UC San Diego

This dissertation explores the multifaceted roles of rare-earth doped hydroxyapatite in biomedical applications, bridging the gap between luminescence studies and osteogenic potential in the context of bone tissue engineering and regenerative medicine. In the second chapter, we look into the luminescence properties of terbium, cerium, and europium doped hydroxyapatite scaffolds when immersed in simulated body fluid (SBF) over a four-week period. Our comprehensive study reveals a consistent decrease in luminescence emission intensity across all samples, accompanied by a reduction in the concentration of rare-earth ions within the scaffolds, as confirmed by energy dispersive spectroscopy. Furthermore, fluorescence spectroscopy demonstrates the translocation of these ions into the SBF, indicating the scaffolds' partial dissolution over time. The employment of rare-earth ions as luminescence markers offers profound insights into apatite formation mechanisms, presenting significant implications for the development of safer and more durable materials in biomedical applications.Expanding upon the foundational knowledge established in the first and second chapters, the third chapter investigates the osteogenic potential of rare-earth doped hydroxyapatite scaffolds using a murine pre-osteoblastic cell line. This study assesses the effects of ytterbium, terbium, cerium, and europium doping on osteoblast differentiation, gauged by alkaline phosphatase activity and the expression of osteogenic marker genes such as Runx2, OCN, ALP, OPN, and BMP2. Our findings indicate a notable enhancement in differentiation activity with the incorporation of rare-earth elements, with europium and ytterbium doped HAp showing superior performance. Cathodoluminescence spectroscopy further corroborates these results by revealing distinct emission peaks specific to the Eu2+/Eu3+ and Yb2+ ions, underscoring the role of valence state incorporation in augmenting osteoblast differentiation. Collectively, this dissertation contributes expanding the field of biomaterials by elucidating the dual utility of rare-earth doped hydroxyapatite scaffolds in promoting osteogenic differentiation and providing luminescence-based insights into scaffold behavior in physiological environments. By combining the luminescence stability studies with the exploration of osteogenic potential, our research underscores the importance of integrating multifunctional elements into scaffold design to enhance their performance in bone tissue engineering. The insights garnered from both studies not only pave the way for the development of novel biomaterials but also highlight the potential of rare-earth elements as pivotal components in the advancement of regenerative medicine and biomedical engineering.