Active Gels Driven by the Belousov–Zhabotinsky Reaction

We explore research on autonomous gel actuators and gel machines driven by chemical reaction networks. We focused on the BZ reaction. The BZ reaction consists of a typical chemical reaction network. The Belousov–Zhabotinsky (BZ) reaction, known as a chemical oscillation, is a chemical reaction that induces self-oscillation in concentration. The catalyst of the BZ reaction is covalently bonded to the polymer chain so that the BZ reaction occurs only inside the gel, and the change of the osmotic pressure associated with the oscillation of concentration causes periodic swelling and shrinkage of the gel. The essence of the coupling between the BZ reaction and the gel is that the swelling and contraction motion of the gel can sufficiently follow the chemical reaction, and we have designed peristaltic motion of polymer gels and self-walking gels.<br/>Recently, we have proposed a new hypothesis regarding the temperature–compensated biological clock using temperature–responsive BZ gels. The temperature compensation of the biological clock is the property of maintaining a constant cycle regardless of changes in temperature, and the mechanism of the temperature compensation is not clearly understood. By constructing a mathematical model of the temperature–responsive BZ gel and analyzing it theoretically, we found that the temperature compensation can be realized by offsetting the effect of temperature change by volume change of the BZ gel. Our experiments also showed that the temperature–responsive BZ gel exhibits temperature compensation, and we succeeded in designing an artificial biological clock.