Bentonite nanoclay

Rojo Duro onion samples were provided by the farm “Azienda Agraria Turrioni Fiorella” (Cannara-Perugia, Italy). The extract from OL was prepared about five months after the onion harvesting.
Folin–Ciocalteu reagent, 2,4,6-tris(2-pyridyl)-s-triazine (TPTZ), 6-hydroxy-2,5,7,8-tetramethyl-2-carboxylic acid (Trolox), 2,2-diphenyl-1-picrylhydrazyl (DPPH), hydrochloric acid (HCl), ferric chloride (FeCl₃), sodium acetate (NaOAc), sodium carbonate (Na₂CO₃), acetic acid (AcOH), gallic acid (GA) and ethanol (EtOH) and bentonite nanoclay were purchased from Sigma-Aldrich (Milano, Italy). Polyvinylpyrrolidone K90 (PVP K90) was furnished by ISP (Baar, Switzerland). Sodium carboxymethylcellulose (NaCMC) was purchased from Caelo (Hilden, Germany). Ultrapure water was obtained from a reverse osmosis based Milli Q System (Millipore, Milano, Italy). Other reagent grade chemicals and solvents were used without further purification. Ultrapure water was sterilized in a steam autoclave (121 °C, 2118 millibar absolute pressure and relative pressure 1360 millibar).
The simulated wound fluid (SWF) pH 6.5 was prepared by dissolving 8.30 g of NaCl and 0.28 g of CaCl₂ in 1000 mL of ultrapure water [36 (link)].

Graphite waste was collected from Qatalum (Doha, Qatar). H₂SO₄, HNO₃, ammonia, and bentonite nanoclay were purchased from Sigma-Aldrich (Munich, Germany).