“…M-AuNPs were synthesized by a seed-assisted growth method using poly(vinylpyrrolidone) (PVP) and N , N -dimethylformamide (DMF) as reducing agents. , Au seeds, with a diameter of ∼15 nm, were synthesized by reducing AuCl 4 – with sodium citrate, according to a slightly modified published procedure . Typically, in a condenser-equipped round-bottom flask (250 mL), 100 mL of HAuCl 4 (0.01 wt %) was first heated to boiling under vigorous stirring, followed by the rapid introduction of sodium citrate (3 mL, 1 wt %), causing a color change from pale yellow to burgundy.…”