Synthesis and Characterization of Novel Calcium-Silicate Nanobioceramics with Magnesium: Effect of Heat Treatment on Biological, Physical and Chemical Properties

Konstantina Kazeli,Lamprini Malletzidou,Lambrini Papadopoulou,Konstantinos Chrissafis,Eleana Kontonasaki,Eleni Likotrafiti,Jonathan Rhoades,Anna Theocharidou,Georgia K Pouroutzidou,Theodoros Lialiaris,Evgenia Lymperaki,Ioannis Tsamesidis

doi:10.3390/ceramics4040045

Abstract

Glass-ceramic nanopowder with a composition of 55SiO2-35CaO-10MgO (mol %) was synthesized by the sol–gel method and was heat treated at three temperatures (T1 = 835 °C, T2 = 1000 °C, T3 = 1100 °C) in order to obtain different materials (C1, C2, C3, respectively) varying in crystal structure. Bioactivity and oxidative stress were evaluated in simulated body fluid (SBF) for various time periods (up to 10 days). The structure of the synthesized materials and their apatite-forming ability were investigated by X-ray diffractometry (XRD), Fourier transform infrared spectroscopy (FTIR), Scanning Electron Microscopy and Energy Dispersive Spectroscopy (SEM/EDS). The antibacterial properties of the synthesized materials were evaluated against three Gram-positive and four Gram-negative bacterial strains and their biocompatibility was verified on a primary cell line of human gingival fibroblasts (HGFs) by the MTT (3-[4, 5-dimethylthiazol-2-yl]-2, 5 diphenyl tetrazolium bromide) assay. The crystallization of the materials was increased by sintering temperature. Heat treatment did not inhibit the bioactive behavior of the materials as apatite formation started after 3 days in SBF. C2, C3 showed some indications of apatite forming even from the first day. Regarding cell viability, a variety of biological behaviors, concerning both dose and time points, was observed between the positive control and the tested materials by both the MTT assay and oxidative stress analysis. In conclusion, the nanobioceramic materials of this study possess a multitude of attractive physicochemical and biological properties that make them suitable candidates for bone regeneration applications, fillers in nanocomposite scaffolds, or as grafts in bone cavities and periodontal lesions.

Highlights

Bioactive ceramics and glass-ceramics are a unique group of synthetic materials that react with biological fluids, presenting enhanced capability of biointegration [1,2,3,4,5,6]
Concerning C1, except for the calcium siliceous phases, the Mg incorporation into the silicate lattice was confirmed by the X-ray diffractometry (XRD) peaks in those areas where broad but characteristic peaks appeared
Some of the identified phases were not verified from the Fourier transform infrared spectroscopy (FTIR) analysis, as the synthesized materials consisted mainly of calcium-silicate compounds, which presented a high overlapping in the MIR area

Summary

Introduction

Bioactive ceramics and glass-ceramics are a unique group of synthetic materials that react with biological fluids, presenting enhanced capability of biointegration [1,2,3,4,5,6] Numerous studies, both in vitro and in vivo, have demonstrated the ability of these materials to bond with living tissues, especially bone, through the development of a surface apatite layer [7,8,9,10,11,12,13]. Different types of silica-based nanomaterials, such as fumed silica, non-porous silica, and porous silica materials, have different cytotoxicity responses, with the last ones exhibiting the lowest values in a broad range of cell types [31,32,33,34,35,36,37,38]

Objectives

Methods

Results

Discussion

Conclusion