Research On Controlled Release Properties And Tumor Therapy Of Multifunctional Response Composites

In recent years,the multifunctionally controlled drug release system has attracted widespread attention because of its high sensitivity,specificity,strong therapeutic effect,low toxic,and side effects.As a controlled drug release system,it can achieve the effect of killing tumor cells by relaese the guest molecules loaded in the carrior after various external stimuli,such as sound,light,p H,temperature,magnetic field,electric field,etc.Based on the advantages of the above multifunctional response carriors,this dissertation uses hollow mesoporous silica and chitosan-carboxymethylcellulose nanohydrogel as carriors to prepare electric field-responsive controlled-release drug carriors,and studies their physical properties,controlled release performance,cell phagocytosis,biological safety,and tumor killing performance,then the results yielded as follow:（1）HMSN-CC-EDTA-Gox-Cu²⁺functional carrior was prepared as follows.Hollow mesoporous silica nanoparticles（HMSN）are prepared and coated with a chitosan-carboxymethyl cellulose polymer layer（CS-CMC）that can respond to an electric field.The carrior was used to adsorb the chelating agent ethylenediaminetetraacetic acid（EDTA）and fix the EDTA inside the carrior.After the carrior was washed,glucose oxidase（Gox）inhibited by copper ions was immobilized on the polymer layer to prepare the electric field-response drug controlled-release carrior(HMSN-CC-EDTA-Gox-Cu²⁺).Under the stimulation of an electric field,the loaded EDTA can be released from the inside of the carrior,and the released EDTA can chelate copper ions,so that the activity of Gox inhibited by copper ions on the sample surface is restored,and then the glucose in the cells is catalyzed to produce H₂O₂.Copper ions can also further catalyze H₂O₂ to produce·OH to kill tumor cells.The level of ROS was improved as proved by the increased fluorescence intensity of the prepared carrior after electric field stimulation.It was further proved that the HMSN-CC-EDTA-Gox-Cu²⁺nanocarrior can produce·OH after electric field stimulation,as prove by the adsorption at a wavelength of 652 nm of the oxidized TMB by·OH.Using mouse breast tumor 4T1 cells as a tumor cell model,in vitro experiments were carried out concerning biological safety,cell killing,phagocytosis,and intracellular reactive oxygen species（ROS）of the prepared electric field-response controlled-release carrior.The functional carrior has good biological safety.The number of tumor cells is significantly decreased after functional carrior and electric field added.The photos of cell phagocytosis prove that the functional carrior can be swallowed by tumor cells and around the nucleus.The ROS experiment proves that the functional carrior with an electric field can generate ROS in the tumor cells.It can be concluded that the functional carrior can generate ROS after electric field stimulation,thereby killing Tumor cells.（2）Electric field and ultrasonic response HMSN-CC-Catechol-Ca O₂-Fe₂O₃-Gox nanoparticles was prepared as follows.Hollow mesoporous silica nanoparticles（HMSN）were prepared and coated with a chitosan-carboxymethyl cellulose polymer layer（CS-CMC）that can respond to an electric field.The dipoles catechol were grafted on CS-CMC.Calcium peroxide（Ca O₂）and Iron oxide（Fe₂O₃）were synthesized in situ inside the carrior,and glucose oxidase（Gox）was loaded to prepare electric field and ultrasonic response HMSN-CC-Catechol-Ca O₂-Fe₂O₃-Gox nanoparticles.The stimulation of the electric field makes nanoparticles release Ca O₂and Fe₂O₃ more quickly,and generate more ROS.When the guest is released,the nanoparticles return to the hollow mesoporous structure,and ultrasonic cavitation is enhanced under the ultrasound.Ultrasonic cavitation can generate more ROS and achieve a stronger effect of killing tumor cells.The experimental results show that both electric field and ultrasonic stimulation can make the nanoparticles generate more ROS than the control group.The reaction mechanism is as follows:Ca O₂ was decomposed to ROS and O₂ under the ultrasound.The generarted O₂ reacts with glucose under the catalysis of Gox to generate hydrogen peroxide.The ROS,singlet oxygen and oxygen are produced by Fenton reaction of hydrogen peroxide catalyzed by iron oxide.The reaction is repeated to produce more ROS.Cell experiments showed that HMSN-CC-Catechol-Ca O₂-Fe₂O₃-Gox nanoparticles alone showed low cytotoxicity and could be swallowed by tumor cells.When it was stimulated by electric field and ultrasound,it showed high killing ability to tumor cells.Animal experiments showed that the nanoparticles have no toxic and side effects on mice at a concentration of 20 mg/kg,and can have strong inhibitory and killing effects on mouse 4T1 tumor tissue under electric field and ultrasonic stimulation.