Molecular Design of Light-Responsive Hydrogels, For in Situ Generation of Fast and Reversible Valves for Microfluidic Applications
作者:Jeroen ter Schiphorst、Simon Coleman、Jelle E. Stumpel、Aymen Ben Azouz、Dermot Diamond、Albertus P. H. J. Schenning
DOI:10.1021/acs.chemmater.5b01860
日期:2015.9.8
Reversible light-responsive hydrogel valves with response characteristics compatible for microfluidics have been obtained by optimization of molecular design of spiropyran photoswitches and gel composition. Self-protonating gel formulations were exploited, wherein acrylic acid was copolymerized in the hydrogel network as an internal proton donor, to achieve a swollen state of the hydrogel in water at neutral pH. Light-responsive properties were endowed upon the hydrogels by copolymerization of spiropyran chromophores, using electron withdrawing and donating groups to tune the gel-swelling and shrinkage behavior. In all cases, the shrinkage was determined by the water diffusion rate, while for the swelling the isomerization kinetics is the rate-determining step. For one hydrogel, reversible and reproducible volume changes were observed. Finally, gel-valves integrated within microfluidic channels were fabricated, allowing reversible and repeatable operation, with opening and closing of the valve in minutes.
通过优化螺吡喃光开关的分子设计和凝胶成分,获得了具有与微流体兼容的响应特性的可逆光响应水凝胶阀。利用自质子化凝胶配方,在水凝胶网络中共聚丙烯酸作为内部质子供体,从而使水凝胶在 pH 值为中性的水中处于膨胀状态。通过共聚螺吡喃发色团,赋予水凝胶光响应特性,利用电子汲取基团和电子捐赠基团调节凝胶的膨胀和收缩行为。在所有情况下,收缩都是由水扩散速率决定的,而膨胀则是由异构化动力学决定的。在一种水凝胶中,观察到了可逆和可重复的体积变化。最后,还制造出了集成在微流体通道中的凝胶阀,可在几分钟内打开和关闭阀门,实现可逆和可重复的操作。