Anhydrous ferric chloride

The red araçá fruits were harvested at coordinates −31.553710°, −53.683664°, in the city of Candiota, Rio Grande do Sul, Brazil, in April 2021. Sodium Alginate with viscosity between 300–400 CPs at 20 °C was obtained from Êxodo Científica. Ethanol, glycerol, 2,2-diphenyl-1-picrylhydrazyl (DPPH), Folin-Ciocalteau, anhydrous sodium carbonate, calcium chloride, anhydrous ferric chloride, sodium acetate, hydrochloric acid, acetic acid, 2,4,6-tripiridil-s-triazina (TPTZ) were obtained from Sigma Aldrich (St. Louis, MO, USA) with analytical grade. Ultra-pure water, methanol, acetonitrile, gallic acid, cyanidin-3-glucoside, chlorogenic acid, caffeic acid, p-coumaric acid, ferulic acid, cinnamic acid, quercetin and kaempferol were purchased from Sigma Aldrich (St. Louis, MO, USA) with HPLC grade.

Caffeine (CAF) (≥99%), ciprofloxacin (CIP) (≥98.0%), anhydrous ferric chloride, and 8-hydroxypyrene-1,3,6-trisulfonic acid trisodium salt (HPTS) (≥96.0%) were obtained from Sigma-Aldrich. Fe(NH₄)₂(SO₄)₂·6H₂O (AFS) (99.0%) was obtained from PanReac. H₂SO₄ (98.0%), sodium acetate, hydroxylamine, and 1,10-phenanthroline were obtained from Synth.
Phosphate buffer solution (0.100 mol L⁻¹, pH 6.30) was prepared in water, using dibasic potassium phosphate (K₂HPO₄) and monobasic potassium phosphate (KH₂PO₄), obtained from Sigma-Aldrich. A CAF stock solution (2000 mg L⁻¹) was prepared in water, stored under refrigeration, and used for a maximum period of one week. A CIP stock solution (1000 mg L⁻¹) was prepared in methanol, with addition of formic acid, and was stored under refrigeration. An HPTS stock solution (1.00 μmol L⁻¹) was prepared in phosphate buffer and was used on the same day.
Aqueous solutions of H₂SO₄, CH₃COONa, hydroxylamine, and 1,10-phenanthroline were prepared at concentrations of 10.0% (v/v), 10.0% (w/v), 10.0% (w/v), and 0.100% (w/v), respectively. The AFS standard was weighed out and H₂SO₄ was added in order to produce a stock standard solution with 100 mg L⁻¹ of Fe(ii) and 1.00% (v/v) of H₂SO₄. Ultrapure water was used for the preparation of all the solutions.

The standard of polyphenols (purity ≥ 98%), including chlorogenic acid, caffeic acid, rutin, catechin, epicatechin, phloridzin, kaempferol 3-O-glucoside, apigenin glucoside, phloretin, procyanidin b1, and procyanidin b2, were purchased from Sigma–Aldrich Chemical Co. (St. Louis, MO, USA). Reagents used for the antioxidant tests such as gallic acid, 6-hydroxy-2,5,7,8-tetramethylchromane-2-carboxylic acid (Trolox), 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,3,5-triphenyltetrazolium chloride (TPTZ), anhydrous ferric chloride, hydrochloric acid, and sodium acetate were purchased from Sigma–Aldrich (Milan, Italy). Methanol (MeOH) and water (LC-MS grade) were purchased from Carlo Erba reagents (Milan, Italy), whereas formic acid (98–100%) was purchased from Fluka (Milan, Italy).

All reagents used to obtain the nanosystems and nanostructured coatings were purchased from Sigma-Aldrich (Merck Group, Darmstadt, Germany), if not specified, namely, anhydrous ferric chloride (FeCl₃, >99.99%), ferrous sulfate heptahydrate (FeSO₄·7H₂O, >98%), dimethyl sulfoxide (DMSO), 3-amino propyl trimethoxysilane (APTMS, 97%), and eugenol (99%). For the biological investigations, most reagents were purchased from Sigma/Merck (Steinheim, Germany), except for the fetal bovine serum (Gibco, ThermoFischer Scientific, Waltham, MA, USA) and the BD CBA Human Inflammatory Cytokines kit (Franklin Lakes, Becton Dickinson, NJ, USA).

Ascorbic acid, aluminum chloride, gallic acid, sodium hydroxide, Folin–Ciocalteu reagent, sodium carbonate, methanol, ethanol, potassium ferricyanide (K₃Fe(CN)₆), potassium ferrocyanide (K₄Fe(CN)₆), rutin, catechin, vanillin, sulfuric acid, 6‐hydroxy‐2,5,7,8‐tetramethylchlorman‐2‐carboxylic acid (trolox), α‐tocopherol, butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA), 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH), 2,2'‐azino‐bis 3‐ethylbenzothiazoline‐6‐sulfonic acid (ABTS), trichloroacetic acid, and anhydrous ferric chloride were purchased from Sigma‐Aldrich (Saint‐Louis, USA).

Polyphenolic standards, including rutin, catechin, epicatechin, chlorogenic acid, caffeic acid, procyanidin b1, procyanidin b2, phloridzin, kaempferol 3-O-glucoside, apigenin glucoside, and phloretin, were purchased from Sigma–Aldrich Chemical Co. (St. Louis, MO, USA). For the antioxidant tests, gallic acid, 6-hydroxy-2,5,7,8-tetramethylchromane-2-carboxylic acid (Trolox), 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,3,5-triphenyltetrazolium chloride (TPTZ), anhydrous ferric chloride, hydrochloric acid, and sodium acetate were purchased from Sigma–Aldrich (Milan, Italy). Methanol (MeOH) and water (LC-MS grade) were acquired from Carlo Erba reagents (Milan, Italy), whereas formic acid (98–100%) was purchased from Fluka (Milan, Italy).