The Synergistic Effect Between Acidic Carboxylic and Basic Amino Molecules in Chiral Hierarchical Suprastructure of Calcium Carbonate

Abstract

Proteins play a crucial role in the formation of biominerals through their amino acid residues. Although the functions of acidic amino acid residues in this process are well-documented, the contributions of basic amino acid residues remain poorly understood. Here, we reveal a synergistic effect between acidic amino acid aspartic acid (Asp) and basic amino acid lysine (Lys) in the formation of chiral hierarchical suprastructured vaterite helicoids. Specifically, acidic Asp governs the development of the chiral hierarchical suprastructure, while basic Lys effectively modulates the mineral phase and enhances the crystallization dynamic of the helicoids. Notably, this synergistic effect is not limited to specific amino acids but can be generalized to other carboxylic and amino molecules. We propose that the differential regulations of calcium carbonate crystallization by the negatively charged acidic carboxylic and positively charged basic amino molecules stem from their distinct influences on the surface charge and interfacial energy of calcium carbonate. These findings can advance our understanding of how mineralization proteins utilize their diverse amino acid residues to direct biomineral formation. Moreover, this study may offer insights into the design and synthesis of advanced functional materials with chiral hierarchical suprastructures.