Single molecule investigation of the onset and minimum size of the calcium-mediated junction zone in alginate

Bowman, Kate A., Aarstad, Olav Andreas, Nakamura, Marcela, Stokke, Bjørn Torger, Skjåk-Bræk, Gudmund and Round, Andrew N. ORCID: (2016) Single molecule investigation of the onset and minimum size of the calcium-mediated junction zone in alginate. Carbohydrate Polymers, 148. pp. 52-60. ISSN 0144-8617

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One of the principal roles of alginate, both natively and in commercial applications, is gelation via Ca2+-mediated crosslinks between blocks of guluronic acid. In this work, single molecule measurements were carried out between well-characterised series of nearly monodisperse guluronic acid blocks (‘oligoGs’) using dynamic force spectroscopy. The measurements provide evidence that for interaction times on the order of tens of milliseconds the maximum crosslink strength is achieved by pairs of oligoGs long enough to allow the coordination of 4 Ca2+ ions, with both shorter and longer oligomers forming weaker links. Extending the interaction time from tens to hundreds of milliseconds allows longer oligoGs to achieve much stronger crosslinks but does not change the strength of individual links between shorter oligoGs. These results are considered in light of extant models for the onset of cooperative crosslinking in polyelectrolytes and an anisotropic distribution of oligoGs on interacting surfaces and provide a timescale for the formation and relaxation of alginate gels at the single crosslink level.

Item Type: Article
Uncontrolled Keywords: alginate,gel,junction zone,single molecule,afm
Faculty \ School: Faculty of Science > School of Pharmacy
UEA Research Groups: Faculty of Science > Research Groups > Drug Delivery and Pharmaceutical Materials (former - to 2017)
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Depositing User: Pure Connector
Date Deposited: 22 Apr 2016 09:00
Last Modified: 22 Oct 2022 01:03
DOI: 10.1016/j.carbpol.2016.04.043


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