Measuring Nanoscale Torques with Cylindrical-Polarization-based Interferometric Scattering Microscopy

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Main Authors: Vala, Milan, Kopal, Ivan, Takiguchi, Lauren, Shaidiuk, Yevhenii, Lužný, Vítězslav, Bujak, Łukasz, Kosuri, Pallav, Piliarik, Marek
Format: Preprint
Published: 2026
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author Vala, Milan
Kopal, Ivan
Takiguchi, Lauren
Shaidiuk, Yevhenii
Lužný, Vítězslav
Bujak, Łukasz
Kosuri, Pallav
Piliarik, Marek
author_facet Vala, Milan
Kopal, Ivan
Takiguchi, Lauren
Shaidiuk, Yevhenii
Lužný, Vítězslav
Bujak, Łukasz
Kosuri, Pallav
Piliarik, Marek
contents The ability to observe rotational dynamics and measure underlying torques is a crucial component in understanding the function and mechanics of nanoscale systems. Yet, direct observation of rotational dynamics at the single-molecule level in liquids remains challenging due to the trade-off between optical detectability and hydrodynamic responsiveness. Labels that are bright enough for rapid readout typically introduce excessive drag, while minimally perturbing probes are difficult to detect at high speed. This limits access to fast rotational dynamics required for direct torque measurements. Here, we introduce cylindrical-polarization-based interferometric scattering microscopy (cypiSCAT), a method encoding the orientation of anisotropic scatterers directly into a single interferometric point spread function, while intrinsically suppressing the isotropic background. We achieve rotational tracking of low-drag orientation labels based on DNA origami-attached gold nanorods with sub-degree angular precision and microsecond temporal resolution, allowing quantitative characterization of nanoscale rotational dynamics. This capability provides direct access to torque metrology at the single-molecule level, here demonstrated through the extraction of optically induced torques as small as ~1 pN nm. Relying on elastic scattering, cypiSCAT combines ultrafast temporal resolution with long observation times, making it well-suited for capturing rapid and rare rotational events and reaction steps in nanoscale biomolecular systems.
format Preprint
id arxiv_https___arxiv_org_abs_2601_08373
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Measuring Nanoscale Torques with Cylindrical-Polarization-based Interferometric Scattering Microscopy
Vala, Milan
Kopal, Ivan
Takiguchi, Lauren
Shaidiuk, Yevhenii
Lužný, Vítězslav
Bujak, Łukasz
Kosuri, Pallav
Piliarik, Marek
Optics
The ability to observe rotational dynamics and measure underlying torques is a crucial component in understanding the function and mechanics of nanoscale systems. Yet, direct observation of rotational dynamics at the single-molecule level in liquids remains challenging due to the trade-off between optical detectability and hydrodynamic responsiveness. Labels that are bright enough for rapid readout typically introduce excessive drag, while minimally perturbing probes are difficult to detect at high speed. This limits access to fast rotational dynamics required for direct torque measurements. Here, we introduce cylindrical-polarization-based interferometric scattering microscopy (cypiSCAT), a method encoding the orientation of anisotropic scatterers directly into a single interferometric point spread function, while intrinsically suppressing the isotropic background. We achieve rotational tracking of low-drag orientation labels based on DNA origami-attached gold nanorods with sub-degree angular precision and microsecond temporal resolution, allowing quantitative characterization of nanoscale rotational dynamics. This capability provides direct access to torque metrology at the single-molecule level, here demonstrated through the extraction of optically induced torques as small as ~1 pN nm. Relying on elastic scattering, cypiSCAT combines ultrafast temporal resolution with long observation times, making it well-suited for capturing rapid and rare rotational events and reaction steps in nanoscale biomolecular systems.
title Measuring Nanoscale Torques with Cylindrical-Polarization-based Interferometric Scattering Microscopy
topic Optics
url https://arxiv.org/abs/2601.08373