Using selenium-conjugated polyethylene glycol to enhance the stability of gold nanoparticles in biologically relevant samples

Using stabilizing agents to maintain the physicochemical properties of colloids in complex environments is crucial for their realworld applications. In this article, we describe how selenium- (Se-) terminated polyethylene glycol (PEG) can serve as a highaffinity stabilizing agent for gold nanoparticles (AuNPs). Compared to AuNPs modified with standard thiolated PEG (S-PEG), Se-PEG-coated AuNPs are much more stable under extreme conditions such as high/low pH, high salt content, and high temperatures. We demonstrate that the Se anchor can prevent the dissociation of PEG ligands from AuNP surfaces in living cells, where a higher concentration of biothiols is usually present. These results indicate that Se-PEG is an excellent stabilizing agent that may facilitate further studies on metal NPs for various complex and physiological systems.