Islam Molla R, Irvine Jessica, Serpe Michael J
Department of Chemistry, University of Alberta , Edmonton, AB T6G 2G2, Canada.
ACS Appl Mater Interfaces. 2015 Nov 4;7(43):24370-6. doi: 10.1021/acsami.5b08532. Epub 2015 Oct 26.
Poly(N-isopropylacrylamide) microgel-based optical devices were designed such that they can be stimulated to change their optical properties in response to light produced by a light-emitting diode (LED). The devices were fabricated by sandwiching the synthesized microgels between two Cr/Au layers all supported on a glass coverslip with gold nanoparticles (AuNPs) deposited. Here, we found that these devices can be stimulated to change their optical properties when exposed to green LED light, which excites the AuNPs and increases the local temperature, causing the thermoresponsive microgels to decrease in diameter, resulting in a change in the devices' optical properties. We also found that the sensitivity of the devices to light was more pronounced as the environmental temperature approached the lower critical solution temperature (LCST) for the microgels, although the sensitivity of the devices to light exposure dropped off dramatically as the environmental temperature was increased above the LCST. This was a direct result of the microgels already being in their collapsed state and therefore unable to decrease in diameter any further due to light exposure. Finally, we found that the sensitivity of the devices to light exposure increased with increasing number of AuNP layers in the devices. We anticipate that these devices could be used for drug delivery applications; by using light to stimulate microgel collapse, the microgel-based devices can be stimulated to release small molecules on demand.
基于聚（N-异丙基丙烯酰胺）微凝胶的光学器件被设计成能够响应发光二极管（LED）产生的光而被刺激改变其光学性质。这些器件是通过将合成的微凝胶夹在两个Cr/Au层之间制造而成的，所有这些都支撑在一个沉积了金纳米颗粒（AuNPs）的玻璃盖玻片上。在这里，我们发现当这些器件暴露于绿色LED光时，它们能够被刺激改变其光学性质，绿色LED光会激发AuNPs并升高局部温度，导致热响应性微凝胶直径减小，从而导致器件光学性质发生变化。我们还发现，当环境温度接近微凝胶的低临界溶液温度（LCST）时，器件对光的敏感度更加明显，尽管当环境温度升高到高于LCST时，器件对光照射的敏感度会急剧下降。这是微凝胶已经处于其塌陷状态的直接结果，因此由于光照射而无法进一步减小直径。最后，我们发现器件对光照射的敏感度随着器件中AuNP层数的增加而增加。我们预计这些器件可用于药物递送应用；通过使用光刺激微凝胶塌陷，可以刺激基于微凝胶的器件按需释放小分子。
