Surface curvature-induced oriented assembly of sushi-like Janus therapeutic nanoplatform for combined chemodynamic therapy

Abstract

Background: Chemodynamic therapy (CDT) based on Fenton/Fenton-like reaction has emerged as a promising cancer treatment strategy. Yet, the strong anti-oxidation property of tumor microenvironment (TME) caused by endogenous glutathione (GSH) still severely impedes the effectiveness of CDT. Traditional CDT nanoplatforms based on core@shell structure possess inherent interference of different subunits, thus hindering the overall therapeutic efficiency. Consequently, it is urgent to construct a novel structure with isolated functional units and GSH depletion capability to achieve desirable combined CDT therapeutic efficiency.

Results: Herein, a surface curvature-induced oriented assembly strategy is proposed to synthesize a sushi-like novel Janus therapeutic nanoplatform which is composed of two functional units, a FeOOH nanospindle serving as CDT subunit and a mSiO₂ nanorod serving as drug-loading subunit. The FeOOH CDT subunit is half covered by mSiO₂ nanorod along its long axis, forming sushi-like structure. The FeOOH nanospindle is about 400 nm in length and 50 nm in diameter, and the mSiO₂ nanorod is about 550 nm in length and 100 nm in diameter. The length and diameter of mSiO₂ subunit can be tuned in a wide range while maintaining the sushi-like Janus structure, which is attributed to a Gibbs-free-energy-dominating surface curvature-induced oriented assembly process. In this Janus therapeutic nanoplatform, Fe³⁺ of FeOOH is firstly reduced to Fe²⁺ by endogenous GSH, the as-generated Fe²⁺ then effectively catalyzes overexpressed H₂O₂ in TME into highly lethal ·OH to achieve efficient CDT. The doxorubicin (DOX) loaded in the mSiO₂ subunit can be released to achieve combined chemotherapy. Taking advantage of Fe³⁺-related GSH depletion, Fe²⁺-related enhanced ·OH generation, and DOX-induced chemotherapy, the as-synthesized nanoplatform possesses excellent therapeutic efficiency, in vitro eliminating efficiency of tumor cells is as high as ~ 87%. In vivo experiments also show the efficient inhibition of tumor, verifying the synthesized sushi-like Janus nanoparticles as a promising therapeutic nanoplatform.

Conclusions: In general, our work provides a successful paradigm of constructing novel therapeutic nanoplatform to achieve efficient tumor inhibition.

Keywords: Asymmetric nanostructure; Chemodynamic therapy; Janus nanoparticles; Mesoporous; Nanocatalytic medicine.

Fig. 1

Schematic illustration of sushi-like Janus mesoporous nanoplatform for combination therapy of a tumor

Fig. 2

Characterizations of mesoporous FeOOH&mSiO₂ Janus nanoparticles. (A) Schematic illustration of the synthetic process of FeOOH&mSiO₂ Janus nanoparticles. (B, C) SEM and (D, E) TEM images with different magnifications of the obtained FeOOH&mSiO₂ Janus nanoparticles. (F) Nitrogen sorption isotherms and the pore size distribution of FeOOH&mSiO₂ Janus nanoparticles. (G) PXRD Patterns of pre-synthesized β-FeOOH and FeOOH&mSiO₂ Janus nanoparticles. (H) Elemental mapping of Fe, Si and O in the FeOOH&mSiO₂ Janus nanoparticles. Scale bar: 200 nm

Fig. 3

TEM images of FeOOH&mSiO₂ Janus nanoparticles synthesized in different reaction conditions. (A) 2.7 mM CTAB; (B) 6.9 mM CTAB; (C) 9.6 mM CTAB; (D) 13.7 mM CTAB; (E) 20.6 mM CTAB; (F) 27.4 mM CTAB; (G) 3% (v/v) NH₃·H₂O; (H) 4% (v/v) NH₃·H₂O; (I) 8% (v/v) NH₃·H₂O. All conditions are fixed as experiment section in Supporting Information except for the altered one. Scale bar: 200 nm

