Ma Chao, Peng Shuyi, Chen Lian, Cao Xingyu, Sun Ye, Chen Lin, Yang Lang, Ma Chunming, Liu Qijie, Liu Zhenzhong, Jiang Shaohua
State Key Laboratory of Marine Resource Utilization in South China Sea, Hainan University, Haikou 570228, China.
Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, International Innovation Center for Forest Chemicals and Materials, College of Materials Science and Engineering, Nanjing Forestry University, Nanjing 210037, China.
Gels. 2023 May 25;9(6):438. doi: 10.3390/gels9060438.
Stimuli-responsive color-changing and shape-changing hydrogels are promising intelligent materials for visual detections and bio-inspired actuations, respectively. However, it is still an early stage to integrate the color-changing performance and shape-changing performance together to provide bi-functional synergistic biomimetic devices, which are difficult to design but will greatly expand further applications of intelligent hydrogels. Herein, we present an anisotropic bi-layer hydrogel by combining a pH-responsive rhodamine-B (RhB)-functionalized fluorescent hydrogel layer and a photothermal-responsive shape-changing melanin-added poly (N-isopropylacrylamide) (PNIPAM) hydrogel layer with fluorescent color-changing and shape-changing bi-functional synergy. This bi-layer hydrogel can obtain fast and complex actuations under irradiation with 808 nm near-infrared (NIR) light due to both the melanin-composited PNIPAM hydrogel with high efficiency of photothermal conversion and the anisotropic structure of this bi-hydrogel. Furthermore, the RhB-functionalized fluorescent hydrogel layer can provide rapid pH-responsive fluorescent color change, which can be integrated with NIR-responsive shape change to achieve bi-functional synergy. As a result, this bi-layer hydrogel can be designed using various biomimetic devices, which can show the actuating process in the dark for real-time tracking and even mimetic starfish to synchronously change both the color and shape. This work provides a new bi-layer hydrogel biomimetic actuator with color-changing and shape-changing bi-functional synergy, which will inspire new strategies for other intelligent composite materials and high-level biomimetic devices.
刺激响应型变色和变形水凝胶分别是用于视觉检测和生物启发驱动的很有前景的智能材料。然而，将变色性能和变形性能整合在一起以提供双功能协同仿生装置仍处于早期阶段，这种装置难以设计，但将极大地扩展智能水凝胶的进一步应用。在此，我们通过将pH响应型罗丹明B（RhB）功能化荧光水凝胶层与添加了光热响应型变形黑色素的聚（N-异丙基丙烯酰胺）（PNIPAM）水凝胶层相结合，呈现出一种具有荧光变色和变形双功能协同作用的各向异性双层水凝胶。由于黑色素复合的PNIPAM水凝胶具有高效的光热转换效率以及这种双水凝胶的各向异性结构，这种双层水凝胶在808 nm近红外（NIR）光照射下可实现快速且复杂的驱动。此外，RhB功能化荧光水凝胶层可提供快速的pH响应荧光颜色变化，其可与近红外响应形状变化相结合以实现双功能协同。因此，这种双层水凝胶可用于设计各种仿生装置，这些装置能在黑暗中展示驱动过程以进行实时跟踪，甚至可模仿海星同步改变颜色和形状。这项工作提供了一种具有变色和变形双功能协同作用的新型双层水凝胶仿生致动器，这将为其他智能复合材料和高级仿生装置激发新的策略。
