Nanocomposite plasters for the treatment of superficial tumors by chemo-photothermal combination therapy

Abstract

Introduction: Novel nanomedical systems are being developed as multiple therapeutic modalities because the combinational therapies for cancer on a single platform can have larger chance to address tumor heterogeneity and drug resistance than any mono-therapeutic modality.

Methods: In this study, photothermal therapy (PTT) and chemotherapy (CT) were combined to treat squamous cell carcinoma by using a novel type of noninvasive plaster composed of carboxylated-reduced graphene oxide (rGO-COOH), gold nanorods (Au NRs), and doxorubicin (DOX). Firstly, DOX was loaded onto rGO-COOH to form DOX_rGO-COOH. Then, the obtained DOX_rGO-COOH and Au NRs were co-assembled to obtain nanocomposite multilayer. rGO-COOH and Au NRs were combined together to obtain high light-to-heat conversion efficiency. Using them as photothermal agents for PTT and using DOX in rGO-COOH as an anticancer drug for CT, their synergistic combination therapy could be applicable practically.

Results: As a result, DOX_rGO-COOH/Au NRs showed higher photothermal effects than that showed by rGO-COOH or Au NRs alone. It also showed higher therapeutic effects than DOX_rGO-COOH (for CT) or Au nr (for PTT) alone. Moreover, the system can repeatedly produce heat and simultaneously stimulate the release of the encapsulated anticancer drug into the tumor upon being irradiated by near-infrared laser. In vivo experiments demonstrated that the squamous cell carcinoma-bearing mice treated with DOX_rGO-COOH/Au NRs were healthy for more than 60 days without tumor recurrence.

Conclusion: The as-developed DOX_rGO-COOH/Au NRs plaster could be an effective, convenient, and noninvasive treatment option for treating superficial tumors.

Keywords: Au nanorods; carboxylated-reduced graphene oxide; doxorubicin; nanocomposite plaster; superficial tumor.

Figure 1

(A) FTIR spectra of GO and rGO–COOH; (B) UV-Vis spectra of Au NRs, DOX, DOX_rGO–COOH, DOX_rGO–COOH/Au NRs, and rGO–COOH; (C) TEM image of Au NRs. The scale bar is 100 nm; (D) high-resolution TEM image of Au NRs. Abbreviations: Au NRs, gold nanorods; DOX, doxorubicin; FTIR, Fourier transform infrared spectroscopy; GO, graphene oxide; rGO–COOH, carboxylated-reduced GO; TEM, transmission electron microscope; UV-Vis, ultraviolet–visible spectrophotometry.

Figure 2

(A) The release profile over time of DOX_rGO–COOH and (DOX_rGO–COOH/Au NRs)₄ in PBS with NIR radiation and without NIR radiation (808 nm, 0.7 W cm⁻²), respectively. Each radiation lasted 10 minutes. (B) The cumulative release of DOX is profiled over DOX_rGO–COOH/Au NRs layer number after seven discontinued laser radiations. Abbreviations: Au NRs, gold nanorods; DOX, doxorubicin; NIR, near infrared; rGO–COOH, carboxylated-reduced graphene oxide.

Figure 3

(A) Change in temperature of rGO–COOH, Au NRs, and (rGO–COOH/Au NRs)₄ in water after NIR radiation (808 nm, 0.7 W cm⁻²). Pure water was irradiated similarly as a control. (B) The temperature changes of the rGO–COOH/Au NRs multilayer are profiled over layer number after 10 minutes radiation. Abbreviations: Au NRs, gold nanorods; NIR, near infrared; rGO–COOH, carboxylated-reduced graphene oxide.

Figure 4

(A) Cell viabilities of A-431 cells in different groups with or without NIR radiation assessed by CCK-8 assay. The groups included (1) TCPS, (2) blank glass slide, (3) rGO–COOH, (4) Au NRs, (5) rGO–COOH/Au NRs, (6) DOX_rGO–COOH, and (7) DOX_rGO–COOH/Au NRs. (B) Confocal images of A-431 cells cultured in different groups stained by Ca-AM and PI after NIR radiation. The live and dead cells were stained simultaneously with green and red fluorescence, respectively. The scale bars are all 100 µm. Top: blank glass slide, blank glass slide + NIR; middle: rGO–COOH + NIR, Au NRs + NIR, rGO–COOH/Au NRs + NIR; bottom: DOX_rGO–COOH + NIR, DOX_rGO–COOH/Au NRs + NIR. Abbreviations: Au NRs, gold nanorods; DOX, doxorubicin; rGO–COOH, carboxylated-reduced graphene oxide; NIR, near infrared.

Figure 5

(A) The relative tumor size of mice in different treatment groups with or without NIR radiation. (B) The change in mouse body weight ratios in different treatment with or without NIR radiation. (C) Representative photographs of the mice at different times after treatment with DOX_rGO–COOH/Au NRs under NIR radiation. Abbreviations: Au NRs, gold nanorods; DOX, doxorubicin; rGO–COOH, carboxylated-reduced graphene oxide; NIR, near infrared.

Figure 5

(A) The relative tumor size of mice in different treatment groups with or without NIR radiation. (B) The change in mouse body weight ratios in different treatment with or without NIR radiation. (C) Representative photographs of the mice at different times after treatment with DOX_rGO–COOH/Au NRs under NIR radiation. Abbreviations: Au NRs, gold nanorods; DOX, doxorubicin; rGO–COOH, carboxylated-reduced graphene oxide; NIR, near infrared.

Figure 6

Images of H&E-stained tumor sections collected from the mice bearing tumors after various treatments including DOX_rGO–COOH + NIR radiation, rGO– COOH/Au NRs + NIR radiation, and DOX_rGO–COOH/Au NRs + NIR radiation. The tumors were also collected from the two control groups and the group only receiving NIR radiation. Abbreviations: Au NRs, gold nanorods; DOX, doxorubicin; rGO–COOH, carboxylated-reduced graphene oxide; NIR, near infrared.

Scheme 1

Schematic representation of the fabricated plaster composed of DOX_rGO–COOH and Au NRs and it’s in vivo application. Abbreviations: Au NRs, gold nanorods; DOX, doxorubicin; rGO–COOH, carboxylated-reduced graphene oxide; NIR, near infrared.