Near-Infrared Driven Gold Nanoparticles-Decorated g-C3N4/SnS2 Heterostructure through Photodynamic and Photothermal Therapy for Cancer Treatment

Abstract

Background: Phototherapy based on photocatalytic semiconductor nanomaterials has received considerable attention for the cancer treatment. Nonetheless, intense efficacy for in vivo treatment is restricted by inadequate photocatalytic activity and visible light response.

Methods: In this study, we designed a photocatalytic heterostructure using graphitic carbon nitride (g-C₃N₄) and tin disulfide (SnS₂) to synthesize g-C₃N₄/SnS₂ heterostructure through hydrothermal process. Furthermore, Au nanoparticles were decorated in situ deposition on the surface of the g-C₃N₄/SnS₂ heterostructure to form g-C₃N₄/SnS₂@Au nanoparticles.

Results: The g-C₃N₄/SnS₂@Au nanoparticles generated intense reactive oxygen species radicals under near-infrared (NIR) laser irradiation through photodynamic therapy (PDT) pathways (Type-I and Type-II). These nanoparticles exhibited enhanced photothermal therapy (PTT) efficacy with high photothermal conversion efficiency (41%) when subjected to 808 nm laser light, owing to the presence of Au nanoparticles. The in vitro studies have indicated that these nanoparticles can induce human liver carcinoma cancer cell (HepG2) apoptosis (approximately 80% cell death) through the synergistic therapeutic effects of PDT and PTT. The in vivo results demonstrated that these nanoparticles exhibited enhanced efficient antitumor effects based on the combined effects of PDT and PTT.

Conclusion: The g-C₃N₄/SnS₂@Au nanoparticles possessed enhanced photothermal properties and PDT effect, good biocompatibility and intense antitumor efficacy. Therefore, these nanoparticles could be considered promising candidates through synergistic PDT/PTT effects upon irradiation with NIR laser for cancer treatment.

Keywords: Gold nanoparticles; Photodynamic therapy; Photothermal therapy; SnS2; g-C3N4.

Scheme 1

Schematic diagram for synthesis of g-C₃N₄/SnS₂@Au nanoparticles and its synergistic PDT/PTT effects for cancer therapeutics.

Figure 1

TEM images of (A) g-C₃N₄. (B) g-C₃N₄/SnS₂. (C) g-C₃N₄/SnS₂@Au nanoparticles. (D) EDS mapping of g-C₃N₄/SnS₂@Au nanoparticles.

Figure 2

(A) FTIR spectra of g-C₃N₄, SnS₂, g-C₃N₄/SnS₂, and g-C₃N₄/SnS₂@Au nanoparticles. (B) UV-Vis-NIR absorption spectra of g-C₃N₄, SnS₂, g-C₃N₄/SnS₂, and g-C₃N₄/SnS₂@Au nanoparticles. (C) The corresponding band gap of g-C₃N₄ and SnS₂.

Figure 3

XPS spectra of g-C₃N₄/SnS₂@Au nanoparticles for (A) C 1s. (B) N 1s. (C) Sn 3d. (D) S 2p. (E) Au 4f.

Figure 4

(A) The photothermal properties of g-C₃N₄/SnS₂@Au nanoparticles at various concentrations exposed to 808 nm laser. (B) The photothermal stability of g-C₃N₄/SnS₂@Au nanoparticles exposed to 808 nm laser over three on/off cycles. (C) The MB activity of g-C₃N₄/SnS₂@Au nanoparticles measured at various exposure times. (D) ROS detection monitored using DCFH-DA fluorescence spectra treated with different irradiation times of g-C₃N₄/SnS₂@Au nanoparticles (808 nm, 1 W/cm²). (E) Absorbance spectra of DPBF mixed with g-C₃N₄/SnS₂@Au nanoparticles for various laser irradiations.

Figure 5

(A) Viability of normal fibroblast cells (L929) at different concentrations of g-C₃N₄/SnS₂@Au nanoparticles. (B) Cytotoxicity of human liver carcinoma cancer (HepG2) cells treated with g-C₃N₄/SnS₂@Au nanoparticles at various concentrations with or without 808 nm laser irradiation (1 W/cm², 5 min). (C) Bright field images of HepG2 incubated with g-C₃N₄/SnS₂@Au nanoparticles for various incubation times (1) 0.5 h, (2) 1 h, and (3) 4 h. (D) Cellular uptake of HepG2 cells treated with g-C₃N₄/SnS₂@Au stained with DAPI for different incubation times (1) 0.5 h, (2) 1 h, and (3) 4 h. (E) Fluorescence images of HepG2 cells stained with DCFH-DA (1) control, (2) g-C₃N₄/SnS₂@Au, and (3) g-C₃N₄/SnS₂@Au nanoparticles with 808 nm laser irradiation (*** denote p < 0.001 and ns denotes no significant difference).

Figure 6

(A) Infrared imaging of tumor-bearing mice for control and g-C₃N₄/SnS₂@Au nanoparticles subjected with an 808 nm laser. (B) Tumor volume and (C) body weight analysis of mice with different treatment groups control, g-C₃N₄/SnS₂@Au and g-C₃N₄/SnS₂@Au under 808 nm laser irradiation. (D) H&E staining images of tumor after various treatment groups control, g-C₃N₄/SnS₂@Au and g-C₃N₄/SnS₂@Au with irradiation of 808 nm laser (*** denote p < 0.001, scale bar = 100 µm).

Figure 7

H&E-stained images of the main organs from various treatment groups (scale bar = 100 µm).