Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada.
ACS Appl Mater Interfaces. 2020 Apr 22;12(16):19062-19068. doi: 10.1021/acsami.0c03928. Epub 2020 Apr 7.
Stretchable poly(-isopropylacrylamide)--acrylic acid (pNIPAm--10% AAc) microgel-based reservoir devices were fabricated and used to control the release rate of the small molecule model drug tris(4-(dimethylamino)phenyl)methylium chloride (crystal violet, CV) to solution by varying the Au layer thickness coating the microgels and device elongation. Specifically, we showed that CV could be loaded into the microgel layer of the devices via electrostatic interactions at pH 6.5, and the release could be triggered upon exposure to a pH 3.0 solution, which breaks the microgel-CV electrostatic interactions. We demonstrated that the rate of release could be increased by decreasing the Au layer thickness coating microgels and by stretching, that is, thin Au and high elongation promoted the relatively fast release of CV from the device. We found that the Au overlayer thickness (and porosity) dominated the observed release rate profiles when the device was not stretched (or at low elongation), while elongation-induced cracks dominated the release rate at high elongation. We also showed that the CV release kinetics could transition from low ("off") to high ("on"), which enhanced when the devices are stretched. This behavior could be exploited in the future for autonomous release systems that release small molecules when stretched by natural processes, for example, movement of joints and muscles.
可拉伸的聚（异丙基丙烯酰胺）-丙烯酸（pNIPAm-10%AAc）微凝胶基储库器件被制备并用于通过改变涂覆微凝胶和器件伸长的 Au 层厚度来控制小分子模型药物三（4-（二甲氨基）苯基）甲基氯化铵（结晶紫，CV）向溶液中的释放速率。具体而言，我们表明 CV 可以通过在 pH 6.5 下通过静电相互作用加载到器件的微凝胶层中，并且可以在暴露于 pH 3.0 溶液时触发释放，这破坏了微凝胶-CV 静电相互作用。我们证明，通过减小涂覆微凝胶的 Au 层厚度和拉伸，可以增加释放速率，即薄的 Au 和高的伸长率促进了 CV 从器件中的相对快速释放。我们发现，当器件未拉伸（或伸长率较低）时，Au 覆盖层厚度（和孔隙率）主导观察到的释放速率曲线，而伸长诱导的裂缝在高伸长率下主导释放速率。我们还表明，CV 的释放动力学可以从低（“关闭”）转变为高（“打开”），当器件拉伸时会增强。这种行为可用于未来的自主释放系统，例如通过自然过程（例如关节和肌肉的运动）拉伸时释放小分子。
