利用纳米等离激元开关实现酶催化反应的光逻辑控制

Different reactions catalyzed by enzymes within cells, which contain reaction cascades or circuits, often occur in parallel and proceed with the necessary spatial and temporal control without unwanted interference from other reaction pathways, because enzyme activity is often modulated through feedback loops and a variety of trigger-induced effects. Inspired by this, implementation of ‘bio-like’ level of control over chemical transformations in artificial catalysis system is of great value for engineering the application of enzyme in vitro and improvement of catalytic efficiency in multiple enzyme systems that are performed in one-pot reactors. This project aims to construct catalytic structures that have logic control switches allowing catalytic functionalities in a single pot reactor that can be independently activated and deactivated. The logic control switch will be activated through the plasmon-mediated transfer of resonant photon energy, in forms of electrons and holes. Plasmon-mediated photon absorption is activated by small bands of photon wavelengths while being passive for non-resonant wavelengths, which enables a digital switch for activating redox reactions. Plasmonic@semicondutor core-shell structures involving different semiconducting types can exclusively transfer plasmon excited hot electrons or holes to coenzymes coupled to them and consequentially change the redox states of coenzymes. By designing kinds of plasmonic nanostructures without resonance wavelength overlapping, photoactivated logic control switches that dependently trigger targeted catalytic reactions can be achieved by shining color lights uniquely matching the plasmon resonances. The concept of logic control in this proposal would be able to conquer the obstacles for achieving controllability and efficiency of catalytic processes in one-pot systems.

细胞内平行发生着许多不同的酶催化反应，存在一系列级联反应与循环回路，它们在特定的时间、空间进行而且反应路径互不干涉。如果能在人造催化系统中实现类似效果，对于开发酶催化活性的体外应用、提高多酶偶联催化效率等将具有深刻意义。本项目拟构建一种光激活的开关，在包含多种酶的体系中逻辑控制每个催化过程独立地激活和关闭。这种逻辑控制开关充分利用了等离激元共振及能量转移的过程只能被特定波长的光所激发的特性。具有不同半导体类型的等离激元金属@半导体核壳结构选择性地将激发出的热电子或热空穴转移至与之耦合的辅酶因子上，从而改变辅酶因子的氧化还原状态，建立多次循环的氧化还原回路。通过设计几个响应波长没有重合的光激活开关，单独地触发某个酶催化反应，实现多酶偶联体系中独立地对所需反应进行光响应逻辑控制，达到在“一锅式”反应系统内可控合成、优化效率的目的。

本项目将纳米等离激元材料的光学特性与酶的催化活性结合，设计了一种无机/生物复合体系。根据等离激元纳米材料（包括Ag、Au）光学性质的特征波长的不同，以及半导体纳米材料的类型的不同，构建了一系列波长响应的“核-壳”型复合结构，可以作为激活化学反应的纳米等离激元光开关。在贵金属纳米结构作为“核”的材料制备中，通过形成合金的方式，对贵金属纳米材料的光学性质和电子结构进行调控，发展了等离激元耦合价带杂化策略调控化学反应选择性的方法。在原位制备Ag@TiO2的核壳结构及负载结构的探索中，发展了一种富集并原位还原Ag+离子成为Ag纳米颗粒的方法，并设计了无标记、可视化检测Ag+离子的纳米等离激元传感策略。最后，研究了上述几种等离激元金属@半导体材料的核壳结构在辅酶因子NAD+/NADH氧化还原反应循环中的催化效果，在等离激元响应波长的单色光的激发下，完成NADH的高效重生，并建立了纳米等离激元控制光-酶偶联体系中的级联反应的方法。实现了等离激元热载流子的可调控传递，开拓了纳米等离激元材料在酶催化中的应用，阐明了光生物催化中热载流子的作用机制。