Thiol-PEG5-alcohol is widely used in bioconjugation and surface modification due to its thiol and hydroxyl functional groups. The thiol group allows for strong covalent bonding with gold, silver, and other metal surfaces, making it valuable in creating self-assembled monolayers (SAMs) for biosensors and diagnostic devices. The PEG (polyethylene glycol) spacer enhances solubility, reduces non-specific binding, and improves biocompatibility, which is crucial in drug delivery systems and protein conjugation. The terminal hydroxyl group can be further modified or used for linking to other molecules, expanding its utility in polymer chemistry and the development of functionalized nanomaterials. Its applications also extend to creating hydrophilic coatings for medical devices and improving the stability of nanoparticles in biological environments.