of DNA hybridization. The dissimilar kinetic behavior of electrically manipulated single and double-stranded DNA will be applied as sensor principle. The DNA marker molecules will be redox-labeled and covalently bonded to a diamond working electrode. The counter electrode will be a Diamond Scanning Electro-Chemical Microscopy (SECM) Tip which is part of a scanning probe microscope and which can be place with nano-meter accuracy to optimize the geometry. The target DNA will be label free. To cause a redox current, the DNA will be exposed to ac electric fields where the redox label is moving between working and counter electrodes. Fourier-transform lock-in detection will be applied to monitor the redox current amplitude and phase. These experiments will be performed on micro- to nano-electrodes with electrode diameters ranging from 200 micrometer (micro-electrode) to 200 nm (nano-electrode) in electrolyte solutions with varying salt concentrations (3 mM to 1000 mM). Due to a change of flexibility from ss- to ds-stranded DNA molecules the variation of current amplitude and phase will be characterized in detail. The sensor area will be miniaturized with the goal to reach highest sensitivity, reproducibility and fast sensing. The dissimilar kinetic behavior of ss- and ds-DNA will be characterized in detail to deduce the ss/ds discrimination parameters from a) frequency response, b) electric field response and c) variations in oscillating height amplitudes.