Research On Nanodrug Delivery System Loaded With DOX In The Treatment Of Gastric Cancer

ObjectiveNanomaterials with photothermal properties were prepared and used as targeted delivery carriers for anti-tumor drugs,so as to study the mechanism of killing tumor in the treatment of gastric cancer.MethodsIn this study,Bi₂Se₃nanomaterials were synthesized by bismuth nitrate,PVP,sodium hydroxide,glucose and sodium selenite as raw materials.The material has low biological toxicity and strong drug loading capacity.Drug-loaded Bi₂Se₃cannot release drugs in the PH environment of normal tissues,but can release drugs in the weakly acidic conditions of tumor microenvironment,thus targeting and killing tumor cells.Targeted delivery system for antitumor drugs.It is mainly divided into three parts:1.Preparation of nanomaterials:Precursor Bi₂O₃build,hydration bismuth nitrate to 5 in the reaction kettle bladder mixed stirring for 10 minutes,anhydrous ethanol and sodium hydroxide,polyvinylpyrrolidone（PVP）after ultrasonic oscillation to drug completely dissolved,import it into the reaction kettle tank,after 10 minutes,stir into the kettle body,cover tightly kettle cover,put into the oven,150℃,reaction 3hours.After the reactor was lowered to room temperature,the products in the liner were poured into the centrifuge tube,centrifuged for 5 minutes at 10000 RPM,then supernatant was removed,ultra-pure water was added,ultrasonic shock dissolved,and centrifuged again.After centrifugation three times,the precipitation obtained is Bi2O3;Bi2Se3 preparation:the ultra-pure water and glucose into the beaker stirring dissolved for 10 minutes,containing Bi2O3 centrifugal tube to add 5ml ultra-pure water,ultrasonic shock to complete dissolution,then drop by drop into the beaker,stirring 10 minutes after the oven,150℃,reaction for 12 hours, centrifugation method with the preparation of Bi2O3;,doxorubicin（Dox）and Bi2Se3 were stirred for 24 hours to avoid light,so that the drug was loaded on the nanomaterial,and finally the nanodrug delivery system loaded Dox was successfully prepared.2.Application of Bi₂SE₃-DOX in the treatment of gastric cancer:conduct cell and long-term in vivo toxicity experiments,cell uptake experiments and in vitro treatment experiments of nanomaterials.2.1 Cytotoxicity test:Different concentrations of Bi₂Se₃ solution were added to mouse gastric cancer fine（MFC）and mouse fibroblast（L929）with exponential growth in 96-well plates.After 24 hours of culture,cytotoxicity was determined by CCK-8 method,and cell survival rate=（OD value of the experimental group/OD value of the control group）×100%.The cytotoxicity of materials was evaluated by cell survival rate.2.2 Long-term in vivo toxicity Test:In order to verify the long-term toxicity of Bi2Se3 in vivo,healthy Balb/C mice were randomly divided into two groups with 6 mice in each group.One group was intravenously injected with 100μL PBS,and the other group was intravenously injected with 100μL Bi₂Se₃ solution at a concentration of 200μg/m L.After 30 days,the eyes of the mice were taken for blood test,and the blood routine,liver function and kidney function were detected to compare whether there was any difference between the two groups and whether there was any statistical difference.At the same time,the main organs of the mice（heart,liver,spleen,lung and kidney）were taken out and made into paraffin sections,and there was no difference between the two groups under microscope.2.3 Cell uptake assay:DOX（20μg/m L）and Bi₂SE₃-DOX（Bi₂Se₃:DOX=62:20μg/m L）solution was added into 24 well plates with exponential growth of mouse gastric cancer cells（MFC）.After one day of culture,DAPI dye was added to fix the cells,and DOX uptake by MFC was observed under fluorescence microscope.2.4 In vitro treatment experiment:The MFC was treated in a 96-well plate with exponential growth of gastric cancer（MFC）in mice by the following groups:（1） Bi2SE3-DOX+NIR（light）（2）DOX（3）Bi2Se3+NIR（light）（4）Bi2Se3-DOX（5） blank control.After cultured for one day,the cell survival rate of each group was determined by the method of determining cytotoxicity.The killing effect of each group on MFC was compared.Result1.Bi₂Se₃nanoparticles have good morphology and size,uniform size and good dispersion,with a diameter of about 50nm and an average hydrated particle size of162.8nm.2.The 808 nm near-infrared laser emitter is set at a certain power,and Bi₂Se₃solution with different concentrations is configured to test its heating effect.It is found that the heating effect is positively correlated with the laser power and solution concentration,and the photothermal performance is stable.3.PH and light will affect the speed and amount of DOX release by Bi₂Se₃-DOX system,while 808 nm near-infrared laser irradiation and acidic environment will promote DOX release.4.Bi₂Se₃has good biocompatibility and no significant toxicity at the cellular and tissue level.5.The efficacy of Bi₂Se₃-DOX+irradiation on mouse gastric cancer cells was better than that of Bi₂Se₃+irradiation and DOX group.Bi2Se3 can promote DOX entry into tumor cells,while Bi₂Se₃-DOX+irradiation can play a synergistic effect of Bi₂Se₃ photothermal therapy and DOX direct killing,and there was a significant differenceconclusionBi₂Se₃nanomaterial has high photothermal conversion rate,good biocompatibility,good photothermal properties,and can act as DOX nanodrug delivery carrier to promote DOX into tumor cells.The nano drug delivery carrier can play a synergistic effect of Bi₂Se₃photothermal therapy and DOX tumor killing,and its therapeutic effect is superior to chemotherapy alone.In addition,the drug delivery system can maintain the effective drug concentration for a longer period of time,thus killing mouse gastric cancer cells more effectively,providing a new direction for optimizing the treatment of gastric cancer.