Research On The In Vivo Distribution Of Covalent Organic Frameworks (COFs) Induced By Chinese Materia Medicas And The Applications Of COFs In Drug Delivery And Intracellular Imaging

Objective:In recent years,Chinese Materia Medicas(CMMs)has shown its unique role in the treatment of cancer due to the therapeutic philosophy of“holistic concept”,“strengthening the body and eliminating the evil”,and following the principle of“dialectical treatment”.It is worth noting that,CMMs for promoting blood circulation and removing stasis plays an important role in the prevention and treatment of cancer.The Chinese medical classic ancient books of“Neijing”recorded the therapeutic concept of“smoothing the blood and regulating the qi”,which provided the theoretical basis for the medical application of CMMs for promoting blood circulation and removing stasis.Studies have shown that CMMs for promoting blood circulation and removing stasis can not only effectively enhance the physiological functions of related tissues and protect them,but also effectively eliminate the accumulation of gall caused by qi and blood disorders and prevent occurrence of tumor.It is of positive significance to the prevention and treatment of cancer.By improving the hemodynamics and hemorheology of related tissues,the CMMs for promoting blood circulation and removing stasis show a specific effect on the blood microcirculation of specific organs such as liver,lung and spleen,and can effectively regulate the blood flow of related organs,which results in enhancing the material exchange between the tissue and the blood.The characteristic of CMMs for promoting blood circulation and removing stasis gives us an important inspiration:if the function of improving the microcirculation of specific organs of CMMs be combined with the potential of modern nanomaterials in the field of tumor treatment,the problem of the lack of tissue specific delivery of nanomaterials itself can be improved.At present,among the drug delivery systems for tumors treatment,nano-drug delivery systems(NDDSs)have shown unique advantages over traditional direct drug delivery system,including controlled release of drug,improved biocompatibility,feasibility of being functionalized and high-efficiency of drug delivery.Among them,Covalent Organic Framework(COFs),due to their unique properties such as large specific surface area,good crystallinity and excellent biocompatibility,display good drug loading capacity and high drug delivery efficiency.COFs show broad application prospects in the field of drug delivery.However,there are still some key issues that need to be resolved in the application of NDDSs in tumor therapy.For example,although a series of important advances have been achieved in targeting specific tumor cells through the functional strategy of NDDSs,there are few reports about the specific accumulation of NDDSs in organs.It is of great significance for improving the overall delivery efficiency of NDDSs in organisms and improving the therapeutic effects of drugs.To solve this problem,researchers turned their attention to the field of CMMs.In-depth research showed that CMMs for promoting blood circulation and removing stasis had specific effects on the blood microcirculation of specific organs such as liver,lung and spleen,etc.,and could effectively regulate the blood microcirculation of related organs.The unique properties of the CMMs for promoting blood circulation and removing stasis can effectively improve the microcirculation of specific organs,increase the blood perfusion volume of this part,which results in increasing the material exchange between organs and blood circulation.This character will help the enrichment of NDDSs at specific sites and provide a new way to achieve organ specific delivery of NDDSs.Based on the above consideration,the objectives of present paper are as follows:Firstly,the research of this thesis focuses on the combined application of CMMs for promoting blood circulation and removing stasis(here Ligusticum chuanxiong Hort)and new nanomaterial COFs in tumor treatment.The tissue distribution of COF-HQ in mice were explored induced by Ligusticum chuanxiong Hort,which has the effect of promoting blood circulation and removing stasis,to verify the ability of Ligusticum chuanxiong Hort in inducing the selective accumulation of COF-HQ in specific organs.Secondly,we further studied the ability of COF-HQ as a drug carrier to achieve high-efficiency drug delivery.Thirdly,the potential of the methoxy functionalized covalent organic framework TAPB-DMTP-COF in application of bioimaging was explored.In the last,we further explored the enhancement of tumor cell suppression ability of TAPB-DMTP-COF drug delivery system through rich functionalization.This series of studies provided constructive ideas for increasing the specific aggregation of COFs at the lesion site,improving the efficiency of drug delivery,and improving the therapeutic efficiency by combination of CMMs and NDDSs.Methods:1.Characterizations of COFs:Used scan electric microscope(SEM),transmission electric microscope(TEM),Fourier transform infrared spectrometer(FT-IR),fluorescence spectrophotometer,powder X-ray diffraction(PXRD)and N₂ adsorption and desorption experiments to characterize the structure and properties of COFs.2.Drug loading and release:UV-Vis spectrophotometer(UV-Vis)was used to monitor drug loading and release.3.Cell experiments:B16F10 and 4T1 cells were used in cytotoxicity assays,cell uptake and intracellular fluorescence imaging.Confocal laser microscope(CLSM)and inverted fluorescence microscope were used to observe cell uptake and intracellular fluorescence imaging.4.Animal experiments:COF-HQ in vivo distribution and the in vivo anti-tumor effect evaluation of COF-HQ drug delivery system were performed using C57BL/6 mice as model.Inductively coupled plasma mass spectrometry(ICP-MS)was used to detect the tissue distribution of COF-HQ.The in vivo anti-tumor effect evaluation of TAPB-DMTP-COF drug delivery system were performed using BALB/c mice as model.Hematoxylin-eosin staining(H&E staining)was used to observe the tissue morphology.Results:1.Ligusticum chuanxiong Hort could effectively induce the specific accumulation of COF-HQ in liver and spleen,and COF-HQ nanoparticles showed a certain degree of organ-specific distribution during the circulation process in mice.2.The COF-HQ drug-loading system constructed with 5-fluorouracil(5-FU)as a model molecule achieved higher drug-loading capacity.Due to its p H-sensitive drug release capability and good biocompatibility,the5-FU@COF-HQ system exhibited highly effective tumor suppression capabilities.3.The fluorescence intensity of TAPB-DMTP-COF showed p H-sensitive,which resulted in a p H-dependent intracellular fluorescence imaging.The TAPB-DMTP-COF could be applied to fluorescence imaging of low p H areas inside tumor cells.4.TAPB-DMTP-COF was loaded with camptothecin(CPT)and amphiphilic lipid-modified doxorubicin(amph-DOX-Lipid)to construct a dual drug delivery system with p H-sensitive drug release behavior and mitochondrial targeting ability.The constructed dual-drug-loaded NDDS effectively increased the level of intracellular reactive oxygen species(ROS)near mitochondria and achieve efficient tumor cell suppression based on the mitochondrial pathway.Conclusions:The results of the thesis confirmed that the CMMs for promoting blood circulation and removing stasis can effectively induce the specific accumulation of COFs in specific organs,achieving the organ specific aggregation of COFs.This study initially explored and achieve organs-specific drug delivery through the combination of Chinese and Western medicine and provided new ideas for improving drug delivery efficiency and enhancing the therapeutic effect.Furthermore,high-efficiency mitochondrial targeting drug delivery and bioimage in cell were achieved through functionalization of COFs.The present work integrated the advantages of CMMs and NDDS(COFs),which further expanded the application of CMMs as organ specific inducing and COFs as drug carriers in the field of cancer treatment.