(a) 3D AFM image of Ti3C2 nanosheets. (b) Photothermal profile of Ti3C2 nanosheets in water. Adapted with permission from [81]. (b) at various concentrations of 0–100 μg/mL under irradiation (808 nm and 1.0 W/cm2) and (c) under different laser power densities of 0.3–1.5 W/cm2 at concentration of 50 μg/mL. (d) Photostability test performed in a solution containing Ti3C2 nanosheets under irradiation (808 nm, 1.5 W/cm2). (e) In vitro photothermal performance of Ti3C2, Ti3C2-DOX, and free DOX solutions under laser irradiation (808 nm, 1.0 W/cm2). Adapted with permission from [95]. (f) In vivo 2D B-mode ultrasound (US) imaging, PA imaging, and merged US and PA images of tumor after intravenous administration of Ti3C2-SP nanosheets at different time duration of 1–24 h. (g) The corresponding quantitative changes in PA signal intensity within the tumor have been shown. Adapted with permission from [28]. (h) Photographs of 4T1 tumor-bearing mice from the control group and PLGA/ Ti3C2 implant+NIR laser group on the 16th day of post-injection. (i) H&E, TUNEL, and Antigen Ki-67 immunofluorescence staining of tumor tissues of control and PLGA/Ti3C2 implant+NIR laser group after in vivo photothermal treatment (scale bar: 50 µm). Adapted with permission from [77].