In Situ Self‐Assembly of Quantum Dots at the Plasma Membrane Mediates Energy Transfer‐Based Activation of Channelrhodopsin

Abstract

The use of nanoparticle (NP) bioconjugates to control the activity of membrane ion channels has recently emerged as a new paradigm for the activation of electrically excitable cells. An NP‐based strategy is reported for the specific activation of channelrhodopsin C1V1 (ChR‐C1V1) expressed in the plasma membrane of HEK 293T/17 cells. Hydrophilic CdSe/ZnS core–shell semiconductor quantum dots (QDs) are self‐assembled to the exofacial face of recombinantly expressed ChR‐C1V1 by metal affinity‐driven interaction of the QD ZnS shell with an N‐terminal hexahistidine tag displayed on ChR‐C1V1. This configuration enables the Förster resonance energy transfer (FRET)‐based excitation and activation of the 11‐cis‐retinal moiety of ChR‐C1V1 using the QD as a light harvesting transducer/energy donor. It is shown that the specific laser‐induced opening of the ChR‐C1V1 channel wherein the photoexcited QD (405 nm excitation, 530 nm emission) iteratively activates ChR‐C1V1 channels as confirmed using the voltage‐sensitive dye (VSD) bis‐(1,3‐diethylthiobarbituric acid)trimethine oxonol (DiSBAC2(3)). In the absence of the QD transducer, excitation of ChR‐C1V1‐expressing cells at 405 nm results in no activation of ChR‐C1V1. The results demonstrate the ability to controllably interface QDs with living cells for the activation of ChR membrane proteins and detail a new NP‐bioconjugate hybrid system for the specific activation of ion channels.