Study of Ln³⁺ (Nd³⁺, Yb³⁺, and Er³⁺) doped GAG matrices exhibiting upconversion luminescence for biomedical applications

This study investigates the synthesis and luminescent properties of Nd³⁺, Yb³⁺, and Er³⁺-doped gadolinium aluminum garnet (GAG) prepared by the non-hydrolytic sol-gel method. The influence of lanthanide co-doping on energy transfer and optical performance was evaluated through structural, morphological, and spectroscopic characterization. Selected samples were further coated with silica to obtain core-shell structures with improved biocompatibility. The developed materials are promising for near-infrared luminescence, particularly within the biological optical window, making them attractive for future biomedical applications such as bioimaging and optical sensing.