A Controllable Photoresponsive Potassium Transporter

Artificial photoresponsive transport systems are particularly intriguing because they offer the potential for precise spatio-temporal control, rapid response times and minimal toxicity associated with the light. We report here a controllable, photoresponsive, ion-transporting carrier, achieving controllability through a photoregulated β-cyclodextrin (β-CD)-azobenzene host-guest complex. In this complex, a lipid-anchored β-CD serves as the launch base, tightly immobilizing through host-guest interactions the otherwise freely moving trans-transporter derived from a crown ether-modified trans-azobenzene motif, but rapidly releasing most of it upon 365 nm UV irradiation that converts transporter to its cis-configuration. The launched cis-transporter functions well as a highly efficient potassium transporter, delivering a low EC50 value of 1.51 μM and a drastic transport activity enhancement by ~ 400% relative to the base-bound trans-transporter (EC50 = 7.46 μM), with on-off activities repeatedly regulated by light. In the absence of the base, the on-off activities between cis- and trans-transporters however differ by only 80% (1.35 μM vs 2.45 μM).

人工光响应传输系统格外引人关注，因其具备实现精确时空调控、快速响应以及伴随光照的极低毒性的潜力。本研究报道了一种可调控的光响应型离子传输载体，其可控性通过光调控的β-环糊精（β-cyclodextrin，β-CD）-偶氮苯（azobenzene）主客体复合物实现。在该复合物中，脂质锚定的β-环糊精充当锚定基底，通过主客体相互作用紧密固定原本可自由移动的、源自冠醚修饰反式偶氮苯基元的反式构型转运体；而当施加365 nm紫外辐照将转运体转化为顺式构型时，该基底会快速释放绝大多数转运体。被释放的顺式构型转运体可作为高效钾离子转运体发挥功能，其半最大效应浓度（EC50）低至1.51 μM，相较于锚定基底结合的反式构型转运体（EC50=7.46 μM），转运活性提升约400%，且其通断活性可通过光照反复调控。然而，当不存在锚定基底时，顺式与反式构型转运体之间的通断活性差异仅为80%（分别为1.35 μM与2.45 μM）。