The Carbonate and Sodium Environments in Precipitated and Biomimetic Calcium Hydroxy-Carbonate Apatite Contrasted with Bone Mineral: Structural Insights from Solid-State NMR

Ozlen F Yasar,Renny Mathew,Yihong Liu,Baltzar Stevensson,Yang Yu,Wei-Chih Liao,Mattias Edén,Zhijian Shen

doi:10.1021/acs.jpcc.0c11389

Ozlen F Yasar, Renny Mathew + Show 6 more

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https://doi.org/10.1021/acs.jpcc.0c11389

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Abstract

Bone mineral consists of calcium hydroxy-carbonate apatite (HCA) that incorporates other minor cation substituents, primarily Na+ (0.5–0.8 wt %). We examine the carbonate species in various HCA spe...

Highlights

Bone and dentin comprise calcium phosphate (CaP) mineral (≈65 wt %) deposited on fibrils of type I collagen (≈25 wt %),[1−3] whereas dental enamel contains only ≈1 wt % of organic matter.[3]
Dentin, and enamel mineral consists of CO32−-bearing calcium hydroxyapatite (HA; Ca5(PO4)3OH),[1−3] referred to as calcium hydroxycarbonate apatite (HCA)
We demonstrate the selective detection of the CO32− anions by magic-angle spinning (MAS) nuclear magnetic resonance (NMR) from intact bone samples and discuss their 13C chemical shifts

Summary

Introduction

Bone and dentin (inner tooth domain) comprise calcium phosphate (CaP) mineral (≈65 wt %) deposited on fibrils of type I collagen (≈25 wt %),[1−3] whereas dental enamel contains only ≈1 wt % of organic matter.[3] Bone, dentin, and enamel mineral consists of CO32−-bearing calcium hydroxyapatite (HA; Ca5(PO4)3OH),[1−3] referred to as calcium hydroxycarbonate apatite (HCA). Bone/dentin-mineral particles constitute very thin (1.5−10 nm1,2) platelets packed like a deck of cards.[1,2,4] The CO32− content of bone elevates during its aging and amounts to 4−8 wt % in mature mineral,[5−7] whereas dental enamel only comprises 2.0−4.5 wt %.8,9. Bone/dentin-mineral particles constitute very thin (1.5−10 nm1,2) platelets packed like a deck of cards.[1,2,4] The CO32− content of bone elevates during its aging and amounts to 4−8 wt % in mature mineral,[5−7] whereas dental enamel only comprises 2.0−4.5 wt %.8,9 For synthetic HCA, it is well documented that the increased CO32− incorporation leads to a size-reduction of the crystallites,[10−16] thereby increasing their solubility.[16,17] such size/solubility relationships

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