Fig. 2

a Schematic illustration of nanoprobe H-MnO₂/DOX/BPQDs synthesis route and its applications for hypoxic cancer multimodal imaging and synergistic therapy, involving MR/FL imaging and enhanced PDT/PTT/chemotherapy. b TEM photos of H-MnO₂/DOX/BPQDs incubated with pH 7.4 (physiological condition) and pH 5.5 buffer (tumor environment) for different times. c Percentages of released DOX from H-MnO₂/DOX/BPQDs over time in the PBS at different pH values (7.4, 6.5, and 5.5). Data were presented as means ± standard deviation (s.d.) (n = 3). d The ¹O₂ generation ability of H-MnO₂/DOX/BPQDs in air with 1,3-diphenylisobenzofuran (DPBF). e Photothermal heating curves of the H-MnO₂/DOX/BPQDs aqueous dispersions with different concentrations (0, 0.1, and 0.2 mg mL^− 1) and H-MnO₂/DOX upon 808 nm laser irradiation (1.0 W cm^− 2). f The dissolved O₂ concentration in 100 μm H₂O₂ solutions after treated with different concentrations of H-MnO₂/DOX/BPQDs (0, 0.1, and 0.2 mg mL^− 1). g Confocal images of intracellular ROS generation in HepG2 cells treated with Control + L630 (I), H-MnO₂/DOX + L630 (II), BPQDs-PEG-NH₂ + L630 (III), and H-MnO₂/DOX/BPQDs + L630 (IV), as detected with 2′,7′-dichlorodihydrofluorescein diacetate (DCFH-DA). h Cell viability of HepG2 cells after treatment with various concentrations of H-MnO₂/DOX/BPQDs under 630 and/or 808 nm laser irradiation. i The photographs of tumor dissection of different treatment groups obtained at 15 days. j In vivo fluorescence images of HepG2 tumor-bearing mice at different time points after systemic administration of nanoprobe H-MnO₂/DOX/BPQDs (MnO₂: 10 mg kg^− 1; DOX: 4.5 mg kg^− 1; BPQDs: 10 mg kg^− 1) via tail vein injection. k In vivo T₁-MR images of a mouse taken before and after systemic administration of H-MnO₂/DOX/BPQDs at 24 h. Reproduced with permission from Ref. [93]. Copyright 2021, Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim