Designing Dual-functionalized Gels for Self-reconfiguration and Autonomous Motion

Abstract

Human motion is enabled by the concerted expansion and contraction of interconnected muscles that are powered by inherent biochemical reactions. One of the challenges in the field of biomimicry is eliciting this form of motion from purely synthetic materials, which typically do not generate internalized reactions to drive mechanical action. Moreover, for practical applications, this bio-inspired motion must be readily controllable. Herein, we develop a computational model to design a new class of polymer gels where structural reconfigurations and internalized reactions are intimately linked to produce autonomous motion, which can be directed with light. These gels contain both spirobenzopyran (SP) chromophores and the ruthenium catalysts that drive the oscillatory Belousov-Zhabotinsky (BZ) reaction. Importantly, both the SP moieties and the BZ reaction are photosensitive. When these dual-functionalized gels are exposed to non-uniform illumination, the localized contraction of the gel (due to the SP moieties) in the presence of traveling chemical waves (due to the BZ reaction) leads to new forms of spontaneous, self-sustained movement, which cannot be achieved by either of the mono-functionalized networks.

Chemothermally Driven Out‐of‐Equilibrium Materials for Macroscopic Motion

“…While a few examples showed enzyme switches to achieve chemically driven out‐of‐equilibrium behavior on visible scale, these systems did not yield any macroscopic motion [36,37] . The only chemically driven out‐of‐equilibrium system that generated macroscopic motion relies on the Belousov‐Zhabotinsky (BZ) oscillating reaction, limiting the scope for general applications [38,39] . Notably, He et al .…”

“…[36,37] The only chemically driven out-of-equilibrium system that generated macroscopic motion relies on the Belousov-Zhabotinsky (BZ) oscillating reaction, limiting the scope for general applications. [38,39] Notably, He et al reported a self-regulating 2dimensional surface that elegantly combines a bi-phasic microfluidic device with an exothermic reaction; [30] nevertheless, 3dimensional macroscopic actuation was not possible for this system.…”

From isolated structures to continuous networks: A categorization of cytoskeleton‐based motile engineered biological microstructures

“…Methylcellulose (teal) is used as a crowding agent to promote crosslinking of neighboring microtubules (Sasaki et al, ). (j) Synthetic network: Polymer gels with spirobenzopyran chromophores and ruthenium catalysts (blue and green, inset) drive the Belousov‐Zhabotinsky reaction leading to oscillatory motility in the active material (Kuksenok & Balazs, ). (k) Synthetic cluster: Pluroinic F127‐DA micelles, which form in the presence of the activated photo‐initiator Irgacure 2,959 (purple), crosslink to form potentially functional clusters (X. Liu et al, ).…”

Photo‐Controlled Waves and Active Locomotion

“…The BZ reaction typically runs at a pH of 0–2! Nonetheless, the ability of these systems not only to move but also to change shape suggests that the effort is worthwhile. Light is a powerful, versatile, and relatively noninvasive tool, and we are just at the beginning of learning how to exploit it to control chemically driven locomotion.…”