The Science

Mimicking the ability of marine organisms, such as corals, to create calcium carbonate (CaCO₃) represents a potential mechanism for energy-efficient carbon dioxide (CO₂) removal from the environment. Researchers explored how to use peptoids, synthetic molecules that mimic naturally occurring peptides, to promote carbonate mineralization. They identified how peptoid interactions with a calcite surface and solvated growth species alter crystal growth processes. The team found that the peptoids alter the structure of the mineral surface and the overlying solution and increase the reaction rates of ions in solution, resulting in faster mineralization.

The Impact

The extensive deposits of CaCO₃ generated by marine organisms constitute the largest and oldest CO₂ reservoir on Earth. These organisms use macromolecules like peptides and proteins to create carbonate minerals, effectively removing CO₂ from the environment. By understanding how biomimetic molecules alter the carbonate mineralization process, researchers can develop a set of principles to design materials and structures that enable more effective mineralization.

Summary

Marine organisms create CaCO₃ in part from CO₂ found in the atmosphere. This mineralization process represents an avenue for highly stable long-term carbon sequestration, inspired by biology. However, the molecular mechanisms behind the mineralization are largely unknown.

Researchers explored how peptoids, a class of sequence-defined peptide mimetics, could accelerate calcite growth. The peptoid design was inspired by the chemistries of the proteins and peptides involved in natural biological carbonate mineralization. The synthesized peptoids have a diblock structure of hydrophobic and charged hydrophilic groups, which are highly effective in accelerating calcite growth. The peptoids can facilitate HCO₃⁻ deprotonation and Ca²⁺ desolvation as well as disrupt the calcite surface hydration structure, thereby lowering the energy barrier for ion attachment and promoting calcite crystal growth. These results provide predictive design principles that can be used to improve efficiency and sustainability in various applications, including CO₂ sequestration and other energy-related applications, improving both efficiency and sustainability.

Contact

Chun-Long Chen, Pacific Northwest National Laboratory, Chunlong.Chen@pnnl.gov

Funding

This work was mainly supported by the Department of Energy (DOE), Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division, Biomolecular Materials program under award FWP 80124 at Pacific Northwest National Laboratory (PNNL). Isothermal titration calorimetry measurements were conducted at the Molecular Foundry of Lawrence Berkeley National Laboratory, which was supported by the Office of Science (No. DE-AC02-05CH11231). PNNL is a multi-program national laboratory operated for DOE by Battelle under Contract No. DE-AC05-76RL01830.