Ebara Mitsuhiro, Hoffman John M, Hoffman Allan S, Stayton Patrick S
Department of Bioengineering, University of Washington, Seattle, WA 98195, USA.
Lab Chip. 2006 Jul;6(7):843-8. doi: 10.1039/b515128g. Epub 2006 May 5.
We report here a reversible microchannel surface capture system for stimuli-responsive grafted bioanalytical beads. Poly(N-isopropylacrylamide) (PNIPAAm) was grafted onto polydimethylsiloxane (PDMS) surfaces by a UV-mediated graft polymerization from a photoinitiator that was preadsorbed in the channel wall. The surface grafting density and resulting switchable hydrophilic/hydrophobic properties were controlled by varying the photo-illumination times and/or the initiator concentration. At limiting PNIPAAm-graft densities, the surfaces demonstrated minimal contact angles of 35 degrees below the lower critical solution temperature (LCST) and maximal contact angles of 82 degrees above it. These contact angles could be varied depending on the graft density. The surface grafts are spatially limited to the photo-illuminated region to define where the trap is constructed. The surface traps capture PNIPAAm-grafted nanobeads uniformly above the LCST and facilitate their rapid release as the temperature is reversed to below the LCST. This dual surface trap and injectable chromatography system could be useful in many applications, such as affinity separations, immunoassays, and enzyme bioprocesses, by providing for the controlled capture and release of chromatography beads.
我们在此报告一种用于刺激响应性接枝生物分析珠的可逆微通道表面捕获系统。通过紫外线介导的接枝聚合反应，将聚（N-异丙基丙烯酰胺）（PNIPAAm）从预先吸附在通道壁上的光引发剂接枝到聚二甲基硅氧烷（PDMS）表面。通过改变光照时间和/或引发剂浓度来控制表面接枝密度以及由此产生的可切换的亲水/疏水性质。在极限PNIPAAm接枝密度下，表面在低于下临界溶液温度（LCST）时表现出最小接触角为35度，在高于该温度时表现出最大接触角为82度。这些接触角可根据接枝密度而变化。表面接枝在空间上局限于光照区域，以确定捕获区域的位置。表面捕获区域在LCST以上均匀捕获PNIPAAm接枝的纳米珠，并在温度逆转至低于LCST时促进其快速释放。这种双表面捕获和可注射色谱系统通过实现对色谱珠的可控捕获和释放，可用于许多应用，如亲和分离、免疫测定和酶生物过程。
