Effects of Rim Fluctuations in Classical Nucleation Theory of Virus Capsids

Fuente: arXiv
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Autori principali: Clark, Alexander Bryan, van der Schoot, Paul, Orland, Henri, Zandi, Roya
Natura: Preprint
Pubblicazione: 2026
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author Clark, Alexander Bryan
van der Schoot, Paul
Orland, Henri
Zandi, Roya
author_facet Clark, Alexander Bryan
van der Schoot, Paul
Orland, Henri
Zandi, Roya
contents Most spherical viruses exhibit icosahedral symmetry, yet the growth of viral shells remains poorly understood due to the short lifetimes and broad size distribution of assembly intermediates. Classical nucleation theory has been widely applied to describe this process, but it treats the boundary of a growing shell as rigid and structureless. Here, we extend classical nucleation theory by incorporating thermal fluctuations of the capsid rim using both discrete and continuum descriptions. Allowing the rim of a partially formed capsid to undergo small geometric undulations, we show that these fluctuations generate an entropic contribution that renormalizes the effective line tension. As a result, rim fluctuations can either promote or hinder capsid closure, depending on the subunit-subunit binding free energy, temperature, and fluctuation amplitude. We find that fluctuations generally lower the nucleation barrier when the binding free energy is below a threshold value, while for sufficiently strong binding, they can instead raise the barrier by stabilizing incomplete capsids through a finite-size entropy penalty associated with rim closure. By moving beyond the idealized capillarity approximation, our results provide a controlled extension of classical nucleation theory that clarifies how boundary fluctuations influence capsid nucleation and growth.
format Preprint
id arxiv_https___arxiv_org_abs_2603_07549
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Effects of Rim Fluctuations in Classical Nucleation Theory of Virus Capsids
Clark, Alexander Bryan
van der Schoot, Paul
Orland, Henri
Zandi, Roya
Soft Condensed Matter
Biological Physics
Most spherical viruses exhibit icosahedral symmetry, yet the growth of viral shells remains poorly understood due to the short lifetimes and broad size distribution of assembly intermediates. Classical nucleation theory has been widely applied to describe this process, but it treats the boundary of a growing shell as rigid and structureless. Here, we extend classical nucleation theory by incorporating thermal fluctuations of the capsid rim using both discrete and continuum descriptions. Allowing the rim of a partially formed capsid to undergo small geometric undulations, we show that these fluctuations generate an entropic contribution that renormalizes the effective line tension. As a result, rim fluctuations can either promote or hinder capsid closure, depending on the subunit-subunit binding free energy, temperature, and fluctuation amplitude. We find that fluctuations generally lower the nucleation barrier when the binding free energy is below a threshold value, while for sufficiently strong binding, they can instead raise the barrier by stabilizing incomplete capsids through a finite-size entropy penalty associated with rim closure. By moving beyond the idealized capillarity approximation, our results provide a controlled extension of classical nucleation theory that clarifies how boundary fluctuations influence capsid nucleation and growth.
title Effects of Rim Fluctuations in Classical Nucleation Theory of Virus Capsids
topic Soft Condensed Matter
Biological Physics
url https://arxiv.org/abs/2603.07549