CD47 and neoplasm: In this study, although MTD could enhance the effective concentration of drugs at the tumor site by responsive release, it showed poor passive targeting and was easily captured by the reticuloendothelial system, while the chemical bonds on the surface of nanoparticles can be used to link with small molecules such as HA and anti-CD47 to bind receptors that are highly expressed on the surface of tumor cells to achieve active targeting of tumors.