Matos Marvi A, White Lee R, Tilton Robert D
Center for Complex Fluids Engineering, Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, United States.
Colloids Surf B Biointerfaces. 2008 Feb 15;61(2):262-9. doi: 10.1016/j.colsurfb.2007.08.013. Epub 2007 Sep 4.
Many biosensors, including those based on sensing agents immobilized inside hydrogels, suffer from slow response dynamics due to mass transfer limitations. Here we present an internal pumping strategy to promote convective mixing inside crosslinked polymer gels. This is envisioned as a potential tool to enhance biosensor response dynamics. The method is based on electroosmotic flows driven by non-uniform, oscillating electric fields applied across a polyacrylamide gel that has been doped with charged colloidal silica inclusions. Evidence for enhanced mixing was obtained from florescence recovery after photobleaching (FRAP) measurements with fluorescein tracer dyes dissolved in the gel. Mixing rates in silica-laden gels under the action of the applied electric fields were more than an order of magnitude faster than either diffusion or electrophoretically driven mixing in gels that did not contain silica. The mixing enhancement was due in comparable parts to the electroosmotic pumping and to the increase in gel swelling caused by the presence of the silica inclusions. The latter had the effect of increasing tracer mobility in the silica-laden gels.
许多生物传感器，包括那些基于固定在水凝胶内部的传感剂的传感器，由于传质限制而存在响应动力学缓慢的问题。在此，我们提出一种内部泵送策略，以促进交联聚合物凝胶内部的对流混合。这被设想为增强生物传感器响应动力学的一种潜在工具。该方法基于在掺杂有带电胶体二氧化硅内含物的聚丙烯酰胺凝胶上施加不均匀、振荡电场驱动的电渗流。通过使用溶解在凝胶中的荧光素示踪染料进行光漂白后的荧光恢复（FRAP）测量，获得了混合增强的证据。在施加电场作用下，含二氧化硅凝胶中的混合速率比不含二氧化硅的凝胶中通过扩散或电泳驱动的混合速率快一个多数量级。混合增强在相当程度上归因于电渗泵送以及二氧化硅内含物的存在导致的凝胶溶胀增加。后者具有增加含二氧化硅凝胶中示踪剂迁移率的作用。
