Persistent luminescence and photochromism are two fascinating optical properties that involve charge trapping via defects and their release due to an external stimulation. In both processes, it is possible to define a "1" (or "on") and a "0" (or "off") optical state.Consequently, materials with one of these phenomena find major interest in view of designing smart, anticounterfeiting and optical information storage devices. Combining both processes within a single material can lead to a new generation of information storage phosphors, in which it may be possible to obtain three different optical states by playing on the external stimulations applied on the material. For that purpose, the elaboration of nickel-doped ZnGa 2 O 4 spinel transparent nano glass-ceramics is presented in this work. The short-wave infrared (SWIR) emission, a broad band located at ca. 1275 nm, arises from Ni 2+ cations located in gallium octahedral sites. SWIR persistent luminescence, arising from the same doping ion transition, can also be monitored after UV charging. Interestingly, UV irradiation

The use of luminescence in biological systems allows us to diagnose diseases and understand cellular processes. Persistent luminescent materials have emerged as an attractive system for application in luminescence imaging of biological systems; the afterglow emission grants background-free luminescence imaging, there is no need for continuous excitation to avoid tissue and cell damage due to the continuous light exposure, and they also circumvent the depth penetration issue caused by excitation in the UV-Vis. This review aims to provide a background in luminescence imaging of biological systems, persistent luminescence, and synthetic methods for obtaining persistent luminescent materials, and discuss selected examples of recent literature on the applications of persistent luminescent materials in luminescence imaging of biological systems and photodynamic therapy. Finally, the challenges and future directions, pointing to the development of compounds capable of executing multiple functions and light in regions where tissues and cells have low absorption, will be discussed.