Cetyltrimethylammonium chloride (CTAC) coated Au nanoparticles (CTAC-Au) were synthesized according to the Zheng et al. method . 0.1 mL of 0.3 M NaBH4 was rapidly added to a 5 mL solution of 0.25x10 -3 M HAuCl4 and 0.1 M CTAB. After 3 hours, 20 µL of the solution was added to an aqueous solution composed of 4 mL of 0.2 M CTAC and 3 mL of 0.1 M ascorbic acid. 200 µL of 0.01 M HAuCl4 was then rapidly injected and stirred for 20 minutes. The solution was then cleaned twice in water at 10,000 rpm before redispersion in water at a concentration with a peak absorbance of 0.5 au.