How does iron interact with sporopollenin exine capsules? An X-ray absorption study including microfocus XANES and XRF imaging

Archibald, Stephen J.; Atkin, Stephen L.; Bras, Wim; Diego-Taboada, Alberto; Mackenzie, Grahame; Mosselmans, J. Frederick W.; Nikitenko, Sergey; Quinn, Paul D.; Thomas, Michael F.; Young, Nigel A.

Abstract

Sporopollenin exine capsules (SECs) derived from plant spores and pollen grains have been proposed as adsorption, remediation and drug delivery agents. Despite many studies there is scant structural data available. This X-ray absorption investigation represents the first direct structural data on the interaction of metals with SECs and allows elucidation of their structure–property relationships. Fe K-edge XANES and EXAFS data have shown that the iron local environment in SECs (derived from Lycopodium clavatum) reacted with aqueous ferric chloride solutions is similar to that of ferrihydrite (FeOOH) and by implication ferritin. Fe Kα XRF micro-focus experiments show that there is a poor correlation between the iron distribution and the underlying SEC structure indicating that the SEC is coated in the FeOOH material. In contrast, the Fe Kα XRF micro-focus experiments on SECs reacted with aqueous ferrous chloride solutions show that there is a very high correlation between the iron distribution and the SEC structure, indicating a much more specific form of interaction of the iron with the SEC surface functional groups. Fe K-edge XANES and EXAFS data show that the FeII can be easily oxidised to give a structure similar to, but not identical to that in the FeIII case, and that even if anaerobic conditions are used there is still partial oxidation to FeIII.

Citation

Archibald, S. J., Atkin, S. L., Bras, W., Diego-Taboada, A., Mackenzie, G., Mosselmans, J. F. W., Nikitenko, S., Quinn, P. D., Thomas, M. F., & Young, N. A. (2014). How does iron interact with sporopollenin exine capsules? An X-ray absorption study including microfocus XANES and XRF imaging. Journal of Materials Chemistry B, 2(8), 945-959. https://doi.org/10.1039/c3tb21523g

• Acceptance Date: Dec 17, 2013
• Publication Date: Feb 28, 2014
• Deposit Date: Aug 28, 2015
• Publicly Available Date: Nov 23, 2017
• Journal: Journal of materials chemistry. B
• Print ISSN: 2050-750X
• Electronic ISSN: 2050-7518
• Publisher: Royal Society of Chemistry
• Peer Reviewed: Peer Reviewed
• Volume: 2
• Issue: 8
• Pages: 945-959
• DOI: https://doi.org/10.1039/c3tb21523g
• Keywords: Sporopollenin exine capsules, Iron, X-ray absorption, XANES, XRF
• Public URL: https://hull-repository.worktribe.com/output/378265
• Publisher URL: http://pubs.rsc.org/en/content/articlelanding/2014/tb/c3tb21523g#!divAbstract
• Additional Information: Authors' accepted manuscript of article of article published in: Journal of materials chemistry. B, 2014, issue 8
• Contract Date: Nov 23, 2017