Synergistic effect of sunlight induced photothermal conversion and H2O2 release based on hybridized tungsten oxide gel for cancer inhibition

Abstract

A highly efficient photochromic hydrogel was successfully fabricated via casting precursor, which is based on amorphous tungsten oxide and poly (ethylene oxide)-block-poly (propylene oxide)-block-poly (ethylene oxide). Under simulated solar illumination, the hydrogel has a rapid and controlled temperature increasing ratio as its coloration degree. Localized electrons in the amorphous tungsten oxide play a vital role in absorption over a broad range of wavelengths from 400 nm to 1100 nm, encompassing the entire visible light and infrared regions in the solar spectrum. More importantly, the material exhibits sustainable released H₂O₂ induced by localized electrons, which has a synergistic effect with the rapid surface temperature increase. The amount of H₂O₂ released by each film can be tuned by the light irradiation, and the film coloration can indicate the degree of oxidative stress. The ability of the H₂O₂-releasing gels in vitro study was investigated to induce apoptosis in melanoma tumor cells and NIH 3T3 fibroblasts. The in vivo experimental results indicate that these gels have a greater healing effect than the control in the early stages of tumor formation.

Figure 1

The morphologies of (a) a-WO₃ and its XRD pattern in inserted figure, (b) fibers substrate in SEM images.

Figure 2

(a) Recorded transmittance of the casted hybrid nanocomposite before and after UV irradiation measured by UV-Vis spectroscopy, the scale bars of sample images are 2.7 cm; (b) IR thermal image of a 12-well plate containing samples, controls and blanks before and after 5 mins of irradiation; (c) Temperature increase dependence on irradiation time by AM 1.5 G, resistance analysis shown as inserted curve.

Figure 3. Electron spin resonance spectra of gel at 77 K under vacuum conditions after induction for 5 mins, 30 mins and 500 mins.

Figure 4

Accumulation of H₂O₂ concentration obtained over time and various temperature after UV irradiation for 30 secs under cold (a,b) and heat (c,d) surroundings, respectively. The original solution precursor was diluted into 2 and 8 times for fluorescence study.

Figure 5

(a) Facile casting of the precursor on the fiber substrate; (b) PDMS-packaged hybrid film; (c) tunable, controlled H₂O₂ release over the entire white light spectrum.

Figure 6. A375 cell behavior on PDMS (control), the PDMS-packaged sample, and PDMS dosed with 1 μM A.R. H₂O₂ or 1 μg/mL doxorubicin after treatment.

(a) Fluorescence images showing cell death by PI staining (red); (b) fluorescence images showing cell apoptosis by Annexin V staining (green); (c) histogram of the percentages of dead and apoptotic cells. All scale bars are 200 μm. The cell nuclei were stained by Hoechst 33342 or DAPI (blue). p < 0.05*; p < 0.005***.

Figure 7

(a) Tumor therapies by hydrogel as a function of time. Tumor growth curves of different groups after treatment. The tumor volumes were normalized to their initial sizes. (b) Photographs of the experimental (left) and control (right) sides of one mouse after nanomedicine treatment. (c–f) HE staining of tumor tissue of mice in one week.