Thiol-PEG5-acid is widely used in bioconjugation and surface modification due to its thiol group, which allows for specific reactions with maleimide or gold surfaces. It is commonly employed in the development of drug delivery systems, where it helps in attaching therapeutic agents to carriers like nanoparticles or liposomes. The PEG (polyethylene glycol) spacer enhances solubility and reduces immunogenicity, making it ideal for creating biocompatible conjugates. Additionally, it is utilized in the functionalization of biosensors and diagnostic tools, where it aids in immobilizing biomolecules onto surfaces for improved sensitivity and specificity. Its applications also extend to material science, where it is used to modify surfaces for better biocompatibility or to create self-assembled monolayers (SAMs) for research purposes.