Modifying surface charge density of thermoplastic nanofluidic biosensors by multivalent cations within the slip plane of the electric double layer.
Modifying surface charge density of thermoplastic nanofluidic biosensors by multivalent cations within the slip plane of the electric double layer.
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DOI：
10.1016/j.colsurfa.2022.129147
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发表时间：
2022-05
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影响因子：
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通讯作者：
Zheng Jia;Junseo Choi;Sunggun Lee;S. Soper;Sunggook Park
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作者：
Zheng Jia;Junseo Choi;Sunggun Lee;S. Soper;Sunggook Park
热塑性纳米流体装置由于其大规模制造能力而成为用于感测单个生物分子的有前途的平台。当分子通过纳米流体网络电动驱动时，表面电荷在分子捕获和运输中起重要作用，特别是当双电层的厚度接近器件中纳米结构的尺寸时。在这里，我们使用多价阳离子来改变热塑性纳米流体装置的表面电荷密度。通过用多价离子溶液填充装置，然后取出溶液并用KCl代替以进行电导测量来进行表面电荷改变。系统研究了含Mg ~（2+）和Al ~（3+）离子溶液对聚乙二醇二丙烯酸酯（PEGDA）、聚甲基丙烯酸甲酯（PMMA）和环烯烃共聚物（COC）纳米通道的影响。总的来说，多价阳离子内的滑移面降低了装置表面的有效表面电荷密度，并且降低速率随着阳离子价态、阳离子浓度和热塑性基底的表面电荷密度而增加。我们证明了在COC中形成的直径为10 nm的面内纳米孔允许λ-DNA分子在Al 3+修饰后移位，这归因于通过降低表面电荷密度而降低的纳米孔中的粘性阻力。这项工作提供了一个通用的方法来操纵纳米流体器件的表面电荷密度的生物分子电阻脉冲传感。此外，实验结果支持离子-离子的相关性作为起源的电荷反转超过特定的化学吸附。
Thermoplastic nanofluidic devices are promising platforms for sensing single biomolecules due to their mass fabrication capability. When the molecules are driven electrokinetically through nanofluidic networks, surface charges play a significant role in the molecular capture and transportation, especially when the thickness of the electrical double layer is close to the dimensions of the nanostructures in the device. Here, we used multivalent cations to alter the surface charge density of thermoplastic nanofluidic devices. The surface charge alteration was done by filling the device with a multivalent ionic solution, followed by withdrawal of the solution and replacing it with KCl for conductance measurement. A systematic study was performed using ionic solutions containing Mg2+and Al3+for nanochannels made of three polymers: poly(ethylene glycol) diacrylate (PEGDA), poly(methyl methacrylate) (PMMA) and cyclic olefin copolymer (COC). Overall, multivalent cations within the slip plane decreased the effective surface charge density of the device surface and the reduction rate increased with the cation valency, cation concentration and the surface charge density of thermoplastic substrates. We demonstrated that a 10-nm diameter in-plane nanopore formed in COC allowed translocation of λ-DNA molecules after Al3+modification, which is attributed to the deceased viscous drag force in the nanopore by the decreased surface charge density. This work provides a general method to manipulate surface charge density of nanofluidic devices for biomolecule resistive pulse sensing. Additionally, the experimental results support ion-ion correlations as the origin of charge inversion over specific chemical adsorption.