Redox/NIR dual-responsive MoS2 for synergetic chemo-photothermal therapy of cancer

Abstract

Background: The construction of a multifunctional drug delivery system with a variety of advantageous features, including targeted delivery, controlled release and combined therapy, is highly attractive but remains a challenge.

Results: In this study, we developed a MoS₂-based hyaluronic acid (HA)-functionalized nanoplatform capable of achieving targeted delivery of camptothecin (CPT) and dual-stimuli-responsive drug release. HA was connected to MoS₂ via a disulfide linkage, forming a sheddable HA shell on the surface of MoS₂. This unique design not only effectively prevented the encapsulated CPT from randomly leaking during blood circulation but also significantly accelerated the drug release in response to tumor-associated glutathione (GSH). Moreover, the MoS₂-based generated heat upon near-infrared (NIR) irradiation could further increase the drug release rate as well as induce photothermal ablation of cancer cells. The results of in vitro and in vivo experiments revealed that MoS₂-SS-HA-CPT effectively suppressed cell proliferation and inhibited tumor growth in lung cancer cell-bearing mice under NIR irradiation via synergetic chemo-photothermal therapy.

Conclusions: The as-prepared MoS₂-SS-HA-CPT with high targeting ability, dual-stimuli-responsive drug release, and synergistic chemo-photothermal therapy may provide a new strategy for cancer therapy.

Keywords: Chemo-photothermal therapy; Disulfide linkage; Dual-stimuli-responsive drug release; HA; MoS2 nanosheets.

Fig. 1

Synthesis and characterization of MoS₂–SS–HA nanosheets. a Schematic of the synthesis of MoS₂–SS–HA as a carrier capable of achieving targeted delivery of CPT and controlled drug release under dual stimuli for synergetic chemo-photothermal cancer therapy. (i, ii) Chemical exfoliation of MoS₂ crystals to single-layered MoS₂ nanosheets and synthesis of sulfhydrylated HA, (iii) conjugation of MoS₂ with HA via a disulfide linkage, (iv) the CPT loading process, (v) intravenous administration of MoS₂–SS–HA–CPT and efficient accumulation of the nanosheets at the tumor site based on passive and active targeting, and (vi) cellular uptake of HA-grafted MoS₂ nanosheets, rapid intracellular drug release, and synergetic chemo-photothermal therapy: (1) cellular uptake of MoS₂–SS–HA–CPT via HA-receptor-mediated endocytosis; (2) MoS₂-based generated hyperthermia upon NIR irradiation; (3) and (4) redox- and NIR-triggered drug release; and (5) and (6) hyperthermia-induced photothermal therapy and CPT-mediated chemotherapy. b FT-IR spectra of MoS₂ before and after HA coating. c AFM images of MoS₂ and MoS₂–SS–HA. d Stability of MoS₂ and MoS₂–SS–HA suspensions in water, PBS, and cell medium for 1 week

Fig. 2

a–f Size-time dependence of MoS₂–SS–HA when dispersed in PBS, cell medium, and water with different GSH concentrations, as determined by DLS measurements

Fig. 3

Photothermal performance of MoS₂–SS–HA and redox/NIR light dual-stimuli-responsive drug release. a Temporal temperature elevation of MoS₂–SS–HA suspensions (12.5, 25, 50, and 100 μg/mL) upon NIR irradiation (1 W/cm²). b Temperature profile of a MoS₂–SS–HA suspension (100 μg/mL) irradiated with an 808-nm laser at 1 W/cm² for 600 s, followed by natural cooling without irradiation. c Linear time data versus − Lnθ obtained from the cooling time of b. d UV–vis–NIR spectra of CPT-loaded MoS₂–SS–HA nanosheets. e, f GSH- and NIR light-triggered drug release from MoS₂–SS–HA–CPT in PBS (pH 7.4)

Fig. 4

Biocompatibility of MoS₂–SS–HA. a Percentages of RBC hemolysis induced by MoS₂–SS–HA at various concentrations. Inset: images for direct observation of hemolysis. b Viabilities of A549 and HELF cells after incubation with cell medium containing various concentrations of MoS₂–SS–HA for 48 h

