Black TiO₂-based nanoprobes for: T ₁-weighted MRI-guided photothermal therapy in CD133 high expressed pancreatic cancer stem-like cells

At present, transmembrane glycoprotein CD133 highly expressed pancreatic cancer stem cells (PCSCs), with the features of chemotherapeutic/radiotherapeutic resistance and exclusive tumorigenic potential, are considered as the primary cause of metastasis and recurrence in pancreatic cancer, and therefore are an effective target in the disease treatment. Furthermore, with the launch of precision medicine, multifunctional nanoprobes have been applied as an efficient strategy for the magnetic resonance imaging (MRI)-guided photothermal therapy (PTT) of pancreatic cancer. In this research, with the aim of achieving precise MRI-guided PTT in CD133 highly expressed PCSCs, novel bTiO₂-Gd-CD133mAb nanoprobes were designed and successfully prepared by loading Gd-DOTA and CD133 monoclonal antibodies on black TiO₂ nanoparticles. It was very interesting to find that the r₁ relaxivity value of the nanoprobes was 34.394 mM^-1 s^-1, about 7.5 times that of commercial Magnevist (4.5624 mM^-1 s^-1), which indicates that the nanoprobes have good potential as MRI T₁ contrast agents with excellent performance. Herein, CD133 highly expressed PANC-1 cells were selected and verified as PCSCs model. In vitro experiments demonstrated that the nanoprobes exhibited active-targeting ability in PANC-1 cells, and consequently could specially enhance T₁-weighted MR imaging and 808 nm near-infrared (NIR)-triggered PTT efficiency in the PCSCs model. Our study not only provides a new strategy for the effective treatment of pancreatic cancer and its' stem cells, but also further broadens the application of black TiO₂ in the field of cancer theranostics.