Role of thiol-containing polyethylene glycol (thiol-PEG) in the modification process of gold nanoparticles (AuNPs): stabilizer or coagulant?

Gold nanoparticles (AuNPs) have significant potential as biosensors and drug delivery vehicles, as well as imaging and thermotherapy agents. Thiol-containing polyethylene glycol (PEG), hereafter denoted as thiol-PEG, is widely used as a macromolecular ligand for modifying AuNPs and stabilizing them under various environments. In this work, a series of thiol-PEG-modified AuNPs (PEGylated AuNPs) with different PEG molecular weights (Mw) were synthesized.