Thiol-PEG2-acid is widely used in bioconjugation and surface modification due to its reactive thiol group and hydrophilic polyethylene glycol (PEG) spacer. It is commonly employed to functionalize nanoparticles, proteins, and peptides, enhancing their stability and solubility in aqueous environments. The thiol group allows for specific attachment to gold surfaces or maleimide-functionalized molecules, making it valuable in the development of biosensors and diagnostic assays. Additionally, it is utilized in drug delivery systems to create targeted therapies by linking therapeutic agents to carriers. Its PEG spacer minimizes non-specific interactions and improves biocompatibility, making it suitable for biomedical applications.