Design Of Black Phosphorus-Based Composites And Their Synergistic Inhibitory Effect And Mechanism On Breast Cancer

Breast cancer is the most common malignant tumor in women,and its main therapeutic strategies include surgical resection,radiotherapy,chemotherapy,endocrine therapy or immunotherapy.On one hand,long-term drug resistance and low targeting of triple negative breast cancer are the challenges of treating breast cancer at present.On the other hand,the side effects caused by drug therapy cannot be ignored.With the development of materials science and nanotechnology,various rising therapeutic methods provide new ideas for tumor treatment.As a two-dimensional material,black phosphorus has good properties of biodegradability,low toxicity of degradation products,photothermal conversion and electron transfer,which makes it a research hotspot in the field of tumor treatment.However,as far as intravenous injection of black phosphorus materials,it is necessary to reduce the potential biosafety risks,and then improve the therapeutic effect of black phosphorus-mediated nano-drugs through postmodification,and finally solve the challenges faced by breast cancer treatment.Therefore,it is an important choice to construct biodegradable black phosphorus-based composites,systematically explore the potential safety risks of the materials,and enhance the growth inhibition of breast cancer through synergistic therapeutic strategies.In this paper,black phosphorus materials with various sizes were obtained by ultrasonic-assisted exfoliation and post-modification of polyethylene glycol,and it was found that the biological safety of black phosphorus materials had obvious size and dosage dependence.Subsequently,the endocrine therapy drugs tamoxifen and folic acid motif were integrated into black phosphorus nanosheets by electrostatic adsorption.It was found that the recognition of folic acid receptor on the surface of drug-resistant breast cancer cells increased the intake of nano-drugs,improved the efficacy of endocrine drugs,and inhibited the growth of drug-resistant breast cancer in cooperation with sonodynamic therapy.Secondly,for triple-negative breast cancer,through the deposition of gold nanoparticles,the ultrasonic process inhibited the surface electron reconstruction of black phosphorus,increased the amount of reactive oxygen species mediated by ultrasound,and thus achieved the growth inhibition effect on triplenegative breast cancer in cooperation with photothermal.Finally,in combination with heme from biological sources,it maked up for the oxygen dependence of photodynamic therapy mediated by black phosphorus,enhanced the therapeutic effect of photodynamic therapy through glutathione consumption,and finally improved the growth inhibition of triple negative breast cancer.The specific research work is mainly as follows:1.In order to study the biological safety risk of black phosphorus materials,black phosphorus materials with different sizes were prepared through ultrasonic-assisted exfoliation and gradient centrifugation.It was found that black phosphorus material with the smaller size beared surface cavitation,fibrosis and crushing,and finally oxidative degradation.The results showed that normal cytotoxicity was closely related to incubation time,black phosphorus concentration and size,and cell types.In addition,after intravenous injection,the size and dosage of black phosphorus material did not affect the number of red blood cells and their related indexes,did not affect the proportion of lymphocytes,and cannot cause inflammatory effect in vivo.In contrast,the changes in the number of white blood cells and the proportion of neutrophils were significantly dependent on the injection dosage and size of black phosphorus materials.At the injection dosage of 2-5 mg kg-1,small and medium-sized black phosphorus materials significantly increased the number of white blood cells and the proportion of neutrophils in the short term,mainly attributing to the high intake speed and intake of small and medium-sized black phosphorus materials;At the injection dosage of 10 mg kg-1,the number of white blood cells and the proportion of neutrophils changed irregularly,indicating that the dosage would increase the biosafety risk of materials.In addition,the study of tissue safety found that the injection dosage of 2-5 mg kg-1 would not cause tissue necrosis,and the effect of black phosphorus with the small size on DNA damage and repair of liver and kidney tissue was less than those of the other two black phosphorus materials.At the injection dosage of 10 mg kg-1,all three black phosphorus materials caused some tissue damage of liver and kidney.In conclusion,the potential safety risks in vivo are closely related to the size,injection dosage and administration mode of black phosphorus material.This part of the study provides the important reference for the animal model and clinical pre-test of black phosphorus material.2.Taking the over-expression of folate receptor on the surface of breast cancer cells as the target,the folate motif modified on the surface of-black phosphorus can conjugate to the folate receptor on the surface of breast cancer cells.Co-incubated with breast cancer cells,nano-drugs promoted the expression of apoptosis protein,reduced the expression of anti-apoptosis protein and related cell cycle genes,and induced more cell apoptosis.Synergistic sonodynamic-endocrine therapy caused the death of drugresistant breast cancer cells in many ways.Through the nude mouse model of drugresistant breast cancer,the corresponding time of the maximum accumulation of nanodrugs in tumor site was determined.Finally,combined with synergistic therapy,nanodrugs have achieved the growth inhibition effect on drug-resistant breast cancer.In addition,during the whole treatment process,the designed nano-materials did not cause serious tissue damage and blood safety risks.This part of the study solved the drug resistance challenge by long-term use of estrogen receptor overexpression breast cancer and side effects caused,and improved the curative effect on this breast cancer.3.In order to overcome the challenge of electronic reconstruction of conduction band of black phosphorus as ultrasonic agent,three-component black phosphorus-based nano-materials were constructed.Gold nanoparticles were deposited on the surface of black phosphorus nanosheets through in-situ reduction.The prolonged electron lifetime further improved the yield of toxic reactive oxygen species.Through the coordination of gold nanoparticles,the degradation rate of black phosphorus nanosheets slowed down,further improving the yield of toxic hydroxyl radicals and singlet oxygen mediated in the process of ultrasound.Through the nude mice model of drug-resistant breast cancer bearing tumor,the corresponding time of the maximum accumulation amount of nano-materials in the tumor site was determined.Through the polypyrrolemediated photothermal-black phosphorus-mediated sonodynamic synergistic therapy,the nanomaterials increased the mortality rate of breast cancer cells in the tumor tissue and slowed down the growth rate of tumor.During the whole treatment process,the designed nano-materials would not cause serious tissue damage,obvious blood safety and the risk of liver and kidney damage.This design idea solves the difficult problem of electronic reconstruction of conduction band of black phosphorus piezoelectric material in ultrasonic process,and provides reference for improving ultrasonic treatment effect.4.In order to reduce the potential safety of the components,a biocompatible black phosphorus-based nanocomposite was constructed by integrating biological heme into black phosphorus nanosheets through a simple mixed preparation strategy.The experimental results showed that the constructed nano-materials had the properties of consuming glutathione and catalyzing hydrogen peroxide for oxygen supply,thus increasing the production of toxic singlet oxygen,and further enhancing the cy totoxicity of photothermal on triple negative breast cancer cells.The corresponding time of the maximum accumulation amount of nano-materials in tumor location was determined by 4T1 tumor-bearing,experimental mouse model,and the anti-tumor effect was effectively enhanced by photothermal-photodynamic therapy.In addition,the death of immunogenic cancer cells induced the increase of blood inflammatory factor concentration,activated endogenous immune response behavior,and made up for the limitations of exogenous phototherapy.Therefore,this kind of nanosystem displays a new perspective for designing biocompatible nanomaterials,and provides a reference for developing biodegradable compatible nanomaterials in the field of tumor treatment.