Improved synthesis of tetraethylene glycol-derived thiol for monolayer-protected gold nanoparticles

Abstract

Improved synthesis of ω-functionalized mercapto-tetraethylene glycols and single-phase synthesis of gold nanoparticles are described. Tetraethylene glycol is converted to mercaptotetraethylene glycol through thioacetate-protected tetraethylene glycol. The formation of disulfide byproducts are easily prevented by isolating the protected mercaptan which can be stored and quickly de-protected when needed. More importantly, mercaptotetraethylene glycol allows the simple one-step preparation of protected, water-soluble gold nanoparticles within a single alcoholic phase. This method avoids the problem of persistent ionic contamination from residual phase-transfer agent. These types of nanoparticles could provide a good starting material for biological applications due to their enhanced hydrophilicity and strong stability.