Tuning calcite morphology and growth acceleration by a rational design of highly stable protein-mimetics

Abstract

In nature, proteins play a significant role in biomineral formation. One of the ultimate goals of bioinspired materials science is to develop highly stable synthetic molecules that mimic the function of these natural proteins by controlling crystal formation. Here, we demonstrate that both the morphology and the degree of acceleration or inhibition observed during growth of calcite in the presence of peptoids can be rationally tuned by balancing the electrostatic and hydrophobic interactions, with hydrophobic interactions playing the dominant role. While either strong electrostatic or hydrophobic interactions inhibit growth and reduces expression of the {104} faces, correlations between peptoid-crystal binding energies and observed changes in calcite growth indicate moderate electrostatic interactions allow peptoids to weakly adsorb while moderate hydrophobic interactions cause disruption of surface-adsorbed water layers, leading to growth acceleration with retained expression of the {104} faces. This study provides fundamental principles for designing peptoids as crystallization promoters, and offers a straightforward screening method based on macroscopic crystal morphology. Because peptoids are sequence-specific, highly stable, and easily synthesized, peptoid-enhanced crystallization offers a broad range of potential applications.

The role of macromolecules in the formation of kidney stones

“…The non-ionic amino acids apparently have little effect on protein-crystal interactions beyond dilution of the effect of the strongly interacting anionic groups or spatial separation of charged groups along the primary sequence, though one publication showed the hydrogen bonding, non-ionic amino acids like serine could enhance surface interactions compared to other non-ionic amino acids [83] . Also, hydrophobic interactions at crystal surfaces have been suggested to play an important role in growth acceleration based on data in calcite (calcium carbonate) [84] . While modeling the complexity of the mixture of hundreds of urinary proteins is beyond our current level of understanding of protein-crystal interactions, numerous studies have revealed that the mixture of proteins from normal individuals inhibits growth and aggregation of COM crystals, consistent with net anionic character of the protein mixtures [85] .…”

Using Biomimetic Polymers in Place of Noncollagenous Proteins to Achieve Functional Remineralization of Dentin Tissues

“…Peptoids also exhibit potent biological functionalities and are biocompatible 27–29 . In a recent study 30–31 , dramatic modifications of CaCO 3 crystal growth rate and morphology by peptoids highlighted the potential of using these polymers for biomimetic approaches to controlling mineralization and remineralization. Here, we showed peptoids’ potency to guide and modulate HAP mineralization on collagen substrates.…”

Microscopic Studies of Calcium Sulfate Crystallization and Transformation at Aqueous–Organic Interfaces

“…The discovery of simple, low-energy pathways for the growth of highly desirable and unstable polymorphs with vital industrial and biological applications is particularly important. [1][2][3][4][5][6][7][8][9][10] Numerous examples of high level control over polymorphism have been established for both organic [1][2][3] and inorganic [4][5][6][7][8] crystal systems. In particular, the calcium carbonate crystal system has been extensively studied.…”

“…In particular, the calcium carbonate crystal system has been extensively studied. [4][5][6][7]9,10 Crystal growth additives such as natural proteinmimics 4,10 and polymers [5][6][7] are commonly used to achieve the growth of the metastable polymorphs, vaterite and aragonite, at much lower temperatures than otherwise possible.…”