Hydrogen tetrachloroaurate 3 haucl4

Graphite powder, dopamine (DA) hydrochloride, L-(+)-ascorbic acid (AA), uric acid (UA), citric acid (CA), glucose, potassium hexacyanoferrate (K₃[Fe(CN)₆]), phosphate buffer saline (PBS, pH 7.4, 0.1 M), and hydrogen tetrachloroaurate (III) (HAuCl₄) were purchased from Sigma-Aldrich Co. (St. Louis, MO, USA). All the other chemicals used such as sodium hydroxide (NaOH), sodium nitrate (NaNO₃), sodium carbonate (Na₂CO₃), potassium permanganate (KMnO₄), hydrogen peroxide (H₂O₂), and sulfuric acid (H₂SO₄) were obtained from Duksan Pure Chemicals Co. (Ansan, Korea). All the reagents were analytical grade and were used without further purification. Deionized (DI) water was used throughout the work.

Tetronic 1307 (T1307; molecular weight 18,000; PEO content 70 wt%) was supplied by BASF Corporation (Mount Olive, NJ, USA) and used as received. Hydrogen tetrachloroaurate(III) (HAuCl₄) and sodium chloride (NaCl) were from Sigma Aldrich (St Louis, MO, USA) and used without further purification. Distilled water was used for all experiments. All other reagents were analytical grade.