Neutral hydrophilic coatings for capillary electrophoresis prepared by controlled radical polymerization.
Neutral hydrophilic coatings for capillary electrophoresis prepared by controlled radical polymerization.
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DOI：
10.1016/j.aca.2016.10.023
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发表时间：
2016-12-15
影响因子：
6.2
通讯作者：
Sandoval JE
中科院分区：
文献类型：
--
作者：
Navarro FH;Gómez JE;Espinal JH;Sandoval JE
在本研究中，多孔二氧化硅颗粒以及不渗透的熔融石英晶片和毛细管改性与亲水性聚合物（羟基化聚丙烯酰胺和聚丙烯酸酯），使用基于原子转移自由基聚合（ATRP）的表面限制接枝程序，这也是表面引发的α-溴异丁酰基基团。引发剂的固定化是通过烯丙醇在氢化物硅胶上的硅氢化反应，然后用α-溴异丁酰溴酯化所得到的丙醇键合表面来实现的。元素分析，红外光谱和核磁共振光谱上的二氧化硅微粒，原子力显微镜，椭圆偏振仪和轮廓仪上的熔融石英晶片，以及CE上的熔融石英管被用来表征化学改性的二氧化硅基板在不同的阶段。我们研究了单体浓度以及交联剂对聚合物膜降低电渗透和防止蛋白质吸附（即，例如，其不结垢能力），并发现前者对这两个参数都相当不敏感。对吸附的表面失活在某种程度上更容易受到单体浓度的影响，并且似乎也受到低浓度交联剂的青睐。结果表明，ATRP在非常温和的聚合条件下，可以制备厚度可控的亲水性聚丙烯酰胺和聚丙烯酸酯涂层（水性溶剂，室温和短的反应时间），并且涂覆的毛细管表现出用于蛋白质分离的高效率（0.3-0.6百万理论塔板/米）以及在毛细管等电聚焦的固有苛刻条件下的长期水解稳定性。此外，如碱性酶的完全回收所示，在涂覆的表面上没有溶菌酶的吸附。此外，由于聚合局限于内毛细管表面，因此简单的预防措施（例如，溶液过滤）足以防止毛细管堵塞。
In the present study, porous silica particles as well as impervious fused-silica wafers and capillary tubes were modified with hydrophilic polymers (hydroxylated polyacrylamides and polyacrylates), using a surface-confined grafting procedure based on atom transfer radical polymerization (ATRP) which was also surface-initiated from α-bromoisobutyryl groups. Initiator immobilization was achieved by hydrosilylation of allyl alcohol on hydride silica followed by esterification of the resulting propanol-bonded surface with α-bromoisobutyryl bromide. Elemental analysis, IR and NMR spectroscopies on silica micro-particles, atomic force microscopy, ellipsometry and profilometry on fused-silica wafers, as well as CE on fused-silica tubes were used to characterize the chemically modified silica substrate at different stages. We studied the effect of monomer concentration as well as cross-linker on the ability of the polymer film to reduce electroosmosis and to prevent protein adsorption (i. e., its non-fouling capabilities) and found that the former was rather insensitive to both parameters. Surface deactivation towards adsorption was somewhat more susceptible to monomer concentration and appeared also to be favored by a low concentration of the cross-linker. The results show that hydrophilic polyacrylamide and polyacrylate coatings of controlled thickness can be prepared by ATRP under very mild polymerization conditions (aqueous solvent, room temperature and short reaction times) and that the coated capillary tubes exhibit high efficiencies for protein separations (0.3–0.6 million theoretical plates per meter) as well as long-term hydrolytic stability under the inherently harsh conditions of capillary isoelectric focusing. Additionally, there was no adsorption of lysozyme on the coated surface as indicated by a complete recovery of the basic enzyme. Furthermore, since polymerization is confined to the inner capillary surface, simple precautions (e.g., solution filtration) during the surface modification process are sufficient to prevent capillary clogging.