| Recently,phosphorus-based nanomaterials have attracted more and more attention due to their high biological activity and good biological safety.One of the very important types of phosphorus-based nanomaterials is single-element phosphorus materials.In this paper,two new two-dimensional phosphorus nanomaterials,black phosphorus nanosheets and red phosphorus nanosheets,have been synthesized,and their new applications in biomedicine have been explored from three different perspectives.First,we prepared black phosphorus nanosheets through liquid exfoliation technique and black phosphorus-corona complex through its interaction with plasma protein.Then,proteomics was carried out to classify and analyze the protein on the corona.Proteomics analysis revealed that 70% of the proteins in the corona are immune-related.Subsequently,the interaction between black phosphorus-corona complex and immune cells was explored,and the results showed that black phosphorus-corona complex can effectively activate the calcium signaling pathway of macrophages,thereby inducing macrophages polarization.Furthermore,black phosphorus-corona complex enhanced the phagocytosis ability of macrophages and the ability to secrete anti-tumor cytokines.Finally,through mouse tumor models,we found that black phosphorus could also induce macrophage polarization and enhance the anti-tumor activity of macrophages in living animal models,indicating that black phosphorus has potential immunotherapy functions.During our research,we found that black phosphorous nanosheets would easily react with water and oxygen in an aqueous environment and finally degraded tophosphate group.The intermediate product formed in the oxidation process,oxidized black phosphorus nanosheets,has a unique structure similar to zoledronic acid.By comparison with graphene,we found that black phosphorus nanosheets could bind hydroxyapatite after oxidization,indicating that oxidized black phosphorus nanosheets have bone targeting ability.Through TRAP staining and resorption pits analysis,we found that oxidized black phosphorus can effectively inhibit the formation and functions of osteoclasts.Subsequent studies on its mechanism showed that oxidized black phosphorus can effectively interfere with the NF-κB pathway of osteoclasts;signaling pathway analysis results showed that oxidized black phosphorus inhibits the phosphorylation of proteins such as p38,IKK and p100,and significantly inhibits NF-κB pathway in osteoclasts,thereby preventing osteoclasts cell precursor cells differentiating into osteoclasts and effectively inhibiting the function of osteoclasts.Subsequently,we established osteoporosis model with mice to verify the therapeutic potential of oxidized black phosphorus for osteoporosis.Animal model results show that oxidized black phosphorus can increase the density of bone microstructure,the number of bone trabeculae,and reduce the dissolution of bone,indicating that oxidized black phosphorus could be used as antiresorptive agent for osteoporosis treatment.Finally,we tried to synthesize the red phosphorous nanosheets with hydrothermal method.Through transmission electron microscopy,atomic force microscopy,X-ray photoelectron spectroscopy and other physical and chemical characterization methods,we have proved that the red phosphorous nanosheets have an amorphous structure with a thickness of only 2 nm.Moreover,metal atom-doped red phosphorus nanosheets could be constructed in this strategy.And,we have successfully synthesized Fe(II)and Ni(II)-doped red phosphorus nanosheets.On the other hand,by screening the anti-tumor activity of red phosphorus nanosheets,we found that red phosphorus nanosheets have the strongest inhibitory effect on liver cancer cells A549,while it showed no toxicity to normal cell lines.The anti-tumor mechanism analysis showed that red phosphorus nanosheets can induce overexpression of reactive oxygen species in A549 cells and cause DNA damage,which in turn caused drastic autophagy in tumor cells and led to cell death.The in vivo results show that layered red phosphorus can effectively inhibit the growth of tumor tissues.Through tissue immunofluorescence analysis,we found that there was significant autophagy activity in tumor tissue.More importantly,the red phosphorus nanosheets will not produce toxicity to the main organs of mice at effective concentrations,indicating that the red phosphorus nanosheets have good biological safety.Therefore,through new perspectives,we have discovered that black phosphorus not only has immunotherapy functions,but its oxidation intermediates can also be used for osteoporosis therapy.In addition,when red phosphorus is in a two-dimensional form,it would exhibit a high selective killing ability on tumor cells,especially lung cancer cells,indicating that red phosphorus is a highly effective chemotherapeutic agent.Our research provides new ideas for the biomedicine application of phosphorus-based nanomaterials. |
