Poly-(L-lysine) is widely used in biomedical research and applications due to its strong positive charge, which allows it to interact effectively with negatively charged cell membranes and biomolecules. It is commonly employed as a coating agent to enhance cell adhesion on surfaces, making it valuable in cell culture studies, tissue engineering, and genetic research where it serves as a transfection reagent to facilitate the delivery of nucleic acids into cells. In the food industry, it is utilized as a natural preservative, inhibiting the growth of bacteria and extending the shelf life of products. In the cosmetics industry, it is incorporated into skincare products to improve moisture retention and enhance skin smoothness. Its biocompatibility and versatility make it a key material in various scientific and industrial fields.