Nanotextured superhydrophobic electrodes enable detection of attomolar-scale DNA concentration within a droplet by non-faradaic impedance spectroscopy.
Nanotextured superhydrophobic electrodes enable detection of attomolar-scale DNA concentration within a droplet by non-faradaic impedance spectroscopy.
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DOI：
10.1039/c3lc50517k
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发表时间：
2013-11-07
期刊：
影响因子：
6.1
通讯作者：
Alam MA
中科院分区：
文献类型：
--
作者：
Ebrahimi A;Dak P;Salm E;Dash S;Garimella SV;Bashir R;Alam MA
在微升体积的高度稀释溶液（亚飞摩尔）中的生物分子的无标记快速检测对于医疗诊断、食品安全和国土安全的化学生物传感中的许多应用至关重要。在超低浓度下，无论检测方法的灵敏度如何，传感器响应时间都受到分子朝向传感器表面的物理扩散的限制。我们已经开发了一种快速、低成本、非法拉第阻抗传感方法，用于在阿托摩尔水平下检测DI水中的合成DNA分子，该方法通过在纳米纹理超疏水电极阵列上蒸发微升DNA液滴来克服扩散极限。利用连续监测作为蒸发时间的函数的单个液滴的阻抗来显著提高检测的灵敏度和鲁棒性。电极表面上的纳米结构的形成不仅增加了表面疏水性，而且还允许液滴接触区域到传感器表面的稳健钉扎。这两个特性对于在液滴蒸发时执行高度稳定的阻抗测量至关重要。使用该方案，传统的非法拉第方法的检测限提高了五个数量级。所提出的平台代表了实现超灵敏的实验室芯片生物分子检测器的真实的时间点护理应用的一步。然而，还需要进一步的工作，以最终实现所提出的方法的全部潜力，以评价在复杂的缓冲溶液，而不是去离子水的生物样品。
Label-free, rapid detection of biomolecules in microliter volumes of highly diluted solutions (sub-femtomolar) is of essential importance for numerous applications in medical diagnostics, food safety, and chem-bio sensing for homeland security. At ultra-low concentrations, regardless of the sensitivity of the detection approach, the sensor response time is limited by physical diffusion of molecules towards the sensor surface. We have developed a fast, low cost, non-faradaic impedance sensing method for detection of synthetic DNA molecules in DI water at attomolar levels by beating the diffusion limit through evaporation of a micro-liter droplet of DNA on a nanotextured superhydrophobic electrode array. Continuous monitoring of the impedance of individual droplets as a function of evaporation time is exploited to dramatically improve the sensitivity and robustness of detection. Formation of the nanostructures on the electrode surface not only increases the surface hydrophobicity, but also allows robust pinning of the droplet contact area to the sensor surface. These two features are critical for performing highly stable impedance measurements as the droplet evaporates. Using this scheme, the detection limit of conventional non-faradaic methods is improved by five orders of magnitude. The proposed platform represents a step-forward towards realization of ultra-sensitive lab-on-chip biomolecule detectors for real time point-of-care application. Further works are however needed to ultimately realize the full potential of the proposed approach to appraise biological samples in complex buffer solutions rather than DI water.
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影响因子：
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