| Malignant tumors are one of the important factors that threaten people’s health today.Chemotherapy has become the main way to treat cancer in clinical practice.However,due to the relatively large side effects of chemotherapy drugs,it is difficult to achieve targeted therapy in the body,resulting in poor therapeutic effects.Limits the clinical application of chemotherapeutics.In recent years,targeted nano-drug delivery systems have become a hot research point,which has improved the toxicity of drugs in vivo to a certain extent and improved the targeted therapeutic effects of drugs.New solutions have been further proposed.Among them,the more effective method is in nano-carriers.A "control gate" is installed on the surface to enable the drug to be released on demand in a specific microenvironment.These drug delivery systems may involve different"control gates" in response to the microenvironment,such as dendrimers,aptamers,antibodies,proteins,peptides,and sugars.The purpose of designing the "control gate"is to load the drug into the nanocarrier and then be triggered by a series of internal and external stimuli(light,ultrasound,pH,temperature,redox substances,enzymes,etc.).Inspired by the above research,this paper introduces disulfide bonds into the carrier through a simple one-pot synthesis method,which responds to the higher concentration of GSH in the cell,forcing the carrier to cleavage and degrade,and accelerate the release of the drug;in addition,because of the inherent biological phase of BSA Capacitive and low-cost,it becomes one of the suitable "controllers".More importantly,it contains abundant amino and carboxyl groups.Under acidic conditions,its structure and potential change potentially,making BSA appear physiological in the blood circulation.Stable;Based on the above characteristics of BSA,this article uses a simple amidation process to couple BSA to the nano-drug delivery system;and due to the high expression of folate receptors on the surface of tumor cells,folic acid is finally modified on the surface of nanospheres to realize nanospheres Actively target tumor tissues to improve the therapeutic effect of the nano drug delivery system.This GSH-triggered biodegradable nanocapsule,with its high specific surface area and large pore size,can effectively load doxorubicin drugs into the silica cavity.Under the condition of high concentration of GSH,it can significantly increase the silica skeleton.The degradation rate of the drug can also accelerate the release of the drug doxorubicin;then the "control gate"-BSA-FA is combined with the nanocapsule through the amide bond,which can prevent the premature release of the drug and achieve the purpose of targeted drug release.In order to construct such a FA-BSA gated nano-drug carrier system,the main research contents of this paper are as follows:Part 1:Preparation and characterization of HMSNs/DOX@BSA-FAThe nanocapsules are synthesized by a simple one-pot synthesis method,adjusting the appropriate ratio of TEOS and BTEPTS-4S,and introducing a sesquioxane skeleton with disulfide bonds;the elemental map analysis shows that the sulfur content is 4%,which is the research method for nano-particles.Redox response degradation provides the basis;the formation of nanospheres with shell-core structure and rough surface,N2 adsorption and desorption curves and pore size distribution prove the existence of hollow mesopores;transmission electron microscopy results show that the average particle size is about 150nm,and nanometer The spheres are relatively stable and have good dispersion;the amino groups are modified on the surface of the nanocarrier by coupling the silanol on the surface of the nanoparticles and the ammoniating reagent(APTES);the DOX is sealed into the hollow mesopores by physical stirring,and the drug loading rate is as high as 30%;BSA combines with the amino groups on the surface of the nanocarrier through the amide reaction to achieve the effect of "control gate";at the same time,BSA-conjugated folic acid actively targets tumor cells.This article also investigates the surface modification of the preparation through potential analysis;UV spectrum and infrared spectrum to further evaluate the surface functionalization of nanomaterials;thermogravimetric analysis diagram determines the grafting rate of the reactants at each step,that is,HMSNs,HMSNs,The weight loss of HMSNs-NH2 and HMSNs@BSA-FA were 79.6%,75.35%,and 63.76%,respectively.The grafting rate of amino group was 4.25%and that of BSA-FA was 11.59%.Finally,under the conditions of simulating the intracellular environment in vitro,the nanopreparation can release the drug responsively,with a release rate of more than 70%,indicating the successful preparation of nanoparticles.Part 2:Study on the in vitro anti-tumor activity of HMSNs/DOX@BSA-FAUsing mouse breast cancer(4T1)as a model cell,the in vitro anti-tumor activity of HMSNs/DOX@BSA-FA was investigated.First,fluorescence microscope and flow cytometry were used to investigate the uptake of doxorubicin-loaded HMSNs/DOX@BSA-FA nanoparticles by 4T1 cells from both qualitatively and quantitatively.From the results,the uptake rate reached more than 95%after 4 hours of incubation,which mainly showed that the active targeting effect of FA allowed the nanospheres to enter tumor cells,proving its excellent targeting.Then,the MTT method was used to investigate the effect of each experimental group on 4T1 cells.Proliferation inhibitory effect,MTT experiment showed that the biosafety of nanocarriers,and compared with free DOX,the preparation group showed higher inhibitory effect as the concentration increased from 0.25 μg to 50μg compared with free DOX,confirming the effectiveness of the preparation Effective delivery;Finally,the preparations were analyzed from the experiments of apoptosis,live death staining and intracellular GSH content determination.The experimental results of apoptosis and cell death staining and intracellular GSH content determination further proved that the preparation group can perform well Its anti-tumor effect,and reduces the level of intracellular GSH.In short,the above experiments have verified the good in vitro anti-tumor activity and targeting ability of this nano-drug delivery system.Part 3:Study on the anti-tumor activity of HMSNs/DOX@BSA-FA in vivoBALB/c tumor-bearing mice were selected as model animal mice to evaluate the antitumor activity of the nano-preparation in vivo.Use small animal live imaging to investigate the distribution of HMSNs/IR783@BSA-FA in tumor-bearing mice,record the fluorescence imaging effect of HMSNs/IR783@BSA-FA in mice,and investigate the fluorescence distribution of isolated organs after 12 hours It was found that the final formulation stayed longer in each tissue than the free IR783,and the results showed that the formulation could be enriched and retained at the tumor site.After intravenous administration to mice,the tumor volume,tumor weight and other indicators showed that HMSNs/DOX@BSA-FA had obvious tumor suppressive effects.The pathological results further proved that the preparation group enhanced the anti-tumor effect and reduced the toxic and side effects of DOX on the main organs. |
PDF Full Text Request