(Arg)9 TFA salt is widely used in biochemical and biomedical research due to its cell-penetrating properties. It is often employed as a peptide delivery agent, facilitating the intracellular transport of various molecules, including drugs, nucleic acids, and proteins. Its ability to cross cell membranes makes it valuable in studies focused on gene therapy, drug delivery systems, and intracellular signaling pathways. Additionally, it is utilized in the development of therapeutic peptides and as a tool for studying membrane permeability and cellular uptake mechanisms. Its application extends to vaccine research, where it enhances the delivery of antigens to immune cells, improving immune responses.