Application Of Nano-Covalent Organic Frameworks (Cofs) In Tumor Phototherapy

Cancer is one of the major diseases threatening human health.In the process of continuous exploration of cancer diagnosis and treatment,nanomedicine is regarded as a more promising field.The rapid development of nanomaterials and nanotechnology provides effective therapeutic approaches for cancer treatment.Therefore,it is crucial to find nanomaterials that can improve therapeutic efficacy and safety.Nanoscale covalent organic frameworks（NCOFs）have attracted great interest due to their excellent drug loading capacity,high drug delivery efficiency,and excellent stability,and have been widely used in biomedical fields.In terms of high reactive oxygen species generation and high photothermal conversion capacity,covalent organic frameworks have broad designability and functionality,opening a new avenue for cancer therapy.Photodynamic therapy（PDT）and photothermal therapy（PTT）are the two main types of light therapy.PDT utilizes photosensitizer（PS）to generate reactive oxygen species（ROS）under light to kill tumor cells,while PTT kills tumors by local hyperthermia induced by photothermal agent（PTA）under light.Multifunctional nanoparticles can serve as nanotherapeutic platforms for PDT and PTT.At the same time,based on the drug delivery properties of nanoparticles,emerging nanomaterials can be combined with traditional chemotherapeutic drugs to overcome the shortcomings of traditional therapies and provide new possibilities for optimizing cancer treatment.However,these high-performance nanoplatform-based anticancer treatments remain challenging due to the complex tumor microenvironment（TME）and induced therapeutic resistance.In this thesis,two examples of composite nanomaterials with efficient phototherapeutic properties were designed and synthesized using NCOFs as carriers,and their anticancer activities were investigated.The first chapter mainly introduces the applications and challenges of nanomaterials in cancer therapy;the structure and characteristics of COFs;the synthesis of NCOFs;the functionalization of NCOFs and the application of NCOFs in cancer therapy.In the second chapter,Pt@COF-BDP nanomaterials are mainly synthesized.Photodynamic therapy is widely used as a non-invasive cancer treatment method.Pt@COF-BDP nanomaterials introduce the photosensitizer BODIPY into the nanoplatform for Photodynamic therapy.A hypoxic microenvironment is a typical feature of solid tumors.Due to the influence of TME,the effect of photodynamic therapy is greatly reduced,so we introduced Pt nanozyme,which can decompose the endogenous H₂O₂of tumor into O₂,which will effectively alleviate the limitation of hypoxia on the effect of photodynamic therapy and improve treatment effect.In the third chapter,the Pd@COF/H₂nanomaterials were mainly synthesized.Hydrogen gas is considered as a safe therapeutic agent and has been widely used in tumor therapy since its antitumor effect was discovered.Pd nanoparticles can adsorb hydrogen for hydrogen therapy,and Pd@COF/H₂has a good photothermal effect under near-infrared light irradiation,and the increase of temperature can also promote the release of hydrogen.Therefore,Pd@COF/H₂nanomaterials combine photothermal therapy and hydrogen therapy to treat cancer and achieve good therapeutic effects.The excellent drug loading capacity and high drug delivery efficiency and excellent stability of NCOFs are very beneficial for realizing biomedical applications in vivo.Although COF-based therapeutic systems are still in their infancy,their unique properties and potential applications in oncology have inspired more and more researchers to work on this promising field.However,the current challenges and limitations of COFs cannot be ignored.