Luminescence based temperature bio-imaging: Status, challenges, and perspectives

The only way to get thermal images of living organisms without perturbing them is to use luminescent probes with temperature-dependent spectral properties. The acquisition of such thermal images becomes essential to distinguish various states of cells, to monitor thermogenesis, to study cellular activity, and to control hyperthermia therapy. Current efforts are focused on the development and optimization of luminescent reporters such as small molecules, proteins, quantum dots, and lanthanide-doped nanoparticles. However, much less attention is devoted to the methods and technologies that are required to image temperature distribution at both in vitro or in vivo levels. Indeed, rare examples can be found in the scientific literature showing technologies and materials capable of providing reliable 2D thermal images of living organisms. In this review article, examples of 2D luminescence thermometry are presented alongside new possibilities and directions that should be followed to achieve the required level of simplicity and reliability that ensure their future implementation at the clinical level. This review will inspire specialists in chemistry, physics, biology, medicine, and engineering to collaborate with materials scientists to jointly develop novel more accurate temperature probes and enable mapping of temperature with simplified technical means.