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Errors in energy landscapes measured with particle tracking

Accepted version
Peer-reviewed

Type

Article

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Authors

Savin, TH 
Bogdan, Michał 

Abstract

Tracking Brownian particles is often employed to map the energy landscape they explore. Such measurements have been exploited to study many biological processes and interactions in soft materials. Yet, video tracking is irremediably contaminated by localization errors originating from two imaging artifacts: the static'' errors come from signal noise, and the dynamic'' errors arise from the motion blur due to finite frame acquisition time. We show that these errors result in systematic and non-trivial biases in the measured energy landscapes. We derive a relationship between the true and the measured potential that elucidates, among other aberrations, the presence of false double-well minima in the apparent potentials reported in recent studies. We further assess several canonical trapping and pair-interaction potentials, by using our analytically derived results and Brownian dynamics simulations. In particular, we show that the apparent spring stiffness of harmonic potentials (such as optical traps) is increased by dynamic errors, but decreased by static errors. Our formula allows for the development of efficient corrections schemes, and we also present in this paper a provisional method for reconstructing true potentials from the measured ones.

Description

Keywords

Optical Tweezers, Thermodynamics, Time Factors

Journal Title

Biophysical Journal

Conference Name

Journal ISSN

1542-0086
1542-0086

Volume Title

115

Publisher

Elsevier