Abstract
Photothermal cancer therapy has attracted considerable interest for cancer treatment in recent years, but the effective photothermal agents remain to be explored before this strategy can be applied clinically. In this study, we therefore develop flower-like molybdenum disulfide (MoS2) nanoflakes and investigate their potential for photothermal ablation of cancer cells. MoS2 nanoflakes are synthesized via a facile hydrothermal method and then modified with lipoic acid-terminated polyethylene glycol (LA-PEG), endowing the obtained nanoflakes with high colloidal stability and very low cytotoxicity. Upon irradiation with near infrared (NIR) laser at 808 nm, the nanoflakes showed powerful ability of inducing higher temperature, good photothermal stability and high photothermal conversion efficiency. The in vitro photothermal effects of MoS2-PEG nanoflakes with different concentrations were also evaluated under various power densities of NIR 808-nm laser irradiation, and the results indicated that an effective photothermal killing of cancer cells could be achieved by a low concentration of nanoflakes under a low power NIR 808-nm laser irradiation. Furthermore, cancer cell in vivo could be efficiently destroyed via the photothermal effect of MoS2-PEG nanoflakes under the irradiation. These results thus suggest that the MoS2-PEG nanoflakes would be as promising photothermal agents for future photothermal cancer therapy.
Highlights
Photothermal cancer therapy has attracted considerable interest for cancer treatment in recent years, but the effective photothermal agents remain to be explored before this strategy can be applied clinically
Chou et al first demonstrated the effectiveness of using single-layer chemically exfoliated MoS2 sheets as a novel NIR photothermal agent for Photothermal therapy (PTT), which exhibited greater absorbance in the NIR region than that of both graphene oxide (GO) and gold nanorods[35]
The preparation of MoS2-PEG nanoflakes is schematically illustrated in the Fig. 1A
Summary
After cells were treated with combined MoS2-PEG nanoflakes and laser irradiation, the CLSM image in Fig. 5Bd demonstrates that the red fluorescence was colocalized with green fluorescence of Lysotracker to yield orange-red staining throughout the entire cell It indicates that the MoS2-PEG nanoflakes combined with NIR laser irradiation can effectively destroy the lysosomal membranes and cause a rapid leakage of AO staining of acidic organelles, which will lead to acute cell death. Relative to an blank control with only saline injection (Fig. 5Ea), in the case of MoS2-PEG nanoflakes-injected mice, histological examination of the tumors treated with showed common signs of thermal cell damage under 1 W/cm[2] NIR 808 nm laser irradiation, such as loss of contact, shrinkage of the cells, pyknotic and fragmentized nuclei (Fig. 5Ed) Taken together, these results unambiguously proof photothermal effects of MoS2-PEG nanoflakes. Further cellular and in vivo studies are required, the synthesized MoS2-PEG nanoflakes clearly showed good colloidal and photothermal stability, very low cytotoxicity and effective photothermal ablation of cancer cells, which would be promising materials for future PTT applications
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