He Kun, Sawczyk Michal, Liu Cong, Yuan Yifei, Song Boao, Deivanayagam Ram, Nie Anmin, Hu Xiaobing, Dravid Vinayak P, Lu Jun, Sukotjo Cortino, Lu Yu-Peng, Král Petr, Shokuhfar Tolou, Shahbazian-Yassar Reza
Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, IL 60607, USA.
Northwestern University Atomic and Nanoscale Characterization Experimental (NUANCE) Center, Northwestern University, Evanston, IL 60208, USA.
Sci Adv. 2020 Nov 18;6(47). doi: 10.1126/sciadv.aaz7524. Print 2020 Nov.
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.
为了治疗硬组织损伤或克服软组织中的病理性钙化，需要详细了解磷酸钙材料的矿化途径。在此，我们通过原位液体池透射电子显微镜（TEM）报告了在人工唾液溶液中羟基磷灰石（HA）矿化途径的详细机理研究。研究发现，HA的矿化始于在唾液溶液中形成富离子和贫离子溶液，随后经典成核过程和非经典成核过程共存。对于非经典途径，无定形磷酸钙（ACP）作为HA在ACP表面成核的底物，而经典途径的特征是从溶液中直接形成HA晶核。HA晶体在ACP表面的生长伴随着ACP的溶解过程。这项工作中报道的发现对于理解HA矿物质的生理和病理形成，以及设计用于骨愈合和硬组织修复的生物矿化过程具有重要意义。
