Chloroauric acid trihydrate

Chloroauric acid trihydrate and trisodium citrate dihydrate were obtained from Alfa Aesar and used without further purification. The PVA 3 mm filament (Ultimaker) was obtained from Makerpoint. A Shimadzu UV1601 UV–vis spectrometer was used for the UV–vis study. The samples were imaged in a JEOL 1400Plus TEM operating at 120 kV. The mean aspect ratio of the AuNPs was calculated by measuring approximately 800 particles from 24 micrographs. A TE instruments DMA Q800 instrument was used for the mechanical analysis of the plastics using the stress/strain program with a force ramp rate of 1 N/min at isothermal (25 °C) temperature. Four samples of the pure PVA and four samples of the AuNP–PVA materials were tested, where each sample was also flipped upside down and the stress/strain was recorded again. The average of the measurements was used in Figure 2c with the standard deviation shown as the error bar.

Silver nitrate, sodium citrate, KI, KCl, glutathione disulfide in the oxidized form (GSSG), and ethidium bromide (EtBr) were all purchased from Sigma-Aldrich (Sigma Aldrich Inc., St. Louis, MO, USA). DL, 1, 4-dithiothreitol (DTT) were purchased from Acros Organics (Geel, Belgium). Chloroauric acid trihydrate was purchased from Alpha Aesar (Thermo Fisher Scientific, Ward Hill, MA, USA). None of these chemical reagents were further purified before being used. Double-distilled water (ddH₂O) was used in all of the experiments.

Chloroauric acid trihydrate (HAuCl₄•3H₂O) (99.99%) was obtained from Alpha Aesar (Thermo Fisher Scientific, Ward Hill, MA, USA). Sodium citrate dihydrate (C₆H₅Na₃O₇•2H₂O) (>99.0%) was purchased from J. T. Baker (J.T. Baker, Philipsburg, NJ, USA). DL, 1, 4-dithiothreitol (DTT) (99%) was purchased from Acros Organics (Geel, Belgium). Silver nitrate (≥99%), glutathione disulfide (GSSG) (≥99%), sodium borohydride (99%), and oxidized DTT (≥98%) were all purchased from Sigma Aldrich (Sigma Aldrich Inc. St. Louis, MO, USA).