Bubble-generating polymersomes loaded with both indocyanine green and doxorubicin for effective chemotherapy combined with photothermal therapy.

UNLABELLED

The combination of chemotherapy and photothermaltherapy (PTT) via stimuli-responsive nanovesicles has great potential in tumor treatment. In the present study, bubble-generating polymersomes, which can generate bubbles in response to low pH or hyperthermia, were fabricated to simultaneously encapsulate chemotherapeutic drug and photosensitizing agent for the synergistic chemo-photothermal tumor therapy. Photosensitizer indocyanine green (ICG) was encapsulated into the bilayer of polymersomes formed by amphiphilic triblock copolymer PCL-PEG-PCL through thin film re-hydration method, while chemotherapeutic doxorubicin (DOX) was loaded into the hydrophilic lumen using a transmembrane ammonium bicarbonate gradient loading procedure. Under acidic condition or laser irradiation, the ammonium bicarbonate (NHHCO) encapsulated in the bubble-generating DOX-ICG-co-delivery polymersomes (BG-DIPS) would decompose to produce CO bubbles, resulting in destruction of vesicle structure and rapid drug release. In vitro drug release study confirmed that acidic environment and NIR laser irradiation could accelerate DOX release from the BG-DIPS. Cellular uptake study indicated that laser-induced hyperthermia highly enhanced endocytosis of BG-DIPS into 4T1-Luc cancer cells. In vitro cytotoxicity study demonstrated that BG-DIPS exhibited much higher cytotoxicity than free drugs under laser irradiation. In vivo biodistribution study indicated that BG-DIPS could accumulate in the tumor region, prolong drug retention, and increase photothermal conversion efficiency. Furthermore, in vivo antitumor study showed that BG-DIPS with laser irradiation efficiently inhibited 4T1-Luc tumor growth with reduced systemic toxicity. Hence, the formulated bubble-generating polymersomes system was a superior multifunctional nanocarrier for stimuli-response controlled drug delivery and combination chemo-photothermal tumor therapy.

STATEMENT OF SIGNIFICANCE

The combination of chemotherapy and photothermaltherapy via stimuli-responsive nanovesicles has great potential in tumor treatment. Herein, bubble-generating polymersomes, which can generate bubbles in response to low pH or hyperthermia, were fabricated to simultaneously encapsulate chemotherapeutic drug (DOX) and photosensitizing agent (ICG) for the synergistic chemo-photothermal tumor therapy. The results in vitro and in vivo demonstrated that bubble-generating DOX-ICG-co-delivery polymersomes (BG-DIPS) would accelerate DOX release from the BG-DIPS and accumulate in the tumor region, prolong drug retention, and increase photothermal conversion efficiency. BG-DIPS with laser irradiation could efficiently inhibited 4T1-Luc tumor growth with reduced systemic toxicity. Hence, the formulated bubble-generating polymersomes system was a superior multifunctional nanocarrier for stimuli-response controlled drug delivery and combination chemo-photothermal tumor therapy.