The alcohol-mediated synthesis has been described elsewhere. The synthesis of the Au NPs is performed by adding HAuCl4 to a mixture of water, NaOH and an alcohol. The reaction proceeds at room temperature without the need for extra chemicals to lead to colloidal dispersions of Au NPs stable for months. The synthesis is scalable. The synthesis is best performed using high purity water. The synthesis is best performed by adding HAuCl4 last from a relatively concentrated solution of HAuCl4 (at 50 mM in mQ water in this work, stored in the fridge). The base is best used from stock solution stored in plastic container (at 50 mM in mQ water in this work, stored at room temperature). The synthesis is best performed under controlled light environment. Although the synthesis does not require stirring more reproducible results are obtained using magnetic stirring (PTFE cylindrical stirrer bar, 8 x 3 mm, VWR, 442-4520) and the magnet used were cleaned with aqua regia (4:1, v:v, HCl:HNO3; to be handled and disposed of with care following the related safety procedures in place in the laboratory).