A new strategy to directly construct hybrid luminescence–photothermal–magnetism multifunctional nanocomposites for cancer up-conversion imaging and photothermal therapy

Abstract

Hybrid multifunctional nanocomposites with low toxicity have attracted considerable research attention in biomedical fields. Here, we report the development of the hybrid multifunctional Ag/NaGdF₄:Yb³⁺,Er³⁺ nanocomposites possessing of luminescence, photothermal and magnetism properties. The structure, morphology, composition and properties of the hybrid nanocomposites were confirmed by X-ray power diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectrometery (EDS), UV-Vis absorption (UV-Vis), Fourier transform-infrared (FT-IR) spectroscopy, up-conversion luminescence spectroscopy, sensitive thermometry, vibrating sample magnetometry (VSM) and cytotoxicity assay. The results show that the NaGdF₄:Yb³⁺,Er³⁺ nanoparticles are coated on the surface of Ag nanospheres. The nanocomposites exhibit bright green up-conversion luminescence under irradiation with a 980 nm laser and magnetism properties with a room-temperature magnetization value of 1.5669 emu g⁻¹ at 20 kOe. In addition, we examined the temperature changes when the solutions of samples were exposed to a 980 nm NIR laser. In vitro cell cytotoxicity assays on U87MG cancer cells demonstrate that the nanocomposites exhibit low toxicity and good biocompatibility. Furthermore, the up-conversion luminescence imaging and the photothermal therapy of Ag/NaGdF₄:Yb³⁺,Er³⁺ nanocomposites were realized under 980 nm NIR laser excitation, confirming that the nanocomposites are potential candidates as bioimaging and photothermal agents. Taken together, these results indicate that the prepared hybrid Ag/NaGdF₄:Yb³⁺,Er³⁺ multifunctional nanocomposites with luminescence–photothermal–magnetism properties have great promise in future bioimaging and targeted therapy of tumors.