DEAE-Dextran is widely used in molecular biology and biochemistry for transfection, a process where nucleic acids like DNA or RNA are introduced into cells. It serves as a cationic polymer that binds to the negatively charged nucleic acids, forming complexes that can be taken up by cells more efficiently. This method is particularly useful for transient gene expression studies in mammalian cells. Additionally, DEAE-Dextran is employed in chromatography as an ion-exchange resin for the purification of proteins and other biomolecules, leveraging its ability to bind negatively charged molecules. It is also utilized in vaccine development as an adjuvant to enhance immune responses.