in vitro evaluation of luminescent rare-earth doped hydroxyapatite scaffolds

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

Primary Student
Name: Fabian Martin Martinez Pallares
Phone: 858-214-9794
Grad Year: 2019

In this work, we present a study of the proliferation of murine preosteoblasts on tri-calcium phosphate/hydroxyapatite scaffolds doped with rare earth and its biocompatibility study through a hemolysis assay. One strategy to repair or replace bone is by designing bone tissues through a combination of scaffolds, implanted cells and biologically active molecules. The main characteristics that a scaffold must have to be used in bone tissues are biocompatibility and biodegradability. Hydroxyapatite (HAp) is a compound that is widely used in biomedical materials, due to its excellent biocompatibility, osteoconductive properties and its similarity to the inorganic composition of human bones. However, the stability of the HAp scaffolds shows a partial deterioration due to its resorption in living tissue with respect to time. On the other hand, rare earth (RE) ions have been of great interest due to their use as markers for their luminescent properties and their use as biolabels. In this study, rare earth doped hydroxyapatite (HAp:RE) was synthesized by the combustion method. The tri-calcium phosphate/hydroxyapatite mixture was obtained by heat treatment of the HAp:RE (at 1000C for different periods of time). The scaffolds were constructed by mixing gelatin with TCP/HAp:RE (RE = Eu, Ce, Tb or Yb), and shaped using a syringe as an extruder. The fabricated scaffolds were analyzed by X-ray diffraction (XRD). The cell proliferation tests were carried out by means of a colorimetric test with resazurin, placing part of the scaffold in contact with pre-osteoblasts, the cell proliferation was analyzed after 24, 48, and 72 hours and compared with the number of pre-osteoblasts cultured in the absence of the scaffolds. The hemolytic assay was studied by placing a solution of erythrocytes in contact with the scaffolds. The XRD results show that the TCP/HAp ratio increases according to the thermal treatment time, the samples that were not thermally treated show a pure phase of HAp while the sample treated for the longest time (10 h) shows the highest amount of TCP. Cell proliferation was favored in those cells that were in contact with TCP/HAp:RE. All the materials presented a percentage of hemolysis less than 5%, which suggests that the scaffolds do not induce the destruction of erythrocytes. The results of this work could be used for the development of scaffolds that can be reabsorbed in a controlled manner in the bone tissue, as well as to produce sensors that help detect the functionality of medical implant.

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

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