Sung Wang-Chou, Chen Huang-Han, Makamba Honest, Chen Shu-Hui
Department of Chemistry, National Cheng Kung University, No. 1, College Road, Tainan 701, Taiwan.
Anal Chem. 2009 Oct 1;81(19):7967-73. doi: 10.1021/ac901138w.
Integration of a hydrogel and polydimethylsiloxane (PDMS)-based microfluidic device can greatly reduce the cost of developing channel-based devices. However, there are technical difficulties including the hydrophobic and inert surface properties associated with PDMS as well as back pressure and fragile material associated with the use of hydrogel in microchannels. In this study, a strategy to covalently photopattern 3-D hydrogel plugs with functionalized protein G inside microfluidic channels on a hydrophilic PDMS substrate coated with polyelectrolyte multilayers (PEMS) is presented. In this process, a UV-light microscope is applied to initiate the protein G-poly(acryl amide) copolymerization from the bulk substrate to solution areas via the deeply implanted photoinitiator (PI), resulting in sturdy 3D plugs covalently bonded to the upper and lower channel wall, while leaving open spaces in the channel width for the fluid to flow through. In addition, the long-term hydrophilicity and low nonspecific binding property associated with PEMS surface can be conserved for the nonpatterned area, leading to hydrogel plugs in extremely hydrophilic and permeable environment in a restricted channel space for bubble-free fluid transport and affinity interaction. By immobilization of well-oriented antibodies via protein G on the hydrogel plugs in the channel, estrogen receptor alpha (ERalpha) is demonstrated to be captured quantitatively with high loading capacity and high specificity.
水凝胶与基于聚二甲基硅氧烷（PDMS）的微流控装置的集成可以大大降低开发基于通道的装置的成本。然而，存在一些技术难题，包括与PDMS相关的疏水和惰性表面特性，以及与在微通道中使用水凝胶相关的背压和易碎材料。在本研究中，提出了一种在涂覆有聚电解质多层膜（PEMS）的亲水性PDMS基板上的微流控通道内，用功能化蛋白G对三维水凝胶塞进行共价光图案化的策略。在此过程中，应用紫外光显微镜通过深度植入的光引发剂（PI）引发蛋白G-聚（丙烯酰胺）从本体基质到溶液区域的共聚反应，从而形成牢固地共价结合到通道上下壁的三维塞子，同时在通道宽度上留出开放空间供流体流过。此外，与PEMS表面相关的长期亲水性和低非特异性结合特性可以在未图案化区域得以保留，从而在受限的通道空间中形成处于极亲水和可渗透环境的水凝胶塞，以实现无气泡流体传输和亲和相互作用。通过经由蛋白G将取向良好的抗体固定在通道内的水凝胶塞上，雌激素受体α（ERα）被证明能够以高负载能力和高特异性进行定量捕获。
