A highly efficient multifunctional nanoplatform for simultaneous upconversion luminescence (UCL) imaging and photodynamic therapy has been developed on the basis of selective energy transfer from multicolor luminescent NaYF(4):Yb(3+),Er(3+) upconversion nanoparticles (UCNPs) to photosensitizers (PS). Different from popular approaches based on electrostatic or hydrophobic interactions, over 100 photosensitizing molecules were covalently bonded to every 20 nm UCNP, which significantly strengthened the UCNP-PS linkage and reduced the probability of leakage/desorption of the PS. Over 80% UCL was transferred to PS, and the singlet oxygen production was readily detected by its feature emission at 1270 nm. Tests performed on JAR choriocarcinoma and NIH 3T3 fibroblast cells verified the efficient endocytosis and photodynamic effect of the nanoplatform with 980 nm irradiation specific to JAR cancer cells. Our work highlights the promise of using UCNPs for potential image-guided cancer photodynamic therapy.
Recent efforts and progress in unraveling the fundamental mechanism of excitation energy migration dynamics in upconversion nanomaterials are covered in this review, including short-and long-term interactions and other interactions in homogeneous and heterogeneous nanostructures. Comprehension of the role of spatial confinement in excitation energy migration processes is updated. Problems and challenges are also addressed.
Key learning points(1) Energy migration dynamics and interactions in upconversion nanosystems.(2) Excitation energy loss channels in upconversion nanomaterials. (3) Challenges in acquiring a high efficiency and broad excitation spectrum of upconversion emission in nanomaterials.
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