Centers and Institutes
Published December 19, 2024 | Version v1
Journal article Open

Lanthanide binding peptide surfactants at air–aqueous interfaces for interfacial separation of rare earth elements

Creators

  • 1. The City College of New York
  • 2. Northwestern University
  • 3. University of Pennsylvania
  • 4. University of Illinois at Chicago
  • 5. University of Chicago

Description

Rare earth elements (REEs) are critical materials to modern technologies. They are obtained by selective separation from mining feedstocks consisting of mixtures of their trivalent cation. We are developing an all-aqueous, bioinspired, interfacial separation using peptides as amphiphilic molecular extractants. Lanthanide binding tags (LBTs) are amphiphilic peptide sequences based on the EF-hand metal binding loops of calcium-binding proteins which complex selectively REEs. We study LBTs optimized for coordination to Tb3+ using luminescence spectroscopy, surface tensiometry, X-ray reflectivity, and X-ray fluorescence near total reflection, and find that these LBTs capture Tb3+ in bulk and adsorb the complex to the interface. Molecular dynamics show that the binding pocket remains intact upon adsorption. We find that, if the net negative charge on the peptide results in a negatively charged complex, excess cations are recruited to the interface by nonselective Coulombic interactions that compromise selective REE capture. If, however, the net negative charge on the peptide is −3, resulting in a neutral complex, a 1:1 surface ratio of cation to peptide is achieved. Surface adsorption of the neutral peptide complexes from an equimolar mixture of Tb3+ and La3+ demonstrates a switchable platform dictated by bulk and interfacial effects. The adsorption layer becomes enriched in the favored Tb3+ when the bulk peptide is saturated, but selective to La3+ for undersaturation due to a higher surface activity of the La3+ complex.

Data availability

All study data are included in the article and/or SI Appendix.

Files

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Additional details

Identifiers

DOI
10.1073/pnas.2411763121
Other
oai:uchicago.tind.io:14371

Funding

U.S. Department of Energy
DE-SC0022240
National Science Foundation
CHE- 1834750
National Science Foundation
CHE-2335833
U.S. Department of Energy
DE-AC02-06CH11357
National Institutes of Health
S10 OD030460

UChicago Information

Division(s)
Pritzker School of Molecular Engineering
Center(s) or Institute(s)
Center for Advanced Radiation Sources