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Controlling biomineralisation with cations


Production of polymers for controlling calcite growth is a well known approach for biomineralising organisms. Numerous studies show that polymers significantly influence CaCO3 growth rate and morphology but little is known about how the polymers are actually controlled by the organisms. Here we show that cations control the effect of the polysaccharides and that these processes have been in place for at least 60 million years. We studied the interaction between cleaved samples of pure calcite and ancient coccolith associated polysaccharides (aPS), that we had extracted from samples of Cretaceous chalk, in solutions that contained one of the common seawater cations, K+, Ca2+, Mg2+ and Sr2+. With atomic and chemical force microscopy (AFM and CFM), we showed that K+, Ca2+ and Sr2+ complex aPS through weak, outer sphere bonding, giving the aPS affinity for sites on steps and terraces. In contrast, Mg2+ enhanced formation of stronger and longer aPS complexes, resulting in low affinity for calcite terraces and strong affinity for steps. It is known that adsorption is influenced by ionic potential and ionic strength. Our results show that cation-polysaccharide complexing can modify the effectiveness of the polymer. Thus, creating organic molecules with cation complexing ability is quite an effective strategy for regulating mineral growth, both now and in the past.

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Publication details

The article was received on 05 Apr 2017, accepted on 12 Jun 2017 and first published on 13 Jun 2017

Article type: Paper
DOI: 10.1039/C7NR02424J
Citation: Nanoscale, 2017, Accepted Manuscript
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    Controlling biomineralisation with cations

    K. K. Sand, C. S. Pedersen, J. Matthiesen, S. Dobberschütz and S. Stipp, Nanoscale, 2017, Accepted Manuscript , DOI: 10.1039/C7NR02424J

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