Hydrogels find their inner magnetism

Subjects Magnetic materialsMagnetic properties and materials Hydrogels containing C=O groups and calcium cations show an unexpected paramagnetic effect that may have biomedical applications. Access through your institution Buy or subscribe This is a preview of subscription content, access via your institution Access options Access through your institution Access Nature and 54 other Nature Portfolio journals Get Nature+, our best-value online-access subscription $32.99 / 30 days cancel any time Learn more Subscribe to this journal Receive 12 print issues and online access $259.00 per year only $21.58 per issue Learn more Rent or buy this article Prices vary by article type from$1.95 to$39.95 Learn more Prices may be subject to local taxes which are calculated during checkout Fig. 1: Calcium ions interacting with the carbonyl group on calcium alginate. ReferencesKhan, S., Ullah, A., Ullah, K. & Rehman, N. Des. Monomers Polym. 19, 456–478 (2016).Article CAS Google Scholar Wichterie, O. & Lim, D. Nature 185, 117–118 (1960).Article Google Scholar Lim, F. & Sun, A. M. Science 210, 908–910 (1980).Article CAS PubMed Google Scholar Green, J. J. & Elisseeff, J. H. Nature 540, 386–394 (2016).Article CAS PubMed PubMed Central Google Scholar Heisenberg, W. Z. Phys. 49, 619–636 (1928).CAS Google Scholar Tamura, M. et al. Chem. Phys. Lett. 186, 401–404 (1991).Article CAS Google Scholar Blundell, S. J. & Pratt, F. L. J. Phys. Condens. Matter 16, R771–R828 (2004).Article CAS Google Scholar Londhe, P. V. et al. Coord. Chem. Rev. 522, 216228 (2025).Article CAS Google Scholar Chen, R. et al. Nat. Mater. https://doi.org/10.1038/s41563-025-02477-3 (2026).Article PubMed Google Scholar Wahsner, J., Gale, E. M., Rodríguez-Rodríguez, A. & Caravan, P. Chem. Rev. 119, 957–1057 (2019).Article CAS PubMed Google Scholar Download referencesAuthor informationAuthors and AffiliationsDepartment of Physics, University of Oxford, Oxford, UKStephen J. BlundellAuthorsStephen J. BlundellView author publicationsSearch author on:PubMed Google ScholarCorresponding authorCorrespondence to Stephen J. Blundell.Ethics declarations Competing interests The author declares no competing interests. Rights and permissionsReprints and permissionsAbout this articleCite this articleBlundell, S.J. Hydrogels find their inner magnetism. Nat. Mater. (2026). https://doi.org/10.1038/s41563-026-02572-zDownload citationPublished: 03 April 2026Version of record: 03 April 2026DOI: https://doi.org/10.1038/s41563-026-02572-zShare this articleAnyone you share the following link with will be able to read this content:Get shareable linkSorry, a shareable link is not currently available for this article.Copy shareable link to clipboard Provided by the Springer Nature SharedIt content-sharing initiative Unexpected strong paramagnetism of hydrogels containing carbon–oxygen double bonds induced by calcium cations Ruoyang ChenYue-Yu ZhangHaiping Fang Nature Materials Article 28 Jan 2026