Study On The Bioavailability And Mechanism Of Oral Delivery Of CMC/PLGA/DOX NPs

Background Cancer is a serious hazard to human health,and it is still a difficult medical problem.The interaction between the tumor microenvironment(TME)and tumor cells plays a vital role in the occurrence,growth and metastasis of tumors.The high permeability and retention effect(EPR effect)of solid tumors based on the tumor microenvironment provide a new strategy for targeted therapy of tumors.At present,the clinical treatment of cancer is mainly through surgical removal,chemical drug treatment and radiotherapy.And one of the most commonly used treatments is that most of the chemical drugs used in the treatment of chemical drugs are injections,such as cyclophosphamide,docetaxel,and doxorubicin hydrochloride.However,the use of injections also brings a series of side effects: 1.The intravenous injection process will cause the drug to reach a dose that exceeds the maximum tolerable concentration in the patient’s body within a short time,causing serious harm to the body,and then It is rapidly metabolized in the circulatory system of the body;2.In order to enhance the solubility of the injection of the drug,it is usually necessary to add different co-solvents before administration,and most of the co-solvents can also lead to the occurrence of adverse reactions such as allergies.Compared with intravenous administration,oral chemotherapy has obvious advantages: 1.The effective drug concentration in the systemic circulation can be maintained during the drug administration,thereby enhancing the efficacy;2.The oral administration of the drug effectively avoids the side effects caused by the cosolvent,And reduces the pain of patients during treatment,and does not require hospitalization,so oral chemotherapy has higher patient compliance and improves the quality of life of patients.However,there are still some problems that need to be solved urgently for oral chemotherapy: 1.Most anti-cancer drugs have poor hydrophilicity and usually pass through the gastrointestinal tract(GI)during oral administration,resulting in the stability of the drug Sexuality is reduced,thereby reducing the bioavailability of the drug;2.Some studies on different hydrophobic anticancer drugs have shown that most anticancer drugs cannot be directly absorbed by the oral chemotherapy route,and only a few drugs can enter the systemic circulation to play a role.Experimental purpose Based on the theory of TME and EPR effects,and combined with modern nano delivery technology,we propose to load doxorubicin(DOX)into Carboxymethyl chitosan(CMC)and poly(lactide-co-glycolide)(PLGA)to become CMC/PLGA/DOX NPs and use it in the oral delivery of nano drugs.We hope that this oral nano delivery strategy can improve the scientific research hypothesis of anti-cancer effect,investigate its physical and chemical properties and in vitro release characteristics,and study the promotion of DOX intestinal absorption by the nanoparticles And clarify its mechanism.Experimental method 1.Preparation and characterization We have successfully prepared CMC/PLGA/DOX NPs using the emulsificationsolvent volatilization method.At the same time,we have performed physical and chemical characterization tests on the prepared nanoparticles.The surface morphology and dispersion of the nanoparticles were observed by transmission electron microscopy.Zeta PALS high resolution potential and particle size analyzer were used to detect the orientation and surface particle size of the nanoparticles.The preparation stability of the nanoparticles was analyzed by differential scanning calorimetry and tested.Fourier transform infrared spectroscopy(FTIR)and X ray diffraction(XRD)were used to detect whether the free drug was successfully contained in the nanoparticles.Fluorescence spectrophotometer was used to detect the loading rate and drug loading rate of the nanoparticles,as well as the p H-sensitive release in vitro.2.Study on drug uptake and absorption inhibitors of Caco-2 cells The study of Caco-2 intracellular drug uptake and inhibitor experiments explored the effect of CMC/PLGA NPs on oral absorption of DOX and its possible mechanism;the CCK-8 method was used to study the cytotoxicity of CMC/PLGA NPs.3.Pharmacokinetics The pharmacokinetics of DOX intravenous injection,oral replacement of DOX,and oral replacement of CMC/PLGA/DOX NPs were studied in rats using the microplate method.Result 1.Physical and chemical characterization of nanoparticles The average size of the nanoparticles prepared by us is 100-200 nm,which is expected to be uniform and well dispersed.Since the surface of the nanoparticles has negative nanoparticles,no aggregation occurs.Differential scanning calorimetry,Fourier infrared and X ray fluorescence spectrophotometers have detected that CMC/ PLGA/DOX NPs have high encapsulation and drug loading rates,which can meet the requirements of subsequent experiments in this study.Volume,CMC/PLGA/DOX NPs can maintain stability under gastric acid environment and can respond to different p H to achieve controlled release of drugs.2.Study on drug uptake and absorption inhibitors of Caco-2 cells Caco-2 intracellular drug uptake studies have shown that CMC/PLGA/DOX NPs are effectively absorbed within 1 h-4 h,and inhibitor studies have shown that the mechanism of entry of CMC/PLGA/DOX NPs into the cell is mainly mediated by clathrin.Cytotoxicity test results show that CMC/PLGA NPs are a non-toxic drug delivery vehicle.3.Pharmacokinetics Pharmacokinetic studies show that CMC/PLGA/DOX NPs can significantly prolong the circulation time of DOX at 24 h,avoid rapid drug metabolism,and avoid damage to the body caused by drugs exceeding the maximum tolerated concentration.Conclusion In this study,we designed and prepared an oral replacement nanoparticle: CMC/PLGA/DOX NPs.The oral delivery nanoparticles can be stable in a molten channel environment and have different p H responsiveness.Transporting nanoparticles through clathrin-mediated endocytosis can effectively improve the bioavailability of DOX in vivo.