Persistent luminescence of AB2O4:Cr3+ (A = Zn, Mg, B = Ga, Al) spinels: New biomarkers for in vivo imaging

• Persistent luminescent materials emit light during long time after the stop of their exposure to radiation.
• Chromium doped AB2O4 spinels are suitable for in vivo optical imaging.
• Traps could be emptied by thermal or near infrared source.

Recently red emitting long-lasting phosphorescence (LLP) materials have been demonstrated to be useful biomarkers for small animal in vivo imaging. We report here our investigations on the optical properties of chromium doped AB2O4 spinels (with A = Zn, Mg and B = Ga, Al) suitable for such applications. It is possible to tune the absorption wavelengths of Cr3+ by a crystal field variation and also slightly vary the emission to be better centered in the biological window and to adjust the trap depth in order to better control the release of the charges. These traps are therefore stable at room temperature and could be emptied by thermal or near infrared source, which makes these materials potential new optically photo-storage compounds.