@misc{balk_enzymatically_triggered_2021, 
author={Balk, M., Behl, M., Nöchel, U., Lendlein, A.},
title={Enzymatically Triggered Jack-in-the-Box-like Hydrogels},
year={2021},
howpublished = {journal article},
doi = {https://doi.org/10.1021/acsami.1c00466},
abstract = {Enzymes can support the synthesis or degradation of biomacromolecules in natural processes. Here, we demonstrate that enzymes can induce a macroscopic-directed movement of microstructured hydrogels following a mechanism that we call a “Jack-in-the-box” effect. The material’s design is based on the formation of internal stresses induced by a deformation load on an architectured microscale, which are kinetically frozen by the generation of polyester locking domains, similar to a Jack-in-the-box toy (i.e., a compressed spring stabilized by a closed box lid). To induce the controlled macroscopic movement, the locking domains are equipped with enzyme-specific cleavable bonds (i.e., a box with a lock and key system). As a result of enzymatic reaction, a transformed shape is achieved by the release of internal stresses. There is an increase in entropy in combination with a swelling-supported stretching of polymer chains within the microarchitectured hydrogel (i.e., the encased clown pops-up with a pre-stressed movement when the box is unlocked). This utilization of an enzyme as a physiological stimulus may offer new approaches to create interactive and enzyme-specific materials for different applications such as an optical indicator of the enzyme’s presence or actuators and sensors in biotechnology and in fermentation processes.},
note = {Online available at: \url{https://doi.org/10.1021/acsami.1c00466} (DOI). Balk, M.; Behl, M.; Nöchel, U.; Lendlein, A.: Enzymatically Triggered Jack-in-the-Box-like Hydrogels. ACS Applied Materials and Interfaces. 2021. vol. 13, no. 7, 8095-8101. DOI: 10.1021/acsami.1c00466}}