Recent advances in chromophore-assembled upconversion nanoprobes for chemo/biosensing

Lanthanide-doped upconversion nanoparticles (UCNPs) have recently aroused enormous attention, due to large anti-Stokes shifts, weak autofluorescence, less photodamage and photobleaching, as well as deeper tissue penetration. Owing to their advantageous photophysical properties, UCNPs have been widely applied in analytical and biomedical research fields, such as sensing, imaging, and therapy. This review mainly focuses on recent advances in chromophore-assembled upconversion nanoprobes (UC nanoprobes) for chemo/biosensing. We first demonstrate the principle for constructing UC nanoprobes, and then give a detailed summary of chromophore loading strategies. Furthermore, recent achievements on the construction and application of chromophore-loaded UC nanoprobes are summarized. Also, the current challenges and future prospects of UC nanoprobes are discussed as a conclusion. We expect this review will offer valuable guidance on the selection of chromophores and their loading strategies to further facilitate the fabrication and applications of chromophore-assembled UC nanoprobes.