Poly-L-Lysine solution is widely used in cell culture and biomedical research as a coating agent to enhance cell adhesion to surfaces. It promotes the attachment of cells, particularly primary cells and neurons, to glass or plastic substrates, improving cell growth and stability during experiments. This property makes it valuable in tissue engineering, cell-based assays, and microscopy studies. Additionally, it is employed in the preparation of slides for immunohistochemistry, ensuring better tissue adherence and reducing sample loss. Its cationic nature also makes it useful in gene delivery systems, where it aids in binding DNA or RNA to cell membranes for transfection.