Smart photopharmacological agents: LaVO4:Eu3+@vinyl phosphonate combining luminescence imaging and photoswitchable butyrylcholinesterase inhibition

Abstract

The combination of photoswitchability and bioactivity in one compound provides interesting opportunities for photopharmacology. Here, we report a hybrid compound that in addition allows for its visual localization. It is the first demonstration of its kind and it even shows high photoswitchability. The multifunctional nanomaterial hybrid, which we present, is composed of luminescent LaVO₄:Eu³⁺ nanoparticles and vinyl phosphonate, the latter of which inhibits butyrylcholinesterase (BChE). This inhibition increases 7 times when irradiated with a 266 nm laser. We found that it is increased even further when vinyl phosphonate molecules are conjugated with LaVO₄:Eu³⁺ nanoparticles, leading in total to a 20-fold increase in BChE inhibition upon laser irradiation. The specific luminescence spectrum of LaVO₄:Eu³⁺ allows its spatial localization in various biological samples (chicken breast, Daphnia and Paramecium). Furthermore, laser irradiation of the LaVO₄:Eu³⁺@vinyl phosphonate hybrid leads to a drop in luminescence intensity and in lifetime of the Eu³⁺ ion that can implicitly indicate photoswitching of vinyl phosphonate in the bioactive state. Thus, combining enhanced photoswitchability, bioactivity and luminescence induced localizability in a unique way, hybrid LaVO₄:Eu³⁺@vinyl phosphonate can be considered as a promising tool for photopharmacology.