Nanoprobes for Nonequilibrium Driven Systems

Introduction

At the core of far-from-equilibrium biological activity lies an orchestra of molecular motors, constantly dissipating energy while converting chemical fuel into mechanical work. Estimating the amount of the free energy budget lost to dissipation is crucial for a deeper understanding of the underlying nonequilibrium dynamics and for unraveling the thermodynamic constraints on the possible biological processes.

Theoretical Background

Although there are theoretical tools for quantifying nonequilibrium activity and dissipation in the framework of stochastic thermodynamics, there is a gap between these analytical calculations and their experimental applicability. The difficulty stems from the limited accessibility to the myriad degrees of freedom of complex systems and the finite measurement resolution, which can mask the footprints of nonequilibrium dynamics, such that they may appear as passive thermal fluctuations.

Proposed Approach

I will address this challenge both experimentally and theoretically. In my lab, I will develop fluorescent nanosensors for unveiling microscopic activity otherwise inaccessible in complex biological systems.

Sensor Development

• Fluorescent single-walled carbon nanotubes with tailored functionalization will transduce molecular-motor activity to a modulation of the emitted fluorescence.
• This will provide a novel degree of freedom never before exploited as a phase-space coordinate for inferring dissipation in nonequilibrium systems.

Experimental Implementation

I will incorporate the nanotube sensors in minimal biomimetic models of active systems, including:

1. DNA-gel
2. Reconstituted cytoskeleton driven by molecular motors

This will demonstrate my approach in a highly controlled environment.

Live Cell Applications

Further, I will internalize the nanotubes within live cells and utilize the fluorescence signal to estimate the dissipation in nonequilibrium intracellular organization.

Theoretical Advancements

In parallel, I will advance theoretical tools for estimating the dissipation from experimental data, based on an approach I have pioneered for detecting time-irreversibility.