A hydrogel with dual thermo and photoresponsive characteristics was developed. Using poly(N-isopropylacrylamide) (PNIPAM) as the thermosensitive unit, the hydrogel network can undergo reversible swelling/shrinking behavior under different temperatures (20 °C and 37 °C) stimulation. A supramolecular host–guest complex composed of azobenzene (Azo) and α-cyclodextrin (α-CD) was used as the photosensitive unit. Azo and α-CD can undergo reversible recombination/dissociation behavior under the stimulation of different wavelengths of light (365 nm and 430 nm). Methylene blue (MB) was selected as the model drug to measure the controlled release behavior of the hydrogel under different temperatures and photoirradiations. The experimental results showed that the hydrogel containing the thermosensitive component (PNIPAM) and the photosensitive component (α-CD/Azo) released 69.3% and 47.2% of MB at 20 °C and 37 °C, respectively. Under the condition of light wavelengths at 430 nm and 365 nm, 73.2% and 65.6% of MB were released, respectively. The results showed that α-CD and Azo formed a supramolecular host–guest complex, which could undergo reversible binding/dissociation under the action of light stimulation, thereby controlling MB to enter and exit CD cavity. In addition, when the ambient temperature was lower or higher than the lower critical solution temperature of PNIPAM (LCST, 32 °C), the hydrogel underwent a responsive volume change to control the loading and release of MB molecules. So, combining the dual thermo and photoresponsibility, this smart hydrogel could be applied for multiple controlled release mechanisms.

中文翻译：

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具有多种控制释放机制的热响应和光响应双重性能水凝胶

开发了具有热和光响应双重特性的水凝胶。使用聚（N-异丙基丙烯酰胺）（PNIPAM）作为热敏单元，水凝胶网络在不同温度（20°C和37°C）刺激下会经历可逆的溶胀/收缩行为。由偶氮苯（Azo）和α-环糊精（α -CD）组成的超分子主客体复合物被用作光敏单元。偶氮和α-CD在不同波长的光（365nm和430nm）的刺激下可以经历可逆的重组/解离行为。选择亚甲基蓝（MB）作为模型药物，以测量水凝胶在不同温度和光辐照下的控释行为。实验结果表明，含有热敏组分（PNIPAM）和光敏组分（α -CD / Azo）的水凝胶在20°C和37°C时分别释放69.3％和47.2％的MB。在430 nm和365 nm的光波长条件下，分别释放了73.2％和65.6％的MB。结果表明，α-CD和Azo形成了超分子宿主-客体复合物，在光刺激的作用下可发生可逆的结合/解离，从而控制MB进入和退出CD腔。此外，当环境温度低于或高于PNIPAM的较低临界溶液温度（LCST，32°C）时，水凝胶会发生响应的体积变化，以控制MB分子的负载和释放。因此，结合了热和光的双重责任，这种智能水凝胶可用于多种控释机制。