Pore-engineered Ca2SiO4:Eu3+ nanophosphors with enhanced photoluminescence and biocompatibility for bioimaging applications

The development of efficient red-emitting nanomaterials is critical for next-generation applications in bioimaging, drug delivery, and photonics. Calcium silicate nanophosphors doped with europium ions (Eu 3+ ) are promising due to their biocompatibility and tunable optical properties. In this study, Eu 3+ -doped calcium silicate (Ca 2 SiO 4 :Eu 3+ ) nanoparticles were synthesized using dendritic mesoporous silica nanoparticles (DMSNs) as structural templates. By modulating the pore architecture via ammonium nitrate etching, a series of nanostructures (C 2 S 1 -C 2 S 5 ) with varying morphologies and porosities was obtained. Structural characterization confirmed the successful replication of the dendritic framework and uniform Eu 3+ incorporation, particularly in C 2 S 5 . Photoluminescence analysis revealed intense red emission, with C 2 S 5 exhibiting the highest quantum yield (81%) under 393 nm excitation. The enhanced luminescence was attributed to increased pore complexity and local structural asymmetry. Biodegradability studies in simulated body fluid showed controlled degradation, while in vitro assays confirmed efficient cellular uptake and high cytocompatibility (cell viability >75%). These results position C 2 S 5 as a promising multifunctional nanoplatform with high luminescence efficiency, structural tunability, and excellent bioresponse, suitable for theranostic and optical applications.