Reduced graphene oxide

All necessary chemicals, including ascorbic acid, copper (II) nitrate, ytterbium (III) nitrate, sodium hydroxide, reduced graphene oxide, NaH₂PO₄, Na₂HPO₄, citric acid, glucose, uric acid, dopamine, sodium chloride, and calcium nitrate, were purchased from Sigma–Aldrich, and utilized exactly as they were given. All solutions were made using double-distilled water. The XPS investigation of Yb₂O₃.CuO@rGO was performed using a MgKα spectrometer (JEOL, JPS 9200) in the subsequent circumstances: pass energy = 50 eV (wide-scan) and 30 eV (narrow-scan), Voltage = 10 kV, Current = 20 mA. A PANalytical X-ray diffractometer was used to acquire X-ray diffraction (XRD) spectra with Cu Kα1/2, λα₁ = 154.060 pm, λα₂ = 154.439 pm radiation. A “Raman station 400 (Perkin Elmer)” spectrometer was used to acquire the Raman spectra. A FE-SEM (JEOL-6300F, 5 kV) was used to analyze the morphology and structural characteristics of Yb₂O₃.CuO@rGO. EDS (JEOL) was used to investigate the elemental composition of the Yb₂O₃.CuO@rGO. A JEOL JEM-2100F-UHR field emission apparatus fitted with a Gatan GIF 2001 energy filter and a 1 k-CCD camera was used to capture transmission electron microscopy (TEM) micrographs at 200 kV. Electrochemical measurements were conducted using a Zahner Zennium potentiostat.

All reagents were analytical-reagent grade and used without further purification. Deionized water was used as a diluent throughout the present work unless otherwise stated.
FAV standard (M.wt: 157.1, purity: 99.5%) was a kind gift Egyptian Drug Authority. Avipiravir® 200 mg tablets, Eva Group Limited, Cairo, Egypt, was obtained from local market. Vitamin C, Uric acid and the dosage form excipients as mannitol, magnesium stearate and carboxy methylcellulose sodium were obtained from the Egyptian Drug Authority (EDA). Stock Britton Robinson (BR) buffer solution 0.04 M was prepared according to a published procedure [35 (link)]. Graphite powder (particle dimension > 20 µM), reduced graphene oxide, sodium dodecyl sulphate (SDS), potassium ferrocyanide trihydrate K₃Fe(CN)₆.3H₂O, paraffin oil, boric acid, sodium hydroxide (NaOH), orthophosphoric acid, and glacial acetic acid have been purchased from Sigma-Aldrich. BR buffers with different pH (2–10) were prepared from the stock buffer solution by adjusting the pH using 0.2 M aqueous NaOH. Human plasma was provided by Zagazig University Hospitals, Zagazig, Egypt, and was stored frozen until used following a moderate thawing. Urine samples were taken from healthy male volunteers and kept frozen until needed.

Chemicals including Cs₂CO₃ (99.95%, Sigma Aldrich), Oleic Acid ( $\ge$ 99%, Sigma Aldrich), Octadecene (Sigma Aldrich), PbI₂ (99.99%, Sigma Aldrich), KHCO₃, Oleylamine (Sigma Aldrich), reduced graphene oxide (Sigma Aldrich), Methyl acetate, Hexane was used as received without further purification.

Furfurylamine (FU ≥ 99%) was purchased from Sigma-Aldrich (Milan, Italy). The amine was freshly distilled before use to remove the oxidized impurities, if any. Bis(3-ethyl-5-methyl-4-maleimidophenyl)methane (BISM abcr 98%, Karlsruhe, Germany), was used as the cross-linking agent. Reduced graphene oxide (rGO) was purchased from Sigma-Aldrich (Milan, Italy), and used without any purification. It is composed by >75% C and <5% N, has a surface area of 103 (m²/g) and an electric conductivity of 7111 S/m (compressed powder). N-Methyl-2-pyrrolidone (NMP), deuterated Chloroform (CDCl₃) used for ¹H-NMR studies, were all purchased from Sigma-Aldrich and used as delivered. Chloroform (CHCl₃, 99.5%) was purchased from Sigma-Aldrich (Milan, Italy) and used as received. The alternating aliphatic polyketone was synthesized according to the reported procedure [49 (link)], using 30% of ethylene and 70% of propylene to obtain the so-called polyketone 30 (PK).

Media and reagents for culture cells: L-15 Medium (1×) + GlutaMAX^TM-I, trypsin-EDTA, RPMI Medium 1640 (1×) + GlutaMAX^TM-I, DPBS, penicillin, streptomycin and fetal bovine serum Gold (FBS Gold) were provided by Gibco (San Diego, CA, USA). Kits for apoptosis detection: FITC Annexin V apoptosis detection Kit I was obtained from BD Pharmingen^TM (San Diego, CA, USA); FAM-FLICA Caspase-8 and FAM-FLICA Caspase-9 Assay were provided by ImmunoChemistry Technologies (Davis, CA, USA). Chemical treatment of cells: reduced graphene oxide (rGO) was obtained from Sigma-Aldrich (St. Louis, MO, USA), while the proteasome inhibitor (MG-132) was provided by Selleckchem (Cologne, Germany). Kit for cytotoxicity analysis: the LDH-Cytotoxicity Assay kit was provided by BioVision (St. Louis, CA, USA). The compounds for oxidative stress analysis: SDS, TCA, TBA, Folin–Ciocalteu reagent and 2′,7′-dichlorodihydrofluorescein diacetate (H₂DCFDA) were provided by Sigma-Aldrich (St. Louis, MO, USA), and GSH/GSSG-Glo^TM Assay kit by Promega (Madison, WI, USA). The compounds for ultrastructure analysis: glutaraldehyde, paraformaldehyde, cacodylate buffer, osmium tetroxide, ethanol and glycid ether were provided by Sigma-Aldrich (St. Louis, MO, USA).