The explosion of emerging high-performance 2D MXenes in theranostic nanomedicine is still at the preliminary stage. Despite tremendous efforts devoted to photonic tumor hyperthermia, current photothermal-conversion nanoagents still suffer from critical issues preventing further clinical translation such as low biodegradability. Here, for the first time, the construction of novel 2D molybdenum carbide (Mo 2 C) MXenes for photonic tumor hyperthermia is reported. The structure of both bulk Mo 2 Ga 2 C ceramic and Mo 2 C MXene is fully revealed. Especially, computational simulation, as a novel strategy and a powerful tool for photonic-performance prediction, is employed to reveal that Mo 2 C MXene is featured with intense near-infrared (NIR) absorption, covering the first and the second biological transparency window (NIR I and II). After further surface engineering with polyvinyl alcohol (PVA), Mo 2 C-PVA nanoflakes exhibit high biocompatibility and fast degradability. Importantly, it is experimentally corroborated that Mo 2 C-PVA nanoflakes possess intriguing broad absorption band spanning NIR in both the I and II regions, and desirable photothermal-conversion efficiency (24.5% for NIR I and 43.3% for NIR II). This study not only broadens the nanomedical applications of MXene by fabricating novel material members (Mo 2 C), but also provides the paradigm of inorganic multifunctional biomedical nanoplatform with desirable biodegradability and high therapeutic performance.

Photonic cancer hyperthermia has been considered to be one of the most representative noninvasive cancer treatments with high therapeutic efficiency and biosafety. However, it still remains a crucial challenge to develop efficient photothermal nanoagents with satisfactory photothermal performance and biocompatibility, among which two-dimensional (2D) ultrathin nanosheets have recently been regarded as the promising multifunctional theranostic agents for photothermal tumor ablation. In this work, we report, for the first time, on the construction of a novel kind of photothermal agents based on the intriguing 2D antimony(III) selenide (Sb 2 Se 3 ) nanosheets for highly efficient photoacoustic imaging-guided photonic cancer hyperthermia by nearinfrared (NIR) laser activation. These Sb 2 Se 3 nanosheets were easily fabricated by a novel but efficiently combined liquid nitrogen pretreatment and freezing−thawing approach, which were featured with high photothermal-conversion capability (extinction coefficient: 33.2 L g −1 cm −1 ; photothermal-conversion efficiency: 30.78%). The further surface engineering of these Sb 2 Se 3 ultrathin nanosheets with poly(vinyl pyrrolidone) (PVP) substantially improved the biocompatibility of the nanosheets and their stability in physiological environments, guaranteeing the feasibility in photonic antitumor applications. Importantly, 2D Sb 2 Se 3 −PVP nanosheets have been certificated to efficiently eradicate the tumors by NIR-triggered photonic tumor hyperthermia. Especially, the biosafety in vitro and in vivo of these Sb 2 Se 3 ultrathin nanosheets has been evaluated and demonstrated. This work meaningfully expands the biomedical applications of 2D bionanoplatforms with a planar topology through probing into new members (Sb 2 Se 3 in this work) of 2D biomaterials with unique intrinsic physiochemical property and biological effect.