Heterogeneous growth of palladium nanocrystals on upconversion nanoparticles for multimodal imaging and photothermal therapy

Abstract

Nanocomposites have been playing an increasingly significant role in the bioimaging-guided visualization of cancer physiotherapy. However, it has been a challenge to explore new diagnosis and treatment reagents with small size, good stability, and high photothermal conversion efficiency. Herein, we report a novel preparation of nanocomposites based on the heterogeneous growth of nano-palladium on the surface of upconversion nanoparticles (UCNPs). The final poly vinylpyrrolidone (PVP) modified UCNPs@Pd nanocomposites possess a small size and exhibit good monodispersity, biocompatibility and high photothermal conversion efficiency. In addition, relevant cellular assays show that based on the growth of palladium, the UCNPs@Pd-PVP nanocomposites can effectively kill HeLa cells under 808 nm laser irradiation. The nanocomposites also present effective upconversion luminescence imaging and T₁ signal enhancement capability based on Er³⁺ and Gd³⁺ ions, respectively. Therefore, the nanocomposites successfully integrate upconversion luminescence imaging, magnetic resonance imaging, and photothermal therapy. This work provides new insights for the future development of multi-application materials based on the multicomponent heterogeneous growth of nanocomposites.