Black Phosphorus Nanosheets for Mild Hyperthermia-Enhanced Chemotherapy and Chemo-Photothermal Combination Therapy

Abstract

Near-infrared (NIR) light triggered photothermally enhanced cellular internalization strategy shows great potential to improve antitumor effect to fight against cancer. In this work, a black phosphorus (BP) nanosheet-based nanomedicine, which is composed of BP nanosheet, human serum albumin (HSA) and paclitaxel (PTX), was developed for mild hyperthermia-enhanced intracellular drug delivery and chemo-photothermal combination therapy. BP nanosheet was successfully synthesized by a one-pot biomimetic synthesis method using HSA as exfoliating agent and capping agent. Meanwhile, PTX can be efficiently loaded by HSA via hydrophobic interactions. The PTX-loaded HSA functionalized BP (BP-HSA-PTX) exhibits great photothermal performance, excellent biodegradability/biocompatibility, and effective drug loading. Upon NIR laser illumination, mild hyperthermia (~43 °C) or photothermal effect can be achieved to improve the intracellular drug delivery efficiency and antitumor effect of BP-HSA-PTX. Our results indicate that HSA-functionalized BP has great potential for the loading, delivery, cellular uptake enhancement of chemotherapeutics and chemo-photothermal combination antitumor effect.

Keywords: black phosphorus nanosheets; combination therapy.; enhanced chemotherapy; mild hyperthermia; photothermal.

Figure 1

Preparation and characterization of the BP-HSA-PTX: (A) Preparation process; (B) TEM image; (C) HR-TEM image; (D) Element mapping; (E) AFM image of HSA; (F) AFM image of BP-HSA-PTX; (G) Height profiles along the white lines in Fig. 1F.

Figure 2

(A) TGA of BP, HSA and BP-HSA. (B) Photographs of BP-HSA-PTX dispersed in water (i), PBS (ii) and DMEM + 10% FBS (iii). (C) Time-dependent changes in absorption spectra of BP-HSA-PTX solution. Inset: photographs of BP-HSA-PTX dispersed in water for different times. (D) Absorbance spectra of BP-HSA-PTX supernatant. Inset: The absorbance of BP-HSA-PTX at a wavelength of 808 nm as a function of the concentration.

Figure 3

(A) Photothermal heating curves of pure water and the BP-HSA-PTX supernatants upon irradiation of an 808 nm laser (1.0 W/cm²). (B) Photothermal heating curves of the BP-HSA-PTX (0.1 mg/mL) upon irradiation of an 808 nm laser at different power densities. (C) Heating of the BP-HSA-PTX supernatant for five laser on/off cycles. (D) Absorption spectra of BP-HSA-PTX before and after five laser on/off cycles. (E) Photothermal heating curve of the BP-HSA-PTX aqueous solution upon 808 nm laser irradiation (1.0 W/cm²) and then the laser was shut off. F) Linear time data versus - ln θ obtained from the cooling stage of Figure 3E.

Figure 4

Schematic illustration (A) showing the photothermally enhanced cellular uptake of BP-HSA-PTX. Confocal images of U87MG cells incubated with PBS (B), FITC-labeled BP-HSA-PTX without (C) or with (D) NIR light irradiation (30 min). The temperature of cell medium was maintained at 42.5 ± 0.5 °C by adjusting the power density. (E) Mean FITC fluorescence intensity determined in cells in Figure 4B-D.

Figure 5

Viability of U87MG cells after incubation with BP-HSA for 24 h.

Figure 6

(A) Relative viabilities of U87MG cells after incubation with different samples with or without NIR light irradiation (30 min) and then washed with PBS and reincubated in fresh cell medium for 24 h. (B) Fluorescence images of Calcein AM/PI costained U87MG cells after different treatments.

Figure 7

Relative viabilities of U87MG cells incubated with BP-HSA or BP-HSA-PTX (0.4 mg/mL) after laser irradiation at different power densities for 5 min.