In Vitro Dissolution of Na-Ca-P-Oxynitrides.

Natalia Anna Wójcik,Bo Jonson,Leena Hupa,Sharafat Ali,Polina Sinitsyna

doi:10.3390/ma14237425

Abstract

Sodium-calcium-phosphate based oxynitride glasses and glass-ceramics doped with Mg, Si, and Nb were studied in vitro in simulated body fluid (SBF) under static conditions. The release of ions and pH changes up to 7 days of immersion were investigated. The nitrogen incorporation into phosphate glass matrix was found to notably influence in vitro dissolution only of homogenous glasses. Increasing the nitrogen content in the samples decreased the mean mass loss, while the niobate incorporation increased it. The correlation between the nitrogen content and increase in pH of SBF was also observed. The presence of phosphates crystallites was found to support the dissolution process at the beginning step (up to 3 days).

Highlights

IntroductionCongenital abnormalities, traumatic injury, and/or disease might damage the human bone
Besides the changes that occurred on the glass surface, the changes that proceeded in the solution should be studied to fully describe the dissolution of bioactive glasses
In vitro dissolution tests in simulated body fluid (SBF) were conducted for 12 samples

Summary

Introduction

Congenital abnormalities, traumatic injury, and/or disease might damage the human bone. Bone is one of the most commonly transplanted tissues [1]. Synthetic materials such as bioactive glasses and glass-ceramic composites are frequently studied as implant materials for bone replacement [2–6]. These materials can chemically bond with the bone and potentially enhance new bone growth used to replace damaged bone. When exposed to body fluids, an amorphous calcium phosphate layer forms at the glass surface. This layer crystallizes into bio-mimetic hydroxyapatite (HAp, Ca10 (PO4 ) (OH)2 ) that provides a bone-glass interface [11]. The in vitro dissolution experiments are carried out in aqueous solutions (simulated body fluid–SBF, phosphate buffered solution–PBS and Tris-buffered solution) under static conditions, which allows to analyze the pH changes during immersion [12–14]

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