Preparation of Colloidal Gold Solution
The principle of using 1%
tri-sodium citrate to reduce
hydrogen tetrachloroaurate hydrate
(HAuCl4) to prepare
colloidal gold particles of different sizes was used (Liu et al.,
2012;). One milliliter of 1% chloroauric acid was added to 100 mL of
ultrapure water, mixed well, and heated until bubbles appeared uniformly
and started rising upward, after which 2.0 mL of 1% trisodium citrate
solution was added immediately, and heating continued for 8–10 min. The
Erlenmeyer flask was carefully removed and allowed to cool to room
temperature. Ultrapure water was added to a volume of 100 mL.