Dendritic Mesoporous Silica Structuring of Eu³⁺-Doped Ca₂SiO₄ Nanophosphors for Bioimaging and Luminescent Applications

Rare-earth element-based nanophosphors are known for their exceptional optical properties, rendering them useful for applications in bioimaging and light-emitting diodes (LED). However, traditional phosphors often suffer from drawbacks such as photobleaching in organic dyes and toxicity of quantum dots. In this study, we address these challenges by employing dendritic mesoporous silica nanoparticles (DMSNs) as host materials for fabricating Eu3+-doped calcium silicate (Ca2SiO4) phosphors. The unique porous structure of DMSNs enables precise control of the Eu3+ concentration, resulting in enhanced crystallinity and optical performance. Eu3+-doped Ca2SiO4 nanophosphors are synthesized via a high-temperature hydrothermal process, and their structural, morphological, and optical properties are analyzed at various Eu3+ concentrations. Remarkably, the nanophosphors achieve a quantum yield of 69.7% with low amount of dopants (0.5 mol % Eu3+). The resulting nanophosphors, even fabricated with significantly reduced use of rare-earth elements compared to conventional phosphors, exhibit excellent structural stability, controlled particle sizes, and high fluorescence efficiency. Additionally, the nanophosphors showing excellent biodegradability and high cellular uptake in vitro experiments demonstrate their potential as cellular imaging probes. These results highlight the promise of Eu3+-doped Ca2SiO4 phosphors synthesized using DMSNs for applications in optical technologies, healthcare, and environmental solutions.