Confining Brownian motion of single nanoparticles in an ABELtrap

TL;DR

This paper demonstrates a method to confine and observe the dynamic behavior of single nanoparticles and proteins in solution using an active feedback electrokinetic trap, enabling extended observation of their conformational changes.

Contribution

The study introduces an improved ABELtrap system that effectively confines sub-100nm nanoparticles and proteins, facilitating detailed single-molecule analysis in solution.

Findings

Successfully trapped and observed nanoparticles and proteins in solution.

Demonstrated confinement of particles using electrokinetic feedback.

Enabled extended observation of conformational dynamics.

Abstract

Trapping nanoscopic objects to observe their dynamic behaviour for extended periods of time is an ongoing quest. Particularly, sub-100nm transparent objects are hard to catch and most techniques rely on immobilisation or transient diffusion through a confocal laser focus. We present an Anti-Brownian ELectrokinetic trap (pioneered by A. E. Cohen and W. E. Moerner) to hold nanoparticles and individual FoF1-ATP synthase proteins in solution. We are interested in the conformational dynamics of this membrane-bound rotary motor protein that we monitor using single-molecule FRET. The ABELtrap is an active feedback system cancelling the nano-object's Brownian motion by applying an electric field. We show how the induced electrokinetic forces confine the motion of nanoparticles and proteoliposomes to the centre of the trap.