van den Akker Wouter P, van Benthem Rolf A T M, Voets Ilja K, van Hest Jan C M
Department of Chemistry & Chemical Engineering, Institute for Complex Molecular Systems, Bio-Organic Chemistry, Eindhoven University of Technology, Helix, P.O. Box 513, 5600MB Eindhoven, The Netherlands.
Department of Chemistry & Chemical Engineering, Self-Organizing Soft Matter, Eindhoven University of Technology, P.O. Box 513, 5600MB Eindhoven, The Netherlands.
ACS Appl Mater Interfaces. 2024 Apr 17;16(15):19642-19650. doi: 10.1021/acsami.4c02643. Epub 2024 Apr 3.
The fabrication of a soft actuator with a dampened actuation response is presented. This was achieved via the incorporation into an actuating hydrogel of urease-loaded pH-responsive bicontinuous nanospheres (BCNs), whose membrane was able to regulate the permeability and thus conversion of fuel urea into ammonia. The dampened response of these nanoreactors to the enzymatically induced pH change was translated to a pH-responsive soft actuator. In hydrogels composed of a pH-responsive and nonresponsive layer, the transient pH gradient yielded an asymmetric swelling behavior, which induced a bending response. The transient actuation profile could be controlled by varying the external fuel concentrations. Furthermore, we showed that the spatial organization of the BCNs within the actuator had a great influence on the actuation response. Embedding the urease-loaded nanoreactors within the active, pH-responsive layer resulted in a reduced response due to local substrate conversion in comparison to embedding them within the passive layer of the bilayer hydrogel. Finally, we were able to induce transient actuation in a hydrogel comprising two identical active layers by the immobilization of the BCNs within one specific layer. Upon addition of urea, a local pH gradient was generated, which caused accelerated swelling in the BCN layer and transient bending of the device before the pH gradient was attenuated over time.
本文介绍了一种具有阻尼驱动响应的软驱动器的制备方法。这是通过将负载脲酶的pH响应性双连续纳米球（BCN）掺入驱动水凝胶中来实现的，其膜能够调节渗透率，从而将燃料尿素转化为氨。这些纳米反应器对酶促诱导的pH变化的阻尼响应转化为pH响应性软驱动器。在由pH响应层和非响应层组成的水凝胶中，瞬态pH梯度产生不对称溶胀行为，从而引起弯曲响应。瞬态驱动曲线可以通过改变外部燃料浓度来控制。此外，我们表明，驱动器内BCN的空间组织对驱动响应有很大影响。与将负载脲酶的纳米反应器嵌入双层水凝胶的被动层相比，将其嵌入活性pH响应层会因局部底物转化而导致响应降低。最后，通过将BCN固定在一个特定层中，我们能够在包含两个相同活性层的水凝胶中诱导瞬态驱动。加入尿素后，会产生局部pH梯度，这会导致BCN层加速溶胀，并在pH梯度随时间衰减之前使器件产生瞬态弯曲。
