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We present a luminescence study investigating the dissolution of rare-earth-doped hydroxyapatite scaffolds in simulated body fluid (SBF), aiming to assess the luminescence stability of Tb-, Ce-, and Eu-doped scaffolds over time. Our findings reveal a consistent decrease in luminescence emission intensity across all samples over a four-week period in which the scaffolds were immersed in the SBF. In addition, energy-dispersive spectroscopy confirms a decrease in rare-earth ion concentration in the scaffolds with respect to time, whereas fluorescence spectroscopy shows the presence of rare-earth ions in the SBF, indicating the partial dissolution of the scaffolds over time. The use of rare-earth ions as luminescence markers provides insights into the mechanisms of apatite formation in hydroxyapatites. Thus, these scaffolds may find wider use in regenerative medicine, particularly in targeted drug delivery systems, where their luminescent properties have the potential to noninvasively track drug release.
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Effect of simulated body fluid formulation on orthopedic device apatite‐forming ability assessment
Abstract Integration of native bone into orthopedic devices is a key factor in long‐term implant success. The material‐tissue interface is generally accepted to consist of a hydroxyapatite layer so bioactive materials that can spontaneously generate this hydroxyapatite layer after implantation may improve patient outcomes. Per the ISO 22317:2014 standard, “Implants for surgery – In vitro evaluation for apatite‐forming ability of implant materials,” bioactivity performance statements can be assessed by soaking the material in simulated body fluid (SBF) and evaluating the surface for the formation of a hydroxyapatite layer; however, variations in test methods may alter hydroxyapatite formation and result in false‐positive assessments. The goal of this study was to identify the effect of SBF formulation on bioactivity assessment. Bioglass® (45S5 and S53P4) and non‐bioactive Ti‐6Al‐4V were exposed to SBF formulations varying in calcium ion and phosphate concentrations as well as supporting ion concentrations. Scanning electron microscopy and X‐ray powder diffraction evaluation of the resulting hydroxyapatite layers revealed that SBF enriched with double or quadruple the calcium and phosphate ion concentrations increased hydroxyapatite crystal size and quantity compared to the standard formulation and can induce hydroxyapatite crystallization on surfaces traditionally considered non‐bioactive. Altering concentrations of other ions, for example, bicarbonate, changed hydroxyapatite induction time, quantity, and morphology. For studies evaluating the apatite‐forming ability of a material to support bioactivity performance statements, test method parameters must be adequately described and controlled. It is unclear if apatite formation after exposure to any of the SBF formulations is representative of an in vivo biological response. The ISO 23317 standard test method should be further developed to provide additional guidance on apatite characterization and interpretation of the results.
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- Award ID(s):
- 2037636
- PAR ID:
- 10400062
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Journal of Biomedical Materials Research Part B: Applied Biomaterials
- Volume:
- 111
- Issue:
- 5
- ISSN:
- 1552-4973
- Page Range / eLocation ID:
- p. 987-995
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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