Table 1.

Synthetic methods and capping agents for AuNPs of varying core sizes.

Core	Synthetic methods	Capping agents	References
1–2 nm	Reduction of AuCl(PPh3) with diborane of sodium borohydride	Phosphine	10
1.5–5 nm	Biphasic reduction of thiol capping agents	Alkanethiol	23
3.5–10 nm	Heat-induced size ripening method	Alkanethiol	26
10–150 nm	Reduction of HAuCl4 with sodium citrate in water	Citrate	24