Xia Ling, Deb Rajesh, Dutta Debashis
Department of Chemistry, University of Wyoming, Laramie, WY, 82071, USA.
Department of Chemistry, University of Wyoming, Laramie, WY, 82071, USA.
Anal Chim Acta. 2020 Oct 23;1135:83-90. doi: 10.1016/j.aca.2020.08.019. Epub 2020 Aug 22.
In this article, we report a simple approach to stacking micro- and nanoparticle zones by electrokinetically migrating them through moderately confined channels of uniform cross-section. Experiments show the reported pre-concentration process to initiate at the tail end of the zone following its electrokinetic injection, with the stacked region migrating faster than the rest of the sample band. This effect causes the particles traveling in front to merge into the stacked region making it grow both in size and concentration. Because the stacked zone also gradually loses particles from its trailing edge, it eventually disintegrates upon running out of particles at its front end. Nevertheless, enhancements in peak height by over 100-fold were recorded using the reported approach for polystyrene beads with diameters comparable to the channel depth. This enhancement however, exhibited a temporal variation as the particle band migrated through the analysis column reaching a maximum value that depended on the particle diameter, particle concentration, channel depth, electric field strength, electroosmotic mobility, etc. Interestingly, the peak area recorded by the detector remained relatively constant during this particle migration period allowing reliable sample quantitation. Moreover, upon incubating antibody-coated particles against an antigen sample, the peak area for the particle zone was seen to scale linearly with the antigen concentration establishing the utility of the reported focusing phenomenon for chemical/biochemical analysis. The noted stacking technique was further applied to enabling UV absorbance detection of particle zones on microchips which then allowed us to determine the colloidal content in actual natural water samples. .
在本文中，我们报告了一种通过电动迁移使微米和纳米颗粒区域在具有均匀横截面的适度受限通道中堆叠的简单方法。实验表明，所报道的预浓缩过程在区域的电动注入后于区域的尾端开始，堆叠区域的迁移速度比样品带的其余部分快。这种效应导致前方行进的颗粒合并到堆叠区域中，使其尺寸和浓度都增加。由于堆叠区域也会从其后缘逐渐失去颗粒，它最终会在前端颗粒耗尽时解体。然而，使用所报道的方法对直径与通道深度相当的聚苯乙烯珠粒进行记录时，峰高增强了100倍以上。然而，这种增强随着颗粒带迁移通过分析柱而呈现出时间变化，达到一个取决于颗粒直径、颗粒浓度、通道深度、电场强度、电渗迁移率等的最大值。有趣的是，在此颗粒迁移期间，检测器记录的峰面积保持相对恒定，从而实现可靠的样品定量。此外，在用抗体包被的颗粒与抗原样品孵育后，颗粒区域的峰面积与抗原浓度呈线性关系，确立了所报道的聚焦现象在化学/生化分析中的实用性。所提到的堆叠技术进一步应用于在微芯片上实现颗粒区域的紫外吸光度检测，这使我们能够测定实际天然水样中的胶体含量。
