A Local Water Molecular-Heating Strategy for NIR Long-Lifetime Imaging-Guided Photothermal Therapy of Deep-Tissue-Bearing Tumor

1.0 μm near-infrared (NIR) is considered unsuitable as an imaging and analytical signal in biological environments owing to the strong absorption of water at around the regions. However, the 1.0 μm NIR can be converted to heat and used as a local water-molecular heating strategy for photothermal therapy of biological tissues. Herein, we designed a we developed Nd-sensitized 1.0 μm emissive core@shell NPs (NaYF₄:50%Yb@NaYF₄:40%Nd,20%Yb, denoted as water-heating NPs) as a local water-molecular heating material as a strong 1.0 μm emissive NP to target the absorption band of water. Especially, the strong energy absorption coefficient derived from the overtones and the stretching vibrations of O–H oscillators matches the emission spectrum of water-heating NPs. Furthermore, introducing Tm ions into the water-heating NPs enabled the NIR lifetime, and it was developed as an NIR imaging-guided water-heating probe (water-heating NIR NPs). In the glioblastoma multiforme (GBM) mouse model, tumor-targeted water-heating NIR NPs reduced the tumor volume by 78.9% in the presence of high-resolution intracranial NIR long-lifetime imaging. Hence, water-heating NIR NPs can be used as a novel nanomaterial for imaging and photothermal ablation in deep-tissue-bearing tumor therapy.