SH-PEG-SH, a polyethylene glycol (PEG) with thiol (SH) groups at both ends, is widely used in bioconjugation and surface modification due to its reactive thiol end groups. It is commonly employed to link biomolecules, such as proteins or peptides, to surfaces or other thiol-reactive molecules, enhancing stability and functionality. In drug delivery systems, it serves as a crosslinker to create biocompatible and biodegradable hydrogels, enabling controlled release of therapeutic agents. Additionally, it is utilized in nanotechnology for functionalizing nanoparticles, improving their dispersion and targeting capabilities. Its ability to form disulfide bonds makes it valuable in creating redox-responsive materials for applications in biosensing and tissue engineering.