Constructions Of Boron Nitride Nanoplatforms For Anticancer Applications

Cancer is one of the main factors that endanger human life and health.It refers to a disease in which normal cells are stimulated by carcinogen,leading to abnormal proliferation and differentiation of cells,and finally developing into tumor tissues.However,breast cancer is characterized by rapid growth,easy metastasis and recurrence,and generation of drug resistance after therapies,making the eradication of the tumor cells and complete rehabilitation very challenging.According to the report of the World Health Organization,breast cancer has become the most common cancer in the world.Overcoming cancer is an important issue related to the future of mankind.Traditional solutions,such as surgery,chemotherapy and radiotherapy,have been applied in clinical practice,but there are some shortcomings,such as difficult eradication,great side effects and low selectivity.Therefore,emerging therapeutic strategies such as photothermal therapy,photodynamic therapy,and self-therapy have attracted more and more attention.Photothermal therapy(PTT)and photodynamic therapy(PDT)are therapeutic methods that absorb light energy into heat or transfer energy to produce reactive oxygen species(ROS),which destroy the function of cancer cells and lead to their apoptosis and necrosis.Self-therapy can produce ROS or release drugs in vivo to achieve therapeutic effects without external stimuli.Boron nitride(BN)nanomaterials have outstanding oxidation resistance,thermal stability and chemical stability,as well as various nanostructures such as nanosheets,nanotubes and nanospheres.In recent years,BN nanomaterials have opened up a new way in biomedical field,which can be used for drug delivery,boron neutron therapy and boron release self-therapy.However,clinical practice and exploratory research show that single treatment has limited effect and can not eliminate tumor completely.Multimodel therapy is the trend of future research.Boron nitride,as a kind of nanomaterial with good biocompatibility,has great potential in future multifunctional cancer diagnosis and treatment.In this thesis,we designed and prepared nanomaterials based on boron nitride and studied their potential applications in anti-tumor.The main content is as follows.Based on boron nitride nanospheres,a new artificial nanoenzyme BON was developed,and its chemical composition and internal bonding were systematically studied.Fluorescence probe was used to evaluate the nanoenzyme characteristics of BON catalyzing hydrogen peroxide to produce hydroxyl radicals in vitro and in vivo.Co-localization results showed that BON accumulated in lysosomes.And cytotoxicity experiments showed that BON induced apoptosis and necrosis by producing hydroxyl radical and releasing boron.The animal tumor model was constructed,and it was found that the tumor inhibition rate of BON was as high as 97%.Degradation experiment showed that BON had good biological safety,which confirmed the application potential of BON in anti-cancers.Using boron source,nitrogen source and carbon source as precursor,spherical nanomaterial BCN with strong absorption for near infrared light was prepared.Under the irradiation of 808nm laser,the temperature of the system increased by 26 degrees within 10 minutes,and the photo-thermal stability was good.In addition,ROS detection shows that BCN can produce superoxide anion in cells stimulated by laser.Cytotoxicity experiment show that BCN can significantly kill cancer cells by photothermal effect and photodynamic effect.BNMS with boric acid and guanidine carbonate as precursors were prepared at different proportions and synthesis temperatures.The effects of the above factors on the physical and chemical structure of the materials were clarified by systematic characterization.The results show that with the increase of preparation temperature,the crystallinity of porous boron nitride increases and the pore structure changes significantly.BET results show that when the reaction temperature is 1100℃,the maximum specific surface area of the material can reach 1080 m~2/g,and the total pore volume is 1.01 cm~3/g.The rich mesoporous structure and high specific surface area of BNMS have great advantages for drug loading.