Executive Summary : | Persistent luminescent materials emit light in the visible range for hours after radiation exposure, due to defects in the forbidden gap. These materials are increasingly being used in medical diagnostics, night vision, and temperature sensors. Red or near-infrared emission materials are emerging as probes for in vivo small animal optical imaging, where the emission must be located in the biological optical window between 600 nm and 1100 nm. Red persistent luminescence offers numerous advantages over conventional fluorescence techniques, but in vivo fluorescence imaging is not possible due to the absorption of UV or visible light by tissues. A new candidate for near-infrared persistent luminescent bio-markers has been unveiled with ZnGa2O4:Cr3+ (ZGO:Cr), which presents enhanced optical properties. This development has led to the description of a persistent luminescence-based Förster resonance energy transfer and the first proofs that these nanocrystals could be directed against malignant cells through proper surface functionalization with targeting ligands. Controlling the electron trap depth to enhance optical properties is crucial for in vivo application. However, nanoparticles for bio-imaging application still pose challenges, and their bio-distribution is highly dependent on core diameter and global surface charge. The intensity of luminescence from nanoparticles reported so far is not very intense, revealing the need for new nanomaterials. Photostimulable storage materials exhibiting photostimulated luminescence (PSL) will be prepared for possible application as biomarkers. |