Synthesis of rare earth nanoparticles and their use in in vivo biomedical applications

Abstract

Nanomaterials are an excellent alternative to conventional fluorescent probes (organic dyes and fluorescent proteins) because they overcome their main limitations. Thus, they increase resistance to photobleaching, photostability, enable multiplexing, extend lifetime, etc. Moreover, due to the versatility of nanomaterials and especially nanoparticles that can be modified on their surface, they increase biocompatibility in biological systems and specificity in targeting, which makes them an excellent option for in vivo and in vitro biomedical applications.Rare earth nanoparticles are of great interest for biomedical applications due to their unique physical and chemical properties. Ln3+ ions have highly degenerate electronic states and strongly favored f-f orbital transitions, which translate into specific optical properties such as large Stokes shifts, long lifetimes, sharp and intense emission bands, and considerable resistance to photobleaching and photochemical degradation. It is worth noting that in this type of nanoparticles, depending on the transitions that occur after the excitation process, light emission can occur through an upconversion process, in which multiple photons with lower energy produce emission with higher energy, or through a downshifting process. In this process, a photon with higher energy produces a lower emission. Thanks to this type of emission, rare earth nanoparticles can emit light in a wide range of the electromagnetic spectrum, from UV-vis emissions to near-infrared emissions, making them excellent fluorescent probes. Combining the above properties with the versatility these nanoparticles to bound biological molecules such as DNA, RNA proteins, etc., they are ideal candidates for theracnostic applications (detection and treatment) and are also suitable for bioimaging, as sensors and as drug carriers...