Red and near infrared persistent luminescence nano-probes for bioimaging and targeting applications

The introductory aspect of this review starts with a prologue on bioimaging in general and optical imaging in particular, and finally focuses on the most recently explored red and near infrared (NIR) emitting persistent luminescence nanoparticles (PLNPs) for bioimaging applications. Accordingly, a pre-requisite towards a better understanding of the subject makes it vital to talk about persistent luminescence, and the developments in red and NIR emitting persistent phosphors. In this context, different synthesis techniques to design nanoparticles and chemically modified (surface modification) nanostructures have also been summarized. Finally, the use of these nanostructures as bioimaging and targeting probes, both for in vitro and in vivo studies, in diverse frameworks, has been reviewed in detail. The significant findings suggest that, Mn2+ and/ or Cr3+ doped nanostructures, particularly gallogermanates, are able to give an intense red-near infrared persistent emission with a longer afterglow time for more than 2 weeks and are suitable for bio-imaging applications. The review also talks about the remaining challenges, new dimensions and future course of research in this field.