Multi-responsive Nano Graphene Oxide Loaded With PEGylated Doxorubicin Nanodrugs For Chemo-Photothermal Therapy

DOX is a broad-spectrum antitumor drug,against a wide range of cancers.However,it can cause severe adverse sides.To increase the therapeutic effect of DOX and to attenuate it’s toxicity effect toward normal tissues,in this study,we successfully prepared multi-responsive three kinds of NGO@DOX-PEG nanodrugs(namely NGO@DOX-PEG2 K,NGO@DOX-PEG5 K and NGO@DOX-PEG20K),which had good solubility,multiple responsive drug release,long circulation in blood.And chemo-photothermal therapy was carried out using the photothermal conversion capability of the carrier nano graphene oxide(NGO).The main work were as follows:The first part described the preparation and characterization.Firstly,PEG-COOH was conjugated with DOX via amido bond and obtained three kinds of DOX-PEG polymers(namely DOX-PEG2 K,DOX-PEG5 K and DOX-PEG20K).And then,NGO was used as the carrier for anticancer drug DOX and polyethylene glycol-functionalized doxorubicin(DOX-PEG)by π–π stacking and hydrogen bonding,which resulted in NGO/DOX and three hydrophilic nanodrugs of NGO@DOX-PEG2 K,NGO@DOX-PEG5 K and NGO@DOX-PEG20 K.Ultraviolet visible(UV-Vis),Fourier transformed infrared(FTIR)and fluorescent spectrum suggested the NGO@DOX-PEG nanodrugs were successfully prepared.Photothermal effect of nanodrugs showed NGO@DOX-PEG could absorb the incoming NIR light and convert the photon energy into heat.Drug release revealed the behavior of DOX was released from NGO@DOX-PEG nanodrugs was multi-responsive(pH sensitive and NIR initiated),and the drug release of NGO@DOX-PEG5 K nanodrug was the best.Therefore,NGO@DOX-PEG nanodrugs might have potential chemo-photothermal ability.In the second part,cytotoxicity evaluation was performed.Firstly,we verified the carrier NGO was non-toxic in human cervical cancer Hela cells by MTT,suggesting it has a high security.In vitro cytotoxicity of NGO@DOX-PEG nanodrugs against Hela cells with or without NIR laser,and free DOX and NGO/DOX were as control group.The results indicted the cytotoxicity of NGO@DOX-PEG nanodrugs was lower than free DOX,while higher than NGO/DOX when no NIR laser irradiation.When with NIR laser irradiation,cytotoxicity of NGO@DOX-PEG nanodrugs was significantly enhanced and was equivalent to free DOX,while free DOX against Hela cells hasn’t obvious change compared to no NIR laser.That was to say NIR irradiation enhanced the cytotoxicity of NGO@DOX-PEG nanodrugs.In vitro cellular internalization suggested the cellular uptake of all nanodrugs was in a time-dependent manner,and the cellular uptake of NGO@DOX-PEG5 K was better than another four.Confocal laser scanning microscope(CLSM)suggested NGO@DOX-PEG nanodrugs released drugs slowly into the nucleus.And NGO@DOX-PEG5 K was best nanodrug among nanodrugs for antitumor in vitro.Furthermore,endocytic pathways including clathrin-mediated endocytosis and macropinocytosis-dependent endocytosis were involved,and clathrin-mediated endocytosis was the main form in the internalization of NGO@DOX-PEG nanodrugs to Hela cells.In the third part,we verified the biodistribution of NGO@DOX-PEG5 K,which was the best nanodrug against Hela in vitro,and free DOX in the normal tissue and tumor in a xenograft model in nude mice in vivo.Compared with free DOX,NGO@DOX-PEG5 K afforded much higher antitumor efficacy may due to longer circulation time,and without obvious toxic effect to normal organs.Taken together,NGO@DOX-PEG5 K possessed the great superiorities including nice stability,slow release capability,efficient photothermal effect and long blood circulation capability,so NGO@DOX-PEG5 K has tumor passive targeting,which indicated that it has better tumor treatment effect.