Water-Responsive Hybrid Nanoparticles Codelivering ICG And DOX For Breast Cancer Treatment

Breast cancer is one of the malignant tumors that severely threaten the lives of people all over the world and can be treated well upon early diagnosis;however,it becomes almost fatal after being metastasized to distant organs in the late stage.Commonly,chemotherapy is the standard treatment for breast cancer patients after surgery.However,rapid clearance and nonspecific biodistribution of the chemotherapeutic agents in vivo result in severe toxicity and low therapeutic effects,which limits their further application.Although selective accumulation of DDSs in the tumor sites can be easily achieved via EPR effects,the therapeutic efficacy remains unsatisfying due to the insufficient drug release and the poor tumor penetration of DDSs.Collectively,breast cancer therapy that relies on single chemotherapy fails to achieve better therapeutic efficacy.Therefore,Designing DDSs that effectively enhancing drug penetration and achieving bust drug release in tumors is the key to improve the therapeutic effect.Our study explored nanosized amorphous calcium carbonate.High aqueous instability of amorphous calcium carbonate is responsible for its bust drug release in aqueous medium.We constructed reformative phospholipid-calcium-carbonate hybrid nanoparticles that were surface modified with phospholipid(PL)and the polymer polyethylene glycol,capable of isolating the amorphous calcium carbonate from the exterior aqueous medium and improve its biological properties.First,the anticancer drug doxorubicin(DOX)and a photosensitizer indocyanine green(ICG)were incorporated into amorphous calcium carbonate as the water-responsive cores(ACC-DOX&ICG),then PL was coated on the surface of the ACC-DOX&ICG as the protective shell(PL/ACC-DOX&ICG).The particle size and zeta potential of PL/ACC-DOX&ICG were 100 ±3.7 nm and-20.1 ±0.9 mV.Transmission electron microscopy showed PL/ACC-DOX&ICG were apparent membrane-core structure with uniform spherical shape.Release experiments were performed using different pH phosphate buffers in order to evaluate the detailed drug release profile of PL/ACC-DOX&ICG under different intracorporeal conditions.It was shown that ACC-DOX&ICG under three different pH PBS showed significant water-sensitive release characteristics,and the cumulative release of DOX was more than 80%at 8 h;while PL/ACC-DOX&ICG had a slow release of DOX due to the protective effect of surface phospholipids.When the PL/ACC-DOX&ICG was taken up by the tumor cells,the surface phospholipid layer was hydrolyzed by the intracellular lipase,so the water-sensitive release property could be achieved.Which demonstrated that the proposed drug locking and ACC-DOX&ICG preserving effect were successfully realized by PL modification.The results of in vitro cytotoxicity experiments showed that the ICG-induced photothermal effect combined with the anti-tumor effect of DOX in PL/ACC-DOX&ICG significantly enhanced the toxicity of tumor cells;IC50 value was 1.5 ?g/mL,which was significantly lower than PL/ACC-DOX&ICG or PL/ACC-ICG with irradiation.Cell uptake experiments showed that after uptaking of PL/ACC-DOX&ICG by 4T1 cells,the nanoparticles could be rapidly disintegrated to release free DOX molecules.The results of laser confocal microscopy showed that ICG-induced hyperthermia significantly enhanced the uptake of PL/ACC-DOX&ICG by 4T1 cells;Quantitative determination of PL/ACC-DOX&ICG in near-infrared light,the intake increased to 2.4 times than PL/ACC-DOX&ICG after uptaking of 4 h.At the same time,the results of tumor penetration capability of PL/ACC-DOX&ICG in 4T1 multicellular spheroids(MCTs)showed that hyperthermia enhanced the penetration depth of PL/ACC-DOX&ICG in MCTs.The volume inhibition rate of cell sphere treating by PL/ACC-DOX&ICG after NIR irradiation was 93%,which was significantly lower than DOX(65%),PL/ACC-DOX&ICG(65.2%)and PL/ACC-ICG with NIR irradiation(50%).Compared with the PL/ACC-DOX&ICG and PL/ACC-ICG with NIR irradiation groups,the ability of the PL/ACC-DOX&ICG with NIR irradiation group inhibiting cell migration and invasion was significantly improved.PL/ACC-DOX&ICG showed strong tumor-homing property by significant passive accumulation and significant PTT effects with laser irradiation on 4T1 orthotopic mammary tumor metastasis model mice after intravenously injecting.Compared to free ICG,the tumor distribution of PL/ACC-DOX&ICG increased 3.7 times.After 12 h of tail vein administration and near-infrared illumination for 5 min,the temperature of tumor tissue in PL/ACC-DOX&ICG administered group increased rapidly,and the highest temperature reached to 54.5 ?,which was significantly higher than that of free ICG group(44.5 ?)and PBS groups(41.7 ?).PL/ACC-DOX&ICG were capable of delivering DOX from the outside to the inside of the solid tumor and achieving DOX deep penetration into the tumor under NIR irradiation,because collagen with fiber-like structures became completely unstructured and the thickness of stroma was diminished under treatment of PL/ACC-DOX&ICG plus irradiation,which eliminated physical barriers and improved the spread of therapeutic agents throughout the tumor mass.Compared with the negative control group,the tumor growth inhibition rates of DOX,PL/ACC-ICG with NIR irradiation,PL/ACC-DOX&ICG and PL/ACC-DOX&ICG with NIR irradiation were 50.05%,60.08%,67.96%and 94.88%,respectively,and the inhibition rates of lung metastases were 44.4%,54.4%,60.2%,and 93.6%,indicating that hyperthermia combined with chemotherapy significantly improved the efficacy of drug-loaded nanoparticles in inhibiting tumor growth and lung metastasis in model animals.All results indicated that primary tumor growth and lung metastasis in vivo could be primarily inhibited by PL/ACC-DOX&ICG with irradiation,which was likely attributed to remarkable passive accumulation of PL/ACC-DOX&ICG and significant hyperthermia,followed by the hyperthermia-triggered deeper penetration of DOX in the tumor tissues and the hyperthermia-aided functionality of DOX.Therefore,PL/ACC-DOX&ICG could be used as a promising DDSs with tumor-guild drug-release capabilities in future breast cancer treatment.