Quantum tunnelling-integrated optoplasmonic nanotrap enables conductance visualisation of individual proteins

TL;DR

The paper introduces a novel optoplasmonic nanotrap platform that enables real-time, single-molecule conductance measurements of proteins, revealing their structural dynamics and electron transfer mechanisms with high spatial and temporal resolution.

Contribution

It presents the QTOP-trap, a new label-free method combining plasmonic trapping and quantum tunnelling to study protein conductance in physiological conditions.

Findings

Achieves sub-3 nm spatial precision.

Provides 10-μs temporal resolution.

Correlates protein structure dynamics with conductance.

Abstract

Biological electron transfer (ET) relies on quantum mechanical tunnelling through a dynamically folded protein. Yet, the spatiotemporal coupling between structural fluctuations and electron flux remains poorly understood, largely due to limitations in existing experimental techniques, such as ensemble averaging and non-physiological operating conditions. Here, we introduce a quantum tunnelling-integrated optoplasmonic nanotrap (QTOP-trap), an optoelectronic platform that combines plasmonic optical trapping with real-time quantum tunnelling measurements. This label-free approach enables single-molecule resolution of protein conductance in physiological electrolytes, achieving sub-3 nm spatial precision and 10-{\mu}s temporal resolution. By synchronising optoelectronic measurements, QTOP-trap resolves protein-specific conductance signatures and directly correlates tertiary structure dynamics with conductance using a "protein switch" strategy. This methodology establishes a universal framework for dissecting non-equilibrium ET mechanisms in individual conformational-active proteins, with broad implications for bioenergetics research and biomimetic quantum device design.