Preparation of gold colloid using pyrrole-2-carboxylic acid and characterization of its particle growth - PEGylated gold colloid as bionanomaterials

Gold colloid was prepared by reduction of tetrachloroaurate using pyrrole-2-carboxylic acid in the presence of alpha-methoxy-omega-mercaptoethyl-poly(ethylene glycol). The shape and size of the obtained gold colloids were monitored by absorption spectroscopy and transmission electron microscopy during the reduction reaction. In the early stage of the reducing reaction, large fluffy particles with diameters >100 mu m were observed. Some of these large particles had rectangular parallelepiped shapes. However, the mean particle size decreased with increasing time. Eventually, these large, non-round-shaped particles disappeared almost completely, and uniform round-shaped particles with a mean diameter of 10.5 nm became dominant.