Peptoid-enhanced Mineralization of CaCO3 for CO2 sequestration

Peptoids, or poly-N-substituted glycines, are a novel class of non-natural polymers recently developed to mimic both structures and functionalities of peptides and proteins, and bridge the gap between biopolymers and bulk polymers. As with peptides, sequence-specific peptoids can be efficiently synthesized by using automated solid-phase synthesis starting from a large number of chemically diverse amine building blocks. Moreover, peptoids exhibit much higher protease stability and thermal stability than peptides or proteins. In nature, proteins are known to play significant roles in the control of nucleation and growth of various minerals. Inspired by recent research that showed low concentrations of acidic peptides and proteins can significantly accelerate calcite growth, we designed and synthesized a suite of peptoids and screened them for control over calcite morphology and growth rate. Results to date demonstrate a both high degree of morphological control and extreme levels of acceleration. Crystal shapes ranging from elongated spindles and twisted paddles to crosses and spheres were generated, and one 12-meric amphiphilic peptoid increased calcite growth rates by nearly 2300% at a concentration of only 50 nM. Correlations between growth control and peptoid characteristics such as structural sequence and amphiphilicity will be discussed.