The same seeds as described above were used. For the growth solution, 10 ml of 0.1 M CTAB was mixed with 50 l gold stock solution (0.1 M). Next, 100 l of 0.01 M AgNO3 was added, followed
by 70 l of 0.1 M AA; the solution quickly turned from dark yellow to clear and colourless. To this solution 50 l of a 0.1 M HCl solution was added, resulting in a pH of 2–3.
After that, 24 l of CTAB capped seeds were added;the resulting solution was left overnight at 25 ◦C.
Purification was done by centrifugating twice at 10,000 rpm for 10 min.
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