How Fast Can Thiols Bind to the Gold Nanoparticle Surface?

Kinetics of gold nanoparticle surface modification with thiols can take more than one hour for completion. 7-mercapto-4-methylcoumarin can be used to follow the process by fluorescence spectroscopy and serves as a convenient molecular probe to determine relative kinetics. SERS studies with aromatic thiols further support the slow surface modification kinetics observed by fluorescence spectroscopy. The formation of thiolate bonds is a relatively slow process; we recommend one to two hour wait for thiol binding to be essentially complete, while for disulfides, overnight incubation is suggested.