Fig. 5

Cellular uptake of HA-grafted MoS₂ nanosheets and intracellular cargo release. Nano: MoS₂–SS–HA. a Confocal images of A549 and HELF cells incubated with MoS₂–SS–HA–RB ([RB] = 40 μg/mL) for 2 h in the absence and presence of excess free HA. b Confocal images showing dual-stimuli (GSH and NIR light)-triggered intracellular cargo release. After treatment with GSH-OEt for 2 h, A549 cells were incubated with cell medium containing MoS₂–SS–HA–RB ([RB] = 40 μg/mL) for another 2 h, washed with PBS, and irradiated with an 808-nm laser (1 W/cm²) for 10 min. Samples not exposed to a stimulus were used as the control. c, d Flow cytometry analysis of the intracellular fluorescence in a and b

Fig. 6

MoS₂–SS–HA–CPT for synergetic chemo-photothermal cancer therapy in vitro. a Viabilities of A549 cells pretreated with GSH-OEt (0 or 10 mM) after incubation with free CPT or MoS₂–SS–HA–CPT. A549 cells were treated with cell medium containing GSH-OEt (0 or 10 mM) for 2 h. After this treatment, the cells were incubated with free CPT or MoS₂–SS–HA–CPT at different CPT concentrations for 2 h, washed with PBS, and then incubated for another 48 h before the MTT assay. The data are expressed as the mean ± SD (n = 5) and were analyzed via ANOVA. *p < 0.05, **p < 0.01. b Viabilities of GSH-OEt-treated and non-GSH-OEt-treated A549 cells incubated with free CPT, MoS₂–SS–HA, or MoS₂–SS–HA–CPT for 2 h, followed by NIR irradiation and incubation for an additional 48 h before the MTT assay. The data are expressed as the mean ± SD (n = 6) and were analyzed via ANOVA. ^##p < 0.01. c Phase-contrast images of A549 cells after several of the treatments mentioned in a and b

Fig. 7

Biodistribution of MoS₂–SS–HA–CPT in lung-cancer-cell-bearing mice. a Tissue biodistribution of Mo in major organs 6, 12, 24, and 48 h after intravenous administration of MoS₂–SS–HA–CPT at a dose of 1.2 mg/kg. b Mo level in the tumors at 6, 12, 24, and 48 h after intravenous administration of MoS₂–SS–HA–CPT with or without preinjection of free HA (50 mg/kg). The data are expressed as the mean ± SD (n = 3) and were analyzed by ANOVA. *p < 0.05, **p < 0.01

Fig. 8

MoS₂–SS–HA–CPT for synergetic chemo-photothermal cancer therapy in vivo. (i) PBS, (ii) CPT, (iii) MoS₂–SS–HA + NIR, (iv) MoS₂–SS–HA–CPT, and (v) MoS₂–SS–HA–CPT + NIR. a In vivo thermal images of A549 tumor-bearing mice injected intravenously with PBS, CPT, MoS₂–SS–HA, and MoS₂–SS–HA–CPT under NIR irradiation. b Temperature changes in tumors in groups (i), (ii), (iii), and (v) during NIR irradiation. c Body weights of mice in each group as a function of time. d Tumor growth curves of each group after various treatments. Significant differences appeared between the MoS₂–SS–HA–CPT + NIR group and the other groups and are marked as **p < 0.01. e Tumor growth inhibition ratio of the experimental groups. Significant differences appeared between the MoS₂–SS–HA–CPT + NIR group and the other experimental groups and are marked as **p < 0.01. f Photographs of tumors collected from the five groups after 24 days. g Tumor weights in each group. Significant differences appeared between the MoS₂–SS–HA–CPT + NIR group and the other groups and are marked as **p < 0.01. h HE images of major organs collected from mice after 24 days of intravenous administration of PBS and MoS₂–SS–HA–CPT