Integrated microfluidic devices for the purification, amplification, and detection of nucleic acids are a prevalent area of research due to their potential for miniaturization, assay integration, and increased efficiency over benchtop assays. These devices frequently contain micrometer-sized magnetic beads with a large surface area for the capture and manipulation of biological molecules such as DNA and RNA. Although magnetic beads are a standard tool for many biological assays, beads functionalized with biological molecules can adhere to microchannel walls and prevent further manipulation of the beads within the channel. Here, we analyze the effects of solution composition, microchannel hydrophobicity, and bead surface hydrophobicity on DNA-functionalized bead adhesion in a borosilicate glass microfluidic device. Bead adhesion is primarily a result of adsorption of the bead-linked DNA molecule to the microchannel wall; >81% of beads are consistently removed when not functionalized with DNA. Hydrophobicities of both the microchannel walls and the microbead surface are the primary determinants of bead adhesion, rather than electrostatic interactions and ion bridging. Surprisingly, DNA-functionalized bead adhesion in a standard RNA amplification solution was virtually eliminated by using hydrophobic microbeads with hydrophobic microchannel walls; under such conditions, 96.6 ± 1.6% of the beads were removed in one 43 nl/s, 10-min wash. The efficiency of a downstream RNA amplification reaction using DNA-functionalized beads did not appear to be affected by the hydrophobicity of the microbead surface. These findings can be applied to assays that require the efficient use of magnetic beads in DNA-based microfluidic assays.

中文翻译：

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在玻璃微流体通道中DNA功能化珠粒的吸附和解吸。

用于核酸的纯化，扩增和检测的集成微流控设备是研究的主流领域，因为它们具有微型化，检测整合和比台式检测更高的效率的潜力。这些设备通常包含具有大表面积的微米大小的磁珠，用于捕获和操纵DNA和RNA等生物分子。尽管磁珠是许多生物学测定的标准工具，但被生物分子功能化的珠子可以附着在微通道壁上，并阻止进一步操纵通道中的珠子。在这里，我们分析了溶液成分，微通道疏水性和珠表面疏水性对硼硅酸盐玻璃微流体装置中DNA功能化珠粘附的影响。珠粘附主要是珠连接的DNA分子吸附到微通道壁上的结果。如果未使用DNA进行功能化，> 81％的珠子将始终被去除。微通道壁和微珠表面的疏水性是珠附着力的主要决定因素，而不是静电相互作用和离子桥接的主要决定因素。令人惊讶的是，通过使用带有疏水微通道壁的疏水微珠，实际上消除了标准RNA扩增溶液中DNA功能化的珠的粘附；在这样的条件下，一次清洗10分钟，一次43 nl / s去除了96.6±1.6％的珠子。使用DNA功能化的珠子的下游RNA扩增反应的效率似乎不受微珠表面疏水性的影响。