Thiol-PEG8-Thiol is a bifunctional polyethylene glycol derivative with a structure consisting of two thiol groups (-SH) connected by an octaethylene glycol (PEG8) flexible segment. Its molecular formula is C₄₇H₅₆N₄O₄S (an example; actual formula may vary depending on the synthesis route). The production process employs precisely controlled ring-opening polymerization and terminal functional group modification techniques to ensure monodispersity of the PEG segment and thiol reactivity, achieving a purity of over 99%. This molecule exhibits balanced hydrophilic and hydrophobic properties. The thiol groups can undergo specific covalent reactions with maleimides, gold/silver surfaces, etc. It finds wide application in nanomaterial surface functionalization, construction of protein-drug conjugates, and development of high-sensitivity biosensors, serving as a key linking tool in biomedical and materials science fields.