Complete chemical and structural characterization of selenium-incorporated hydroxyapatite

Baris Alkan,Caner Durucan

doi:10.1007/s10856-021-06631-6

Baris Alkan, Caner Durucan

Open Access

https://doi.org/10.1007/s10856-021-06631-6

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Abstract

Hydroxyapatite (HAp) has long been used as synthetic bone tissue replacement material. Recent advances in this area have led to development of dual-functional bioceramics exhibiting high biocompability/osteoconductivity together with the therapeutic effect. Selenium, in that respect, is an effective therapeutic agent with promising antioxidant activity and anticancer effects. In this study, selenium-incorporated hydroxyapatite (HAp:Se) particles have been synthesized by modified aqueous precipitation method using calcium (Ca(NO3)2·4H2O) and phosphate ((NH4)2HPO4) salts and sodium selenite (Na2SeO3). The effects of selenium incorporation and post-synthesis calcination treatment (900–1100 °C) on physical, chemical properties and crystal structure of resultant HAp powders have been investigated. Complete chemical identification was performed with spectroscopical analyses including Fourier transform infrared and x-ray photoelectron spectroscopy to elucidate the mechanism and chemical nature of selenium incorporation in HAp. Meanwhile, detailed x-ray diffraction studies by Rietveld refinement have conducted to explain changes in the HAp crystal structure upon selenium incorporation.

Highlights

Calcium phosphates such as hydroxyapatite (Ca10(PO4)6(OH)2 or HAp) and calcium-deficient hydroxyapatite (Ca(10−x) (HPO4)x(PO4)(6−x)(OH)(2−x) or CDHAp) have been widely used as hard tissue analogs due to their chemical similarity with natural bone mineral, as well as due to their superior bioactivity and osteoconductivity [1,2,3,4,5,6]
The ionic species of selenium, in this regard, are critically important since they constitute of selenoproteins which are essential to the immune system with their antioxidant function, and serve as catalyst in production of active thyroid hormone, and leading to cell proliferation [10]
Ultrapure deionized (DI) water was used in all experiments

Summary

Introduction

Calcium phosphates such as hydroxyapatite (Ca10(PO4)6(OH) or HAp) and calcium-deficient hydroxyapatite (Ca(10−x) (HPO4)x(PO4)(6−x)(OH)(2−x) or CDHAp) have been widely used as hard tissue analogs due to their chemical similarity with natural bone mineral, as well as due to their superior bioactivity and osteoconductivity [1,2,3,4,5,6]. Composed of calcium and phosphate the natural bone mineral is a reservoir for various ionic species including sodium, magnesium, zinc, fluorine, carbonates etc. The ionic species of selenium, in this regard, are critically important since they constitute of selenoproteins which are essential to the immune system with their antioxidant function, and serve as catalyst in production of active thyroid hormone, and leading to cell proliferation [10]

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