An electrophoretic method for selection of conditions for production of electrophoretically uniform protein colloidal gold complexes

An electrophoretic method was developed to determine the conditions required for production of electrophoretically uniform protein-colloidal gold complexes from monodisperse colloidal gold (Au) and electrophoretically uniform protein. The method is based on the electrophoretic migration of protein-Au complexes in agarose. The results demonstrate that two variables, the pH of adsorption and the quantity of protein added, can be manipulated to vary the electrophoretic mobility of the resulting protein-Au complexes. Thus, agarose gel electrophoresis can be used to select the pH of adsorption and the quantity of protein required to produce electrophoretically uniform protein-Au complexes. This new electrophoretic mobility test can be used in place of or in addition to the classical procedure of Zsigmondy and its many variations, both visual and spectrophotometric. The procedure described is also useful for electrophoretic comparison of small quantities of various protein-Au samples.