{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,31]],"date-time":"2026-08-31T04:13:41Z","timestamp":1788149621194,"version":"build-2803163510"},"reference-count":51,"publisher":"American Chemical Society (ACS)","issue":"8","license":[{"start":{"date-parts":[[2026,7,17]],"date-time":"2026-07-17T00:00:00Z","timestamp":1784246400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100014013","name":"UK Research and Innovation","doi-asserted-by":"publisher","award":["EP\/Z000459\/1"],"award-info":[{"award-number":["EP\/Z000459\/1"]}],"id":[{"id":"10.13039\/100014013","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/na","name":"WolkswagenStiftung Lower Saxony ? i Israel Research Cooperation","doi-asserted-by":"publisher","award":["ZN5614"],"award-info":[{"award-number":["ZN5614"]}],"id":[{"id":"10.13039\/na","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2026,8,24]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>Biomolecular condensates formed by liquid\u2013liquid phase separation create dynamic, water-rich microenvironments that are essential for cellular organization, yet it is challenging to understand their internal aqueous phase. Here, we introduce Br\u00f8nsted photoacids and photobases as a new class of environmental fluorescent probes to interrogate the water phase inside biomolecular condensates. Using in vitro condensates formed by intrinsically disordered poly lysine or poly arginine peptides with nucleotides, we combine steady-state and time-resolved fluorescence to resolve the probe\u2019s excited-state proton transfer and subsequent proton recombination dynamics. We show that both photoacids and photobases remain largely solvated within poly lysine-based condensates, with only modest slowing of proton transfer relative to bulk water, consistent with a moderately more viscous aqueous environment. We mainly focus on photoacids, which exhibit strongly enhanced geminate proton recombination, attributed to nanometre-scale confinement of water within the condensates, inducing reflective boundaries for the dissociated proton. By modeling the recombination kinetics, we use the photoacid as a molecular ruler to estimate the dimensions of confined aqueous nanocavities, revealing characteristic maximum radii of \u223c6 nm. Altering condensate composition systematically modulates these properties, with ATP- and poly arginine\u2013based condensates displaying denser, less hydrated interiors. These findings establish excited-state proton transfer probes as powerful tools for quantifying nanoscale water confinement in biomolecular condensates, with implications for condensate function and molecular sequestration.<\/jats:p>","DOI":"10.1021\/jacsau.6c00873","type":"journal-article","created":{"date-parts":[[2026,7,17]],"date-time":"2026-07-17T18:38:23Z","timestamp":1784313503000},"page":"4740-4751","source":"Crossref","is-referenced-by-count":0,"title":["The Hidden Geometry\nof Water: Mapping Nanoscale Confinement\nand Water Properties Inside Peptide\u2013Nucleotide Biomolecular\nCondensates"],"prefix":"10.1021","volume":"6","author":[{"given":"Ayat","family":"Bdarneh","sequence":"first","affiliation":[{"name":"Technion\u2013Israel Institute of Technology , , ,","place":["Haifa, Israel, 3200003"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1543-5333","authenticated-orcid":true,"given":"Nadav","family":"Amdursky","sequence":"additional","affiliation":[{"name":"Technion\u2013Israel Institute of Technology , , ,","place":["Haifa, Israel, 3200003"]},{"name":"University of Sheffield , , ,","place":["Sheffield, U.K., S3 7HF"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"316","published-online":{"date-parts":[[2026,7,17]]},"reference":[{"key":"2026083023165018800_cit1","doi-asserted-by":"publisher","DOI":"10.1002\/mco2.223","article-title":"Biomolecular condensates: Formation\nmechanisms, biological functions, and therapeutic targets","volume":"4","author":"Niu","year":"2023","journal-title":"MedComm"},{"key":"2026083023165018800_cit2","doi-asserted-by":"publisher","first-page":"419","DOI":"10.1016\/j.cell.2018.12.035","article-title":"Considerations and Challenges in\nStudying Liquid-Liquid Phase Separation and Biomolecular Condensates","volume":"176","author":"Alberti","year":"2019","journal-title":"Cell"},{"key":"2026083023165018800_cit3","doi-asserted-by":"publisher","first-page":"420","DOI":"10.1016\/j.tcb.2018.02.004","article-title":"Protein Phase\nSeparation: A New Phase in Cell Biology","volume":"28","author":"Boeynaems","year":"2018","journal-title":"Trends\nCell Biol."