PEGylation of carboxylic acid-functionalized germanium nanowires.

Germanium (Ge) nanowires were produced in solution by supercritical fluid-liquid-solid (SFLS) growth and then functionalized with carboxylic acid groups by in situ thermal thiolation with mercaptoundecanoic acid. Polyethylene glycol (PEG) was grafted to the carboxylic acid-terminated Ge nanowires using carbodiimide coupling chemistry. The nanowires were characterized using attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy and transmission electron microscopy (TEM) to confirm the surface modification of the nanowires. Dispersions of PEGylated Ge nanowires in dimethylsulfoxide (DMSO) were stable for days. The PEGylated Ge nanowires were also dispersible in aqueous solution over a wide range of pH and ionic strength.