Small organic molecules containing amorphous calcium phosphate: synthesis, characterization and transformation

Abhishek Indurkar; Pawan Kudale; Vitālijs Rjabovs; Ivo Heinmaa; Öznur Demir; Matvejs Kirejevs; Kristaps Rubenis; Ganesh Chaturbhuj; Māris Turks; Janis Locs

doi:10.3389/fbioe.2023.1329752

Small organic molecules containing amorphous calcium phosphate: synthesis, characterization and transformation

Front Bioeng Biotechnol. 2024 Jan 12:11:1329752. doi: 10.3389/fbioe.2023.1329752. eCollection 2023.

Authors

Abhishek Indurkar^{1

2}, Pawan Kudale³, Vitālijs Rjabovs⁴, Ivo Heinmaa⁵, Öznur Demir^{1

2}, Matvejs Kirejevs¹, Kristaps Rubenis^{1

2}, Ganesh Chaturbhuj³, Māris Turks⁴, Janis Locs^{1

2}

Affiliations

¹ Rudolfs Cimdins Riga Biomaterials Innovations and Development Centre of RTU, Institute of General Chemical Engineering, Faculty of Materials Science and Applied Chemistry, Riga Technical University, Riga, Latvia.
² Baltic Biomaterials Centre of Excellence, Headquarters at Riga Technical University, Riga, Latvia.
³ Department of Pharmaceutical Sciences and Technology, Institute of Chemical Technology, Mumbai, India.
⁴ Institute of Technology of Organic Chemistry, Faculty of Materials Science and Applied Chemistry, Riga Technical University, Riga, Latvia.
⁵ National Institute of Chemical Physics and Biophysics, Tallinn, Estonia.

Abstract

As the primary solid phase, amorphous calcium phosphate (ACP) is a pivotal precursor in cellular biomineralization. The intrinsic interplay between ACP and Howard factor underscores the significance of understanding their association for advancing biomimetic ACP development. While organic compounds play established roles in biomineralization, this study presents the synthesis of ACP with naturally occurring organic compounds (ascorbate, glutamate, and itaconate) ubiquitously found in mitochondria and vital for bone remodeling and healing. The developed ACP with organic compounds was meticulously characterized using XRD, FTIR, and solid-state ¹³C and ³¹P NMR. The morphological analysis revealed the characteristic spherical morphology with particle size close to 20 nm of all synthesized ACP variants. Notably, the type of organic compound strongly influences true density, specific surface area, particle size, and transformation. The in vitro analysis was performed with MC3T3-E1 cells, indicating the highest cell viability with ACP_ASC (ascorbate), followed by ACP_ITA (itaconate). The lowest cell viability was observed with 10 %w/v of ACP_GLU (glutamate); however, 1 %w/v of ACP_GLU was cytocompatible. Further, the effect of small organic molecules on the transformation of ACP to low crystalline apatite (Ap) was examined in Milli-Q^® water, PBS, and α-MEM.

Keywords: amorphous calcium phosphate; ascorbate; biomaterials; biomimetics; bone tissue engineering; glutamate; itaconate; organic compounds.

Grants and funding

The author(s) declare financial support was received for the research, authorship, and/or publication of this article. The authors acknowledge financial support from the European Union’ Horizon 2020 research and innovation program under grant agreement No. 857287 (BBCE) and Baltic Research Programme Project No. EEA-RESEARCH-85“Waste-to-resource: eggshells as a source for next-generation biomaterials for bone regeneration (EGGSHELL)” under the EEA Grant of Iceland, Liechtenstein and Norway No. EEZ/BPP/VIAA/2021/1. The authors are grateful for generous funding from the Mahatma Jyotiba Phule Research Fellowship, Govt. of Maharashtra, India (MAHAJYOTI/2022/PhD Fellowship/1002(624)).