Fig. 4

Mechanism of surface curvature-induced oriented assembly. TEM images of products obtained at different reaction stages: fixed-sampling of reaction process. (A, D) 4 min. (B, E) 6 min. (C, F) 8 min. (G) Mechanistic analysis of radially winding growth behavior from the side view. (H) Mechanistic analysis of transversal growth from the front view. Scale bar: 200 nm

Fig. 5

Catalytic and drug-loading properties of FeOOH&mSiO₂ Janus nanoparticles. (A) Absorption curve of methylene blue (MB) under different catalytic conditions (10 mM GSH, 10 mM H₂O₂, 125 µg/mL FMS, 125 µg/mL FMS + 10 mM H₂O₂ and 125 µg/mL FMS + 10 mM H₂O₂ + 10 mM GSH, respectively) determined by UV-vis absorption spectroscopy after being co-incubated for 3 h. The inset picture is the optical photograph of experimental group placed in absorbance-descending order. (B) Time-dependent curve of MB degradation under different GSH concentrations (0, 1.0, 2.5, 5.0, 10.0 mM). The inset picture is the optical photograph of experimental group placed in absorbance-descending order. (C) GSH (1 mM) depletion by FeOOH&mSiO₂ Janus nanoparticles determined by UV-vis absorption spectroscopy with DTNB as a probe. (D) X-ray photoelectron spectroscopy analysis of FMS and GSH-treated FMS (upper the former, lower the latter). Fe²⁺ and Fe³⁺ refer to standard fit peaks. Original XPS signals are weak because of the low content of Fe element in FMS samples (~ 10%). GSH concentration: 10 mM. (E) Illustration of the Fe³⁺-Fe²⁺ reaction circulation, in which Fe³⁺ depletes GSH, Fe²⁺ catalyzes Fenton reaction and degrades MB. All conditions are fixed as the experiment section except for the altered one. MB concentration: 10 µg/mL. pH: 5.4

Fig. 6

In vitro therapeutic effect of FeOOH&mSiO₂ Janus nanoparticles conducted with 4T1 breast cancer cells. (A) Cell viability of 4T1 cells incubated with FMS/FMS-DOX/C-FMS under different conditions. (B) Confocal laser scanning microscopy (CLSM) images of DCFH-DA stained 4T1 cells after incubation with fresh medium and FMS with or without H₂O₂ and GSH after 8 h. (C) CLSM images of Calcein AM (green, live cells) and PI (red, dead cells) co-stained 4T1 cells after incubation with fresh medium, FMS/FMS-DOX with or without H₂O₂ and GSH for 12 h. (D) CLSM images of 4T1 cells stained with DAPI after incubation with FMS-DOX at different time points. (E) Flow cytometric quantitative analysis of Annexin V-FITC/PI co-stained 4T1 cells after co-incubation with FMS/FMS-DOX with or without H₂O₂ and GSH under weak acidic (pH 5.4) conditions for 12 h. The dosage of FMS and FMS-DOX in the in vitro experiments was all controlled at 200 µg/mL. The concentration of H₂O₂ and GSH in the in vitro experiments was all controlled at 10 mM. Scale bar: 100 μm

Fig. 7

In vivo therapeutic efficacy of FeOOH&mSiO₂ Janus nanoparticles conducted with 4T1-tumor-bearing mice. (A) Schematic illustration of tumor model establishment and treatment process. The nanocomposite was administered intravenously at 0, 2nd, 5th, 9th, 12th, 16th, 19th and 21st days. (B) Eventual tumor growth rate of 4T1 tumor-bearing mice treated with saline (control group), FMS, DOX and FMS-DOX calculated with dissected tumor weight (Normalized with the group treated with FMS-DOX). Data are expressed as mean standard ± errors (n = 3). (C) Tumor volume growth curves of 4T1 tumor-bearing mice treated with saline (control group), FMS, DOX and FMS-DOX. Data are expressed as mean standard ± errors (n = 3). (D) Body weights of tumor-bearing mice during treatments. Data are expressed as mean standard ± errors (n = 3). (E) H&E staining of tumor tissues harvested from corresponding mice after 21 days of treatments. Scale bar: 50 μm