Tamba Masaaki, Murayama Keiji, Asanuma Hiroyuki, Nakakuki Takashi
Department of Systems Design and Informatics, Kyushu Institute of Technology, Iizuka 8208502, Japan.
Department of Biomolecular Engineering, Graduate School of Engineering, Nagoya University, Nagoya 4648603, Japan.
Micromachines (Basel). 2022 Jan 26;13(2):193. doi: 10.3390/mi13020193.
A molecular robot is an intelligent molecular system. A typical control problem of molecular robots is to maintain the concentration of a specific DNA strand at the desired level, which is typically attained by a molecular feedback control mechanism. A molecular feedback system can be constructed in a bottom-up method by transforming a nonlinear chemical reaction system into a pseudo-linear system. This method enables the implementation of a molecular proportional-integral (PI) controller on a DNA reaction system. However, a DNA reaction system is driven by fuel DNA strand consumption, and without a sufficient amount of fuel strands, the molecular PI controller cannot perform normal operations as a concentration regulator. In this study, we developed a design method for a molecular PI control system to regenerate fuel strands by introducing photoresponsive reaction control. To this end, we employed a photoresponsive molecule, azobenzene, to guide the reaction direction forward or backward using light irradiation. We validated our renewable design of the PI controller by numerical simulations based on the reaction kinetics. We also confirmed the proof-of-principle of our renewable design by conducting experiments using a basic DNA circuit.
分子机器人是一种智能分子系统。分子机器人的一个典型控制问题是将特定DNA链的浓度维持在期望水平，这通常通过分子反馈控制机制来实现。分子反馈系统可以通过自下而上的方法构建，即将非线性化学反应系统转化为伪线性系统。这种方法能够在DNA反应系统上实现分子比例积分（PI）控制器。然而，DNA反应系统由燃料DNA链的消耗驱动，并且如果没有足够数量的燃料链，分子PI控制器就无法作为浓度调节器正常运行。在本研究中，我们开发了一种分子PI控制系统的设计方法，通过引入光响应反应控制来再生燃料链。为此，我们使用了一种光响应分子偶氮苯，利用光照射来引导反应向前或向后进行。我们通过基于反应动力学的数值模拟验证了PI控制器的可再生设计。我们还通过使用基本DNA电路进行实验，证实了我们可再生设计的原理验证。
