Development of Biophotonic Scaffolds for Infection Eradication

Abstract

This thesis investigates the development of biophotonic scaffolds with near-infrared (NIR) rechargeable luminescence for potential biomedical applications, particularly light-triggered antimicrobial therapy and tissue regeneration. The study addresses the challenge of integrating persistent luminescence (PeL) and upconversion (UC) functionalities into bioactive glass scaffolds while preserving their mechanical integrity and optical performance.

Rare-earth-doped UC crystals, including CaTeO3 and NaNbO3, were synthesized via solid-state reactions and optimized for blue emission under 808 nm and 980 nm excitation. These emissions served to charge SrAl2O4: Eu²⁺, Dy³⁺ phosphors, which provide long-lasting green afterglow. Structural characterization using X-ray diffraction confirmed successful incorporation of dopants, while optical analyses revealed stronger blue emission in NaNbO3, especially when doped with 15 at% Yb3+ and 0.25 at% Tm, compared to CaTeO3.

Composite inks were formulated by combining optimized UC crystals, PeL phosphors, and 1393B20 borosilicate bioactive glass. Although nozzle clogging limited successful 3D printing, sintered ink samples displayed visible green afterglow following NIR excitation, confirming that UC emission effectively recharged PeL phosphors. However, the trade-off between luminescent performance and mechanical stability was evident, as NaNbO₃-based composites exhibited higher emission but increased brittleness.

The results demonstrate the feasibility of producing multifunctional photonic scaffolds capable of localized light-activated functionality, while highlighting key areas for optimization, including particle size control, ink rheology, and sintering protocols. These findings provide a foundation for future studies focused on enhancing luminescent efficiency, mechanical robustness, and biological performance for clinical translation in regenerative medicine.