},{"key":"2026083023165018800_cit4","doi-asserted-by":"publisher","first-page":"53","DOI":"10.1146\/annurev-physchem-071819-113553","article-title":"Biomolecular\nPhase Separation: From\nMolecular Driving Forces to Macroscopic Properties","volume":"71","author":"Dignon","year":"2020","journal-title":"Annu. Rev. Phys. Chem."},{"key":"2026083023165018800_cit5","doi-asserted-by":"publisher","first-page":"13238","DOI":"10.1073\/pnas.1917569117","article-title":"Liquid network\nconnectivity regulates the stability\nand composition of biomolecular condensates with many components","volume":"117","author":"Espinosa","year":"2020","journal-title":"Proc. Natl. Acad. Sci. U. S. A."},{"key":"2026083023165018800_cit6","doi-asserted-by":"publisher","first-page":"5892","DOI":"10.1038\/s41467-023-41586-y","article-title":"Thermodynamic forces from protein and water govern\ncondensate formation of an intrinsically disordered protein domain","volume":"14","author":"Mukherjee","year":"2023","journal-title":"Nat. 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Sci."},{"key":"2026083023165018800_cit42","doi-asserted-by":"publisher","first-page":"2443","DOI":"10.1073\/pnas.1812351116","article-title":"Exploring fast proton transfer events\nassociated with lateral proton diffusion on the surface of membranes","volume":"116","author":"Amdursky","year":"2019","journal-title":"Proc. Natl. Acad. Sci. U. S. A."},{"key":"2026083023165018800_cit43","doi-asserted-by":"publisher","first-page":"4200","DOI":"10.1016\/j.bpj.2024.07.002","article-title":"Proton diffusion on\nthe surface of mixed lipid membranes highlights the role of membrane\ncomposition","volume":"123","author":"Ramanthrikkovil Variyam","year":"2024","journal-title":"Biophys. 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Commun."},{"key":"2026083023165018800_cit50","doi-asserted-by":"publisher","first-page":"1118","DOI":"10.1038\/nchem.2803","article-title":"Phase behaviour\nof disordered proteins underlying low density and high permeability\nof liquid organelles","volume":"9","author":"Wei","year":"2017","journal-title":"Nat. Chem."},{"key":"2026083023165018800_cit51","doi-asserted-by":"publisher","first-page":"7647","DOI":"10.1039\/c3sm50726b","article-title":"Small-molecule\nuptake in membrane-free peptide\/nucleotide protocells","volume":"9","author":"Tang","year":"2013","journal-title":"Soft Matter"}],"container-title":["JACS Au"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/pubs.acs.org\/doi\/pdf\/10.1021\/jacsau.6c00873","content-type":"application\/pdf","content-version":"vor","intended-application":"unspecified"},{"URL":"https:\/\/pubs.acs.org\/jaaucr\/article-pdf\/6\/8\/4740\/66014370\/jacsau.6c00873.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"syndication"},{"URL":"https:\/\/pubs.acs.org\/jaaucr\/article-pdf\/6\/8\/4740\/66014370\/jacsau.6c00873.pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,8,31]],"date-time":"2026-08-31T03:17:26Z","timestamp":1788146246000},"score":1,"resource":{"primary":{"URL":"https:\/\/pubs.acs.org\/jaaucr\/article\/6\/8\/4740\/5214740\/The-Hidden-Geometry-of-Water-Mapping-Nanoscale"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,7,17]]},"references-count":51,"journal-issue":{"issue":"8","published-online":{"date-parts":[[2026,7,17]]},"published-print":{"date-parts":[[2026,8,24]]}},"URL":"https:\/\/doi.org\/10.1021\/jacsau.6c00873","relation":{},"ISSN":["2691-3704"],"issn-type":[{"value":"2691-3704","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,7,17]]}}}