Study On The Synthesis Of Fluorescent Covalent Organic Framework Materials And Their Drug Loading Properties

Covalent organic frameworks(COFs)are porous framework materials with periodic structure formed through covalent bonds by connecting light elements C,O,N,B,H,and Si,etc.COFs,as a new type of porous material,have the advantages of low density,controllable pore structure,large specific surface area,and stable existence in organic solvents and thermal environments.And they are showing great application potential in many fields,such as gas absorption,energy storage,catalyst,membrane separation and photoelectrochemistry.However,their application in biomedicine is still a huge challenge due to the harsh synthetic conditions and relatively large size.In this study,we explored a mild solvothermal method to synthesize COFs with nanostructures and bright fluorescence.The new COFs not only achieved to monitor drug loading process by naked eyes for the first time,but also showed high drug loading capacity and pH-responsive release performance.In order to enhance the fluorescence performance of COFs,this study developed a simple and effective synthesis strategy.For the first time,pre-conjugated monomers of tri-(4-formylphenyl)amine were used to construct the strongly conjugated COFs material.Through research on the structure,morphology,and fluorescence properties,it was proven that COFs had a smaller size,high surface area,and bright blue fluorescence.In addition,an effective anti-cancer drug of doxorubicin(DOX)was loaded via π-π conjugate interactions to construct an effective fluorescence resonance energy transfer system,which finally resulted into a novel visual drug loading pattern without using common analytical equipment.On this basis,this study also carried out the research on drug loading and in vitro drug release behavior of COFs under different pH conditions.Through systematic research on the cytotoxicity of COFs and the therapeutic effect after loading drugs,it was found that COFs itself had relatively low cytotoxicity,and compared with single chemotherapy,COFs+DOX were easily taken up into cells by endocytosis.It exhibited continuous drug release property under weakly acidic conditions in cancer cells,and significantly improved the therapeutic effect.In particular,due to the special fluorescence property,a significant fluorescence quenching system was built after DOX being loaded onto COFs,and the drug was released responsively under acidic conditions after entering the cell,providing visual monitor and observation of drug loading and tracking of drug release.Preventing cancer cell migration significantly enhanced the therapeutic effect,and simultaneously reduced damage to normal cells.At present,there are few studies on the anti-migration study of COFs,and thus the anti-migration mechanism is still unclear.Therefore,this study also conducted experimental studies on the anti-migration of cancer cells treated by COFs+DOX.The experimental results showed COFs+DOX group had significant inhibitory effects on the migration of cancer cells,while COFs or DOX alone had little effect.Considering the mild and simple synthesis methods,unique structures,special fluorescent properties,good biocompatibility and therapeutic effects of COFs,this study may have potential research value and application prospects in the fields of chemistry,materials science and biomedicine.