The Influence of Different Classes of Amino Acids on Calcium Phosphates Seeded Growth

Abstract

Amino acids (AAs) attract attention for elucidating the role of proteins in biomineralization and the preparation of functionalized biomaterials. The influence that AAs exert on calcium phosphate (CaP) mineralization is still not completely understood, as contradictory results have been reported. In this paper, the influence of the addition of different classes of AAs, charged (L-aspartic acid, Asp; L-lysine, Lys), polar (L-asparagine, Asn; L-serine, Ser; L-tyrosine, Tyr), and non-polar (L-phenylalanine, Phe), on CaP growth in the presence of octacalcium phosphate (OCP) and calcium hydrogenphosphate dihydrate (DCPD) seeds was investigated. In control systems (without AAs), a calcium-deficient apatite (CaDHA) layer was formed on the surface of OCP, while a mixture of CaDHA and OCP in the form of spherical aggregates was formed on the surface of DCPD crystals. Charged and non-polar promoted, while polar AAs inhibited CaDHA formation on the OCP seeds. In the case of DCPD, Lys, Asp, and Phe promoted CaP formation, while the influence of other AAs was negligible. The most efficient promotor of precipitation in both cases was non-polar Phe. No significant influence of AAs on the composition and morphology of precipitates was observed. The obtained results are of interest for understanding biomineralization processes and additive controlled material synthesis.

Comparison of the Effect of the Amino Acids on Spontaneous Formation and Transformation of Calcium Phosphates

“…On the other hand, Ser present at low concentrations (up to 0.07 mmol dm −3 ) did not influence induction time [30]. In our recent study, we investigated the influence of different classes of amino acids on CaPs' seeded growth [52]. In the case of OCP-seeded crystals, Ser was the most efficient inhibitor, while Phe was the most efficient promotor of CaP formation, similar to the behavior observed in this study.…”

“…AAs can either decrease the solution supersaturation through the complexation of calcium or phosphate ions or they can interact with the solid phase by non-specific adsorption at surfaces or at growing sites [20][21][22][23][24][25], which both intuitively lead to inhibition [18]. It should be noted that the AAs affinity towards the solid phases, which appear in biomineralization, is influenced by the overall charge and the charge of specific AAs segments, their ability to form chemical bonds, and their stereochemical or geometrical properties [18,20,21,31,[50][51][52]. In addition to the complexity in the mechanism of action, the reason for contradictory results also lies in the fact that the employed experimental conditions (reactant concentration, temperature, mode of mixing) and experimental setup (seeded growth, constant composition, spontaneous precipitation) vary considerably between different studies.…”

Role of carboxylic organic molecules in interfibrillar collagen mineralization

“…In the past 20 years, the research is focused on finding the role of carboxylic compounds in interfibrillar collagen mineralization ( Ikawa et al, 2008 ; Sakamoto et al, 2008 ; Ishikawa and Oaki, 2014 ; Josipović et al, 2020 ; Veiga et al, 2020 ; Wang et al, 2020 ). Recent studies have also provided new findings such as A) Influence of carboxylic ions in the conversion of ACP to OCP ( Sugiura et al, 2015 ).…”