Selective glucose oxidation on gold colloids

Gold colloids were obtained by reducing tetrachloroauric acid (HAuCl4) with sodium borohydride (NaBH4) in the presence of polymers as stabilising agents in an aqueous solution. The catalytic activity of the colloids was tested in the selective oxidation of glucose to gluconic acid. A total selectivity towards gluconic acid and the possibility to recycle the colloids by using chitosan as stabilising polymer were found. The catalytic properties of gold supported on titania were compared to those of the gold colloids in glucose oxidation.