Investigating the Structure, Solubility and Bioactivity of Na/Sr Bioactive Glasses/Glass-Ceramics
Date
2014-09
Authors
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Publisher
New York State College of Ceramics at Alfred University. Kazuo Inamori School of Engineering.
Abstract
This project was to investigate the structure, solubility and bioactivity of Na/Sr Bioactive
glasses. There are three sections to this study. The first section is the effect of Na+ and Sr2+ on the
structure and biocompatibility of the glasses. Three glasses (Ly-N, Ly-C, Ly-S) were formulated
with the substitution of sodium (Na+) and strontium (Sr2+) within the glass. X-ray diffraction
(XRD), X-ray Fluorescence (XRF), Differential Thermal Analysis (DTA), Hot Stage Microscope
(HSM) were used to characterize the series of glasses. Results of Network Connectivity (NC), Xray
Photoelectron Spectroscopy (XPS), Raman Spectroscopy, Magic Angle Spinning – Nuclear
Magnetic Resonance (MAS-NMR) presented that the three glasses have very similar structure and
Na+ and Sr2+ both act as network modifiers. Cell Culture testing was conducted to investigate the
biocompatibility and bioactivity of these glasses. The series of glasses have no negative influence
on the cell viability, and addition of Sr2+ increase the cell viability. The second section investigates
the mechanical durability of the bioactive glasses as a function of structure, solubility and
incubation time. Samples were sintered to amorphous and crystalline structures. Ion release
profiles were determined over 1, 7 and 30 days and in each case ion release was greatly reduced
when the materials were crystallized. pH changes were reduced with the onset of crystallization
compared to the amorphous counterparts. The highest concentrations of Na+ (216 μg/mL) and Si4+
(172 μg/mL) both coming from Ly-N with amorphous structure. Crystalline samples presented
much higher hardness values which did not reduce with respect to incubation time. However, the
hardness of amorphous samples was found to experience significant reduction. The third part is
simulated body fluid (SBF) testing and cytocompatibility of the glasses. In this section, sintered
glass powder discs (amorphous /crystalline) were used to do SBF trials. Each material was
subjected to maturation in SBF after 1, 7 and 30 days to describe any change in surface
morphology. Scanning Electron microscopy (SEM) was used to observe the calcium phosphate
(CaP) layers formed on the surface of each material. CaP deposition was observed predominantly
on Na+-containing amorphous and crystalline materials. Limited CaP deposition was observed on
the surface of Sr2+-containing crystalline materials. Cell culture analysis presented an increase in
cell viability with Na+-containing materials and a general reduction in cell viability with Sr2+-
containing material, however these reduction were not significant.
Description
Advisory committee members: Nathan Mellott, Alexis Clare. Dissertation completed in partial fulfillment of the requirements for the degree of Masters of Science in Biomaterials Engineering at the Kazuo Inamori School of Engineering, New York State College of Ceramics at Alfred University
Type
Thesis