Fast loading of PEG–SH on CTAB-protected gold nanorods†
This study aimed to develop a rapid and simple method to functionalize gold nanorods using thiolated polyethylene glycol (PEG–SH), which can be used for plasmonic sensing and other applications. PEG was successfully loaded onto CTAB-protected gold nanorods in 30 min using Tris buffer with a pH of 3.0. In contrast, the functionalization of gold nanorods in water induced the aggregation of gold nanorods and produced a floating layer of randomly aggregated nanorods at the water–air interface. The concentration of mPEG–SH has no significant influence on the optical properties of gold nanorods modified by the proposed method. The results show that the PEG-modified gold nanorods could sustain 1.0 M NaCl, whereas CTAB-protected gold nanorods aggregated immediately after the addition of NaCl. Compared with the traditional 24 h method in a CTAB/carbonate solution, the proposed method offers a higher loading speed and a higher coverage density of PEG on gold nanorods. It was also found that the PEG-modified NR-610 could form a very uniform monolayer on silicon by slow evaporation of the water content. This method may open a new route for fabricating substrates for bio-medication, detection of food contaminants, and environmental monitoring.