Dextran 4,000 is a mucus rheology modifier. The dextran molecules in Dextran 4,000 can reduce the cross-link density of mucus through osmotic effects and hydrogen bond substitution, and reduce viscoelasticity and improve the mucociliary/cough clearance index by destroying the DNA-mucin network structure in mucus. Dextran 4,000 has the ability to improve the rheological properties and clearance ability of cystic fibrosis (CF) sputum, and can be used in the study of inhalation therapy or aerosol delivery of mucostatic respiratory diseases. The Dextran series of compounds are also natural polysaccharide drug carriers that can be connected to drugs through covalent bonding methods such as ester bonds, amide bonds or click chemistry, or self-assembled to form carriers such as nanoparticles and hydrogels. Dextran is biodegradable and biocompatible, and can achieve targeted delivery and controlled release of drugs. Dextran derivatives can prolong the half-life of drugs, increase local concentrations, and reduce the activity of immune clearance.