Ti₃C₂ MXene Nanosheets Functionalized with NaErF₄:0.5%Tm@NaLuF₄ Nanoparticles for Dual-Modal Near-Infrared IIb/Magnetic Resonance Imaging-Guided Tumor Hyperthermia

Although the advent of two-dimensional (2D) MXenes has substantially increased the family of 2D materials and diverse applications, the rational design of MXene-based composites and their specialized applications in theranostic biomedicine remain a challenge. In this work, we developed, for the first time, Ti3C2 MXene nanosheets for near-infrared (NIR)-IIb (1530 nm) and magnetic resonance (MR) imaging-guided photothermal therapy. Surface engineering and functionalization of 2D Ti3C2 MXene nanosheets with NaErF4:0.5%Tm@NaLuF4 (NaErF4) nanoparticles result in NaErF4@Ti3C2 composites that emit in the NIR-IIb region at 1530 nm under 808 nm excitation, conferring NIR-IIb imaging guidance and monitoring capabilities during tumor hyperthermia. Due to the inherent magnetic properties of the Er3+ ions, the NaErF4@Ti3C2 composite can also be used for efficient T2-weighted MR imaging. In particular, based on the high photothermal conversion capability (43.62% at 808 nm irradiation) and photothermal stability, the designed composites were further explored for efficient tumor ablation with an inhibition ratio of 92.9%, which was systematically demonstrated both in vitro and in vivo. No significant nanocomposite toxicity was observed at the injected dose. This work not only expands the performance of MXene-based multifunctional nanostructures but also highlights the promise of their versatile applications in cancer therapy.