Revealing nanoscale mineralization pathways of hydroxyapatite using in situ liquid cell transmission electron microscopy

Kun He; Michal Sawczyk; Cong Liu; Yifei Yuan; Boao Song; Ram Deivanayagam; Anmin Nie; Xiaobing Hu; Vinayak P Dravid; Jun Lu; Cortino Sukotjo; Yu-Peng Lu; Petr Král; Tolou Shokuhfar; Reza Shahbazian-Yassar

doi:10.1126/sciadv.aaz7524

Revealing nanoscale mineralization pathways of hydroxyapatite using in situ liquid cell transmission electron microscopy

Sci Adv. 2020 Nov 18;6(47):eaaz7524. doi: 10.1126/sciadv.aaz7524. Print 2020 Nov.

Authors

Kun He^{1 2 3}, Michal Sawczyk⁴, Cong Liu⁵, Yifei Yuan^{1 5}, Boao Song¹, Ram Deivanayagam¹, Anmin Nie⁶, Xiaobing Hu², Vinayak P Dravid², Jun Lu⁵, Cortino Sukotjo⁷, Yu-Peng Lu⁸, Petr Král^{9 10}, Tolou Shokuhfar^{11 12}, Reza Shahbazian-Yassar¹¹

Affiliations

¹ Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, IL 60607, USA.
² Northwestern University Atomic and Nanoscale Characterization Experimental (NUANCE) Center, Northwestern University, Evanston, IL 60208, USA.
³ School of Materials Science and Engineering, Shandong University, Ji'nan 250061, China.
⁴ Department of Chemistry, University of Illinois at Chicago, Chicago, IL 60607, USA.
⁵ Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, IL 60439, USA.
⁶ State Key Lab of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004, China.
⁷ Department of Restorative Dentistry, College of Dentistry, University of Illinois at Chicago, Chicago, IL 60612, USA.
⁸ School of Materials Science and Engineering, Shandong University, Ji'nan 250061, China. rsyassar@uic.edu tolou@uic.edu biosdu@sdu.edu.cn pkral@uic.edu.
⁹ Department of Chemistry, University of Illinois at Chicago, Chicago, IL 60607, USA. rsyassar@uic.edu tolou@uic.edu biosdu@sdu.edu.cn pkral@uic.edu.
¹⁰ Departments of Physics, Biopharmaceutical Sciences, and Chemical Engineering, University of Illinois at Chicago, 845 West Taylor Street, Chicago, IL 60607, USA.
¹¹ Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, IL 60607, USA. rsyassar@uic.edu tolou@uic.edu biosdu@sdu.edu.cn pkral@uic.edu.
¹² Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA.

Abstract

To treat impairments in hard tissues or overcome pathological calcification in soft tissues, a detailed understanding of mineralization pathways of calcium phosphate materials is needed. Here, we report a detailed mechanistic study of hydroxyapatite (HA) mineralization pathways in an artificial saliva solution via in situ liquid cell transmission electron microscopy (TEM). It is found that the mineralization of HA starts by forming ion-rich and ion-poor solutions in the saliva solution, followed by coexistence of the classical and nonclassical nucleation processes. For the nonclassical path, amorphous calcium phosphate (ACP) functions as the substrate for HA nucleation on the ACP surface, while the classical path features direct HA nucleation from the solution. The growth of HA crystals on the surface of ACP is accompanied by the ACP dissolution process. The discoveries reported in this work are important to understand the physiological and pathological formation of HA minerals, as well as to engineer the biomineralization process for bone healing and hard tissue repairs.

Copyright © 2020 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC).

Publication types

Research Support, Non-U.S. Gov't