27. in vitro evaluation of luminescent rare-earth doped hydroxyapatite scaffolds

Department: Mechanical & Aerospace Engineering
Research Institute Affiliation: Agile - CaliBaja Center for Resilient Materials & Systems
Faculty Advisor(s): Olivia A. Graeve

Primary Student
Name: Fabian Martin Martinez Pallares
Email: fmm003@ucsd.edu
Phone: 858-534-5698
Grad Year: 2018

Abstract
We present a cathodoluminescence study of the chemical decomposition of rare-earth doped hydroxyapatite scaffolds in the presence of synthetic body fluids. One strategy to repair or replace bone is to engineer bone tissue through a combination of scaffolds, implanted cells, and biologically active molecules. An ideal bone scaffold should be biocompatible and biodegradable. Hydroxyapatite (HAp) materials are widely applied as biomedical materials, because of their excellent biocompatibility, osteoinductive properties, and similarity to the inorganic component of human bones. However, the measurement of the stability of HAp scaffolds demonstrates a partial deterioration with time. Rare-earth elements (RE) are used for labeling due to their well known luminescent properties. In this study, rare-earth doped hydroxyapatite (HAp:RE) was synthesized by the solution combustion synthesis method. The resultant scaffolds were obtained by mixing gelatin with the HAp:RE powders (HAp:Eu, HAp:Ce, HAp:Tb and HAp:Yb), and shaped using a syringe as an extruder. The manufactured scaffolds were analyzed by X-ray diffraction, catodoluminescence (CL) technique, and energy dispersive spectroscopy (EDS). In order to mimic the behavior of the scaffolds in the human body, the scaffolds were soaked in a simulated body fluid and phosphate buffer solution for four weeks. One piece from the structure of the scaffold was taken each week. The chemical stability of the scaffolds and were evaluated by measuring their CL properties. After each week, a decrement in the emission intensity was found for all the materials, due to the chemical reactions produced on the surface of the scaffolds. Based on the intensity of emission of the materials at different times, Eu was found to be the most stable dopant for HAp. The lifetime of the scaffolds was determined indirectly using HAp:RE scaffolds with known concentrations of RE elements. The results of this work might be utilized to develop HAp:RE scaffolds for slowly dissolving synthetic HAp in bone tissue, as well as for producing sensors to detect medical implant functionality

Industry Application Area(s)
Life Sciences/Medical Devices & Instruments | Materials

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