{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"institution":[{"name":"bioRxiv"}],"indexed":{"date-parts":[[2026,9,16]],"date-time":"2026-09-16T14:07:36Z","timestamp":1789567656748,"version":"build-2803163510"},"posted":{"date-parts":[[2026,9,10]]},"group-title":"Biophysics","reference-count":67,"publisher":"openRxiv","license":[{"start":{"date-parts":[[2026,9,10]],"date-time":"2026-09-10T00:00:00Z","timestamp":1788998400000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc-nd\/4.0\/"}],"funder":[{"award":["RF1AG079294"],"award-info":[{"award-number":["RF1AG079294"]}],"id":[{"id":"https:\/\/ror.org\/01cwqze88","id-type":"ROR","asserted-by":"publisher"}]},{"award":["R01AG087295"],"award-info":[{"award-number":["R01AG087295"]}],"id":[{"id":"https:\/\/ror.org\/01cwqze88","id-type":"ROR","asserted-by":"publisher"}]},{"award":["GM145437"],"award-info":[{"award-number":["GM145437"]}],"id":[{"id":"https:\/\/ror.org\/01cwqze88","id-type":"ROR","asserted-by":"publisher"}]},{"award":["S10OD025072"],"award-info":[{"award-number":["S10OD025072"]}],"id":[{"id":"https:\/\/ror.org\/01cwqze88","id-type":"ROR","asserted-by":"publisher"}]},{"award":["S10RR026680"],"award-info":[{"award-number":["S10RR026680"]}],"id":[{"id":"https:\/\/ror.org\/01cwqze88","id-type":"ROR","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"accepted":{"date-parts":[[2026,9,10]]},"abstract":"<jats:title>ABSTRACT<\/jats:title>\n                <jats:p>\n                  Heavy water (D\n                  <jats:sub>2<\/jats:sub>\n                  O) is widely used in biomolecular spectroscopy and imaging, often under the assumption that it is an inert replacement for H\n                  <jats:sub>2<\/jats:sub>\n                  O. However, D\n                  <jats:sub>2<\/jats:sub>\n                  O differs subtly in hydrogen-bonding, viscosity, and dielectric properties, which can alter biomolecular interactions and self-assembly. Here, we test how solvent isotope substitution modulates protein\/peptide phase separation and amyloid formation in multiple intrinsically disordered systems. Using turbidity-based phase diagrams and microscopy, we quantify how D\n                  <jats:sub>2<\/jats:sub>\n                  O shifts protein-RNA complex coacervation boundaries and alters condensate morphology. Droplet recovery measurements indicate significant solvent-dependent changes in condensate material properties. We further evaluate amyloid formation kinetics, in the presence or absence of a cofactor, supported by orthogonal structural characterization, and assess the functional consequences of tau fibrils using a tau biosensor seeding assay with explicitly defined seed delivery conditions. Together, these results show that D\n                  <jats:sub>2<\/jats:sub>\n                  O can systematically bias liquid-liquid phase separation and aggregation readouts and should be treated as an active experimental variable rather than a neutral solvent substitute.\n                <\/jats:p>","DOI":"10.64898\/2026.09.08.748679","type":"posted-content","created":{"date-parts":[[2026,9,11]],"date-time":"2026-09-11T14:25:44Z","timestamp":1789136744000},"source":"Crossref","is-referenced-by-count":0,"title":["Solvent-Isotope Effects in Biomolecular Phase Separation and Fibrillation of Disordered Proteins and Peptides"],"prefix":"10.64898","author":[{"given":"Hanuman","family":"Singh","sequence":"first","affiliation":[{"name":"Department of Chemistry, University of Colorado, Boulder, CO 80309, United States"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Zayne","family":"Yeager","sequence":"additional","affiliation":[{"name":"Department of Chemistry, University of Colorado, Boulder, CO 80309, United States"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Morgane","family":"Herlory","sequence":"additional","affiliation":[{"name":"Department of Chemistry, University of Colorado, Boulder, CO 80309, United States"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sayanta","family":"Mahapatra","sequence":"additional","affiliation":[{"name":"Department of Chemistry, University of Colorado, Boulder, CO 80309, United States"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8049-0817","authenticated-orcid":false,"given":"Maciej A.","family":"Walczak","sequence":"additional","affiliation":[{"name":"Department of Chemistry, University of Colorado, Boulder, CO 80309, United States"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"54368","reference":[{"key":"2026091606301496000_2026.09.08.748679v1.1","doi-asserted-by":"publisher","DOI":"10.1126\/science.aaf4382"},{"key":"2026091606301496000_2026.09.08.748679v1.2","doi-asserted-by":"publisher","DOI":"10.1146\/annurev-cellbio-100913-013325"},{"key":"2026091606301496000_2026.09.08.748679v1.3","doi-asserted-by":"publisher","DOI":"10.1038\/nrm.2017.7"},{"key":"2026091606301496000_2026.09.08.748679v1.4","doi-asserted-by":"publisher","DOI":"10.1016\/j.cell.2015.09.015"},{"key":"2026091606301496000_2026.09.08.748679v1.5","doi-asserted-by":"crossref","unstructured":"Pei, G. ; Wang, X. ; Quan, X. ; Geng, D. ; Chen, Z. ; Xu, W. ; Huang, K. ; Li, T. ; Li, P. , Opposing roles of serine and charge in IDR condensate miscibility. 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