Shin Il Hyung, Kim Ki-Jung, Kim Jiman, Kim Hee Chan, Chun Honggu
Department of Biomedical Engineering, Seoul National University, 28 Yongon-dong, Chongno-gu, Seoul, South Korea.
Lab Chip. 2014 Jun 7;14(11):1811-5. doi: 10.1039/c4lc00024b. Epub 2014 Apr 15.
A cation-selective microfluidic sample preconcentration system is described. The cation sample was electropreconcentrated using a reversed-direction electroosmotic flow (EOF) and an anion-permselective filter, where an electric double layer (EDL) overlap condition existed. The anion-permselective filter between microchannels was fabricated by three different methods: 1) extending a positively charged, nanoporous, polymer membrane by photopolymerization of poly(diallyldimethylammonium chloride) (PDADMAC); 2) etching a nanochannel and then coating it with a positively-charged monomer, N-[3-(trimethoxysilyl)propyl]-N'-(4-vinylbenzyl)ethylenediamine hydrochloride (TMSVE); and, 3) etching a nanochannel and then coating it with a positively-charged, pre-formed polymer, polyE-323. The EOF direction in the microchannel was reversed by both TMSVE and polyE-323 coatings. The cation-selective preconcentration was investigated using charged fluorescent dyes and tetramethylrhodamine isothiocyanate (TRITC)-tagged peptides/proteins. The preconcentration in the three different systems was compared with respect to efficiency, dependence on buffer concentration and pH, tolerable flow rate, and sample adsorption. Both TMSVE- and polyE-323-coated nanochannels showed robust preconcentration at high flow rates, whereas the PDADMAC membrane maintained anion-permselectivity at higher buffer concentrations. The TMSVE-coated nanochannels showed a more stable preconcentration process, whereas the polyE-323-coated nanochannels showed a lower peptide sample adsorption and robust efficiency under a wide range of buffer pHs. The system described here can potentially be used for the preconcentration of cationic peptides/proteins on microfluidic devices for subsequent analyses.
本文描述了一种阳离子选择性微流控样品预浓缩系统。阳离子样品利用反向电渗流（EOF）和阴离子选择透过性滤膜进行电预浓缩，其中存在双电层（EDL）重叠条件。微通道之间的阴离子选择透过性滤膜通过三种不同方法制备：1）通过聚二烯丙基二甲基氯化铵（PDADMAC）的光聚合扩展带正电的纳米多孔聚合物膜；2）蚀刻纳米通道，然后用带正电的单体N-[3-(三甲氧基甲硅烷基)丙基]-N'-(4-乙烯基苄基)乙二胺盐酸盐（TMSVE）进行涂层；3）蚀刻纳米通道，然后用带正电的预成型聚合物聚E-323进行涂层。TMSVE和聚E-323涂层均可使微通道中的EOF方向反转。使用带电荷的荧光染料和异硫氰酸四甲基罗丹明（TRITC）标记的肽/蛋白质对阳离子选择性预浓缩进行了研究。比较了三种不同系统在预浓缩效率、对缓冲液浓度和pH的依赖性、可耐受流速以及样品吸附方面的情况。TMSVE涂层和聚E-323涂层的纳米通道在高流速下均表现出强大的预浓缩能力，而PDADMAC膜在较高缓冲液浓度下保持阴离子选择透过性。TMSVE涂层的纳米通道表现出更稳定的预浓缩过程，而聚E-323涂层的纳米通道在广泛的缓冲液pH范围内表现出较低的肽样品吸附和强大的效率。本文所述系统可潜在地用于微流控装置上阳离子肽/蛋白质的预浓缩，以便进行后续分析。
