One-step solvothermal synthesis of targetable optomagnetic upconversion nanoparticles for in vivo bimodal imaging

Bionanoparticles and nanostructures with high biocompatibility and stability, low toxicity, diversification of imaging modality, and specificity of targeting to desired organs or cells are of great interest in nanobiology and medicine. However, integrating all of these desired features into a single bionanoparticle, which can be applied to biomedical applications and eventually in clinical prediagnosis and therapy, is still a challenge. We herein report a facile one-step solvothermal approach to fabricate targetable and biocompatible β-NaYF4:Yb,Gd,Tm upconversion nanoparticles (UCNPs) with bimodal-signals (near-infrared (NIR) fluorescence and magnetic resonance (MR) signals) using hyaluronic acid (HA) as a multifunctional molecule. The prepared UCNPs with low toxicity are successfully applied for in vitro and in vivo targeted tumor imaging. The developed biomimetic surface modification approach for the synthesis of biomolecule-guided multifunctional UCNPs holds great potential applications in medical diagnostics and therapy.