Thiol-PEG4-alcohol is widely used in bioconjugation and surface modification due to its thiol group, which forms stable bonds with gold, silver, and other metals. It is commonly applied in the development of biosensors and nanomaterials, where it acts as a linker to immobilize biomolecules like proteins or peptides onto surfaces. In drug delivery systems, it serves as a spacer to enhance solubility and stability of therapeutic agents. Additionally, it is utilized in polymer chemistry to modify polymers, improving their biocompatibility and functionality for biomedical applications. Its PEG (polyethylene glycol) segment also helps reduce immunogenicity and prolong circulation time in vivo.