Temperature-feedback two-photon-responsive metal-organic frameworks for efficient photothermal therapy

1.  Schematic illustration showing the preparation of AMPP, highlighting the process of temperature-sensitive photothermal therapy and promoted chemodynamic therapy.

Figure  1.  (a) SEM image of MOF-199. (b) TEM image of the Au NRs. (c) TEM image of AMPP. (d) TEM image and elemental mapping of AMPP. (e) Powder XRD patterns of simulated MOF-199, synthesized MOF-199 and AMPP. (f) BET results of MOF-199 and AMPP. (g) TGA curves of MOF-199 and AMPP. (h) UV‒vis absorption spectra of PyS, the Au NRs, MOF-199 and AMPP. Concentration: 100 μg·mL⁻¹; solvent: deionized water.

Figure  2.  (a) Illustration of the changes in the fluorescence intensity of PyS with temperature. (b) Two-photon excited fluorescence performance of PyS upon 900 nm laser excitation at different temperatures (concentration: 1 mmol·L⁻¹; solvent: PBS; temperature: 25 °C, 30 °C, 35 °C, 40 °C, 45 °C, 50 °C). (c) Two-photon excited fluorescence spectrum of AMPP (concentration: 150 μg·mL⁻¹; solvent: PBS; wavelength: 780–900 nm). (d) Two-photon excited fluorescence spectrum of AMPP upon 900 nm laser excitation with different input powers (concentration: 150 μg·mL⁻¹; solvent: PBS; power: 300–900 mW). (e) Two-photon excited fluorescence spectrum of AMPP upon 900 nm laser excitation at different temperatures (concentration: 150 μg·mL⁻¹; solvent: PBS; temperature: 25 °C, 30 °C, 35 °C, 40 °C, 45 °C, 50 °C). (f) The linear relationship between temperature and two-photon fluorescence intensity for AMPP.

Figure  3.  (a) The temperature variation of AMPP with different concentrations under NIR light (900 nm, 1.0 W·cm⁻²) for 10 min. (b) The temperature variation of AMPP with different input power densities under 900 nm (1.0 W·cm⁻²) laser irradiation for 10 min. (c) Photothermal conversion performance of AMPP (150 μg·mL⁻¹) obtained from linear time data vs. −In(θ) from the cooling period. (d) Infrared thermal images of MOF-199 (150 μg·mL⁻¹) and AMPP (150 μg·mL⁻¹) under 900 nm laser irradiation (1.0 W·cm⁻²). (e) Schematic illustration showing the temperature feedback and therapeutic process of AMPP.

Figure  4.  (a) Fluorescence intensity of AMPP within HepG2 cells under 513 nm and 900 nm laser irradiation. Right: the fluorescence intensity and corresponding temperature under different irradiation times. (b) CLSM images of HepG2 cells treated with AMPP (150 μg·mL⁻¹), and APF was used to detect the generation of •OH (AMPP: 150 μg·mL⁻¹; H₂O₂: 100 μmol·L⁻¹; scale bar: 25 μm). (c) CLSM images of AMPP-treated HepG2 cells stained with calcein-AM/PI (laser: 900 nm, 0.1 W·cm⁻²; AMPP: 150 μg·mL⁻¹; H₂O₂: 100 μmol·L⁻¹; scale bar: 100 μm). (d) AMPP-incubated HepG2 cells were stained with Annexin V-FITC/PI after irradiation (laser: 900 nm, 0.1 W·cm⁻²; AMPP: 150 μg·mL⁻¹; scale bar: 25 μm). (e) 3D fluorescence images of MCTs subjected to different treatments (laser: 900 nm, 0.1 W·cm⁻²; AMPP: 150 μg·mL⁻¹; H₂O₂: 100 μmol·L⁻¹).