Department of Chemistry , University of Alberta , Edmonton , Alberta T6G 2G2 , Canada.
ACS Appl Mater Interfaces. 2018 Apr 18;10(15):13124-13129. doi: 10.1021/acsami.8b04053. Epub 2018 Apr 5.
A monolithic layer of poly( N-isopropylacrylamide- co-acrylic acid) microgels was deposited on an Au electrode and used for electrically triggered release of the small molecule crystal violet (CV), which was used as a model drug. CV was loaded into the surface-bound microgels by exposing them to a CV solution at pH 6.5, where the microgels are negatively charged and the CV is positively charged. The electrostatic attraction holds the CV inside of the microgels, while a decrease of the solution pH can neutralize the microgels and allow for CV release. In this investigation, we show that when CV-loaded microgels are deposited on the anode in an electrochemical cell and an appropriate voltage applied, there is a decrease in the solution pH near the anode surface that allows for CV release. We also show that removing the applied potential allows the solution pH near the anode to return to pH 6.5, which halts the release. We show that the release rate from the microgel-modified anodes could be controlled by the magnitude of the applied voltage and by pulsing the applied voltage or applying a continuous voltage. Furthermore, we showed that the microgel-modified anodes can be reloaded with CV and used to release CV to a system many times. Such devices could be used as implantable drug delivery devices, as well as for industrial applications, where small molecules need to be released to systems in response to their chemical status.
一层聚（N-异丙基丙烯酰胺-共-丙烯酸）微凝胶被沉积在 Au 电极上，并用于电触发小分子结晶紫（CV）的释放，CV 被用作模型药物。通过将微凝胶暴露于 pH 6.5 的 CV 溶液中，可以将 CV 加载到表面结合的微凝胶中，在该 pH 值下，微凝胶带负电荷，而 CV 带正电荷。静电吸引将 CV 保持在微凝胶内，而溶液 pH 值的降低可以中和微凝胶并允许 CV 释放。在这项研究中，我们表明，当 CV 负载的微凝胶沉积在电化学电池的阳极上并施加适当的电压时，阳极表面附近的溶液 pH 值会降低，从而允许 CV 释放。我们还表明，去除施加的电势会使阳极附近的溶液 pH 值恢复到 pH 6.5，从而停止释放。我们表明，通过施加的电压的大小以及通过脉冲施加电压或施加连续电压，可以控制从微凝胶修饰的阳极的释放速率。此外，我们表明，微凝胶修饰的阳极可以重新加载 CV 并用于多次向系统释放 CV。这种装置可用作植入式药物输送装置，以及用于工业应用，其中需要根据化学状态将小分子释放到系统中。
