Single‐Layer MoS₂ Nanosheets with Amplified Photoacoustic Effect for Highly Sensitive Photoacoustic Imaging of Orthotopic Brain Tumors

Abstract

Photoacoustic (PA) imaging, as a fast growing technology that combines the high contrast of light and large penetration depth of ultrasound, has demonstrated great potential for molecular imaging of cancer. However, PA molecular imaging of orthotopic brain tumors is still challenging, partially due to the limited options and insufficient sensitivity of available PA molecular probes. Here, the direct formation of single-layer (S-MoS 2 ), few-layer (F-MoS 2 ), and multi-layer (M-MoS 2 ) nanosheets by the albumin-assisted exfoliation without further surface modifications is reported. It is demonstrated that the PA effect of the MoS 2 nanosheets is highly dependent on their layered nanostructures. Decreasing the number of nanosheet layers from M-MoS 2 to S-MoS 2 can both significantly enhance the near-infrared light absorption and improve the elastic properties of the nanomaterial, resulting in greatly amplified PA effect. The in vitro experiments demonstrate that the prepared S-MoS 2 with excellent biocompatibility can be efficiently internalized into U87 glioma cells, producing strong PA signals for highly sensitive detection of brain tumor cells, with a detection limit of ≈100 cells. Intravenous administration of S-MoS 2 to both U87 subcutaneous and orthotopic tumor-bearing mice shows highly efficient tumor retention and significantly enhanced PA contrast. Tumor tissue ≈1.5 mm below the skull can still be clearly visualized in vivo. Previous studies suggest that the fabricated S-MoS 2 with amplified PA effect have high potential to serve as an efficient nanoplatform for sensitive PA molecular imaging and hold promising prospect for translational medicine.

Cobalt Phosphide Nanoparticles Applied as a Theranostic Agent for Multimodal Imaging and Anticancer Photothermal Therapy

“…Besides IRT imaging and PTT, the high NIR absorbance and significant photothermal conversion property endowed the CoP NPs great potentials for PA imaging, which is a noninvasive imaging modality based on thermal expansion‐induced ultrasonic signals with multiple well‐demonstrated advantages, such as deep tissue penetration, high spatial sensitivity, and high resolution . To explore their PA imaging capacity in vitro, the PA signal intensity of the NPs aqueous dispersions at gradient concentrations (0–160 µg mL −1 ) was scanned under the PA tomography system.…”

Two‐Dimensional Nanomaterials for Photothermal Therapy

“…In addition, the optical absorption is influenced by excitonic transitions, because of the strong interactions between electrons and holes. In a study by Zheng and co‐workers, the optical absorption of single‐layer, few‐layer, and multi‐layer MoS 2 nanosheets were compared, and the optical absorbance of single‐layer MoS 2 were the highest, which was attributed to direct excitonic transitions at the K‐point of the Brillouin zone . Moreover, the size of MoS 2 nanosheets can also affect their optical properties.…”

Advanced Near‐Infrared Light‐Responsive Nanomaterials as Therapeutic Platforms for Cancer Therapy

“…[198] Hydrothermal reaction of WCl 6 and MCl x in oleylamine and 1-octadecene produced Reproduced with permission. [209] Copyright 2016, Wiley-VCH. C) In vivo photoacoustic images of orthotopic brain tumor region before (Pre) and after intravenous injection of S-MoS 2 .…”

“…Overall, this strategy may allow a reduction in doses of iron oxides, magnetic field strength, and NIR excitation power to comply with in vivo settings. TiO 2-x treatment with 808 nm (1 W cm −2 ) irradiation www.advancedsciencenews.com www.advtherap.com MoS 2 Exfoliation Chitosan 80 nm (l) 4-6 nm (t) -PTT, drug delivery, CT imaging [187] MoS 2 Exfoliation -14.7 nm (hd) -PDT, down-and upconversion fluorescence Imaging [188] MoS 2 Exfoliation LA-PEG 50 nm (l) 2 nm (t) 28.4 L g −1 cm −1 at 800 nm PTT, drug delivery [191] MoS 2 Exfoliation BSA 89 nm (l) 5-15 nm (t) -PTT, drug delivery [192] MoS 2 Ionic liquid grinding Chitosan 120 nm (l) 1.4 nm (t) 62.6 L g −1 cm −1 at 800 nm PTT [194] MoS 2 Solvothermal PEG 79.2 nm (l) 0.29 nm (t) -PTT [197] MoS 2 Exfoliation -0.8 µm (l) 1.6 nm (t) 29.2 L g −1 cm −1 at 800 nm PTT [199] MoS 2 Solvothermal LA-PEG 90 nm (l) -PTT [201] MoS 2 Hydrothermal Polyacrylic acid LA-PEG 90 nm (l) -PTT [203] MoS 2 Sonication BSA 181 ± 3 nm (l) (hd) 10.65 nm (t) -PA imaging [209] MoS 2 Exfoliation DMSA-IONP-PEG-Amine LA-PEG 50-200 nm (l) -PTT, PA, MRI, and PET imaging [211] MoS 2 Hydrothermal Fe 3 O 4 PEG 190.1 nm (hd) -PTT, PA, and MRI imaging [213] MoS 2 Solvothermal Polyaniline PEG 21.5 ± 3.9 nm (hd) -PTT, RT, PA, and CT imaging [215] MoS 2 Exfoliation PEG-amine Mesoporous silica DOX 450 nm (hd) -PTT, drug delivery [223] MoS 2 Exfoliation PEI-HA DOX NOTA-64 Cu 30-50 nm (l) 5-7 nm (t) -PTT, drug delivery [224] MoS 2 Solvothermal PLGA oleosol DOX 100 nm (l) -PTT, drug delivery [225] MoS 2 Exfoliation LA-PEG PEI 90 nm (hd) -PTT, gene delivery [226] MoS 2 Exfoliation LA-PEI SH-PEG 100-150 nm (l) 6-8 nm (t) -PTT, gene delivery [227] MoS 2 Hydrothermal Gen 5 polyamidoamine (PAMAM) 420 nm (hd) -PTT, gene delivery [230] MoS 2 Exfoliation LA-PEG 100 nm (hd) 28.4 L g −1 cm −1 at 800 nm PTT, PDT, and PA imaging [231] MoS 2 Hydrothermal PEI Fe 3 O 4 ICG Pt(IV) 80 nm (hd) -PTT, PDT, PA, MRI imaging [234] WS 2 Exfoliation LA-PEG 3 ± 0.18 nm (l) -PTT, RT, PA, and CT imaging [179c] WS 2 Exfoliation BSA 20-100 nm (l) 4-5 nm (t) 21.8 L g −1 cm −1 at 808 nm PTT, PDT, and CT Imaging [186] WS 2 Exfoliation LA-PEG 50-100 nm (l) 1.6 nm (t) 23.8 L g −1 cm −1 at 808 nm PTT, PA, and CT imaging [189] WS 2 High-temperature reaction Gd 3+ C 18 PMH-PEG 90-100 nm (hd) 22.6 L g −1 cm −1 at 808 nm PTT, ...…”