Poly vinylpyrrolidone pvp

Poly(vinylpyrrolidone) (PVP) with an average Mw 1300 kDa (>99%) was obtained from Alfa Aesar (Ward Hill, MA, USA). PVP with Mw 360 kDa and Mw 40 kDa, 2-hydroxyethyl methacrylate (HEMA) (>97%), α,α′-Azoisobutyronitrile (AIBN), and N,N-methylene-bis(acrylamide) (MBA) (>99%) were purchased from Sigma-Aldrich (St. Louis, MI, USA). HEMA was purified by filtration through an activated basic alumina column, while AIBN was purified by recrystallization from methanol prior to use. Maleic anhydride (MA) (>99%) was obtained from Fluka (New Rochelle, New York, NY, USA). For pH solution modification, ammonium hydroxide solution 33% Riedel-de Haën, (New Rochelle, New York, NY, USA) was used. HNO₃ (70%, Carlo Erba, Cornaredo, Italy) was employed for releasing solutions from gels. MQ water^® and ultra-pure water were used when necessary.

The reagents used to prepare the precursor solutions were as follows: titanium tetraisopropoxide (TTIP, ≥98.0%, GR, Junsei, Tokyo, Japan), acetyl acetone (ACAC, ≥99.0%, GR, Junsei, Japan), ethyl alcohol (EtOH, ≥99.5% EP, Daejung, Siheung, Korea), polyvinyl pyrrolidone (PVP, M.W. 1,300,000, Alfa Aesar, Haverhill, MA, USA), Fe(NO₃)₂·9H₂O (GR, ≥ 99.0%, Kanto Chemical, Japan), titanium(IV) oxide (P25, ≥95.0%, Sigma-Aldrich, St. Louis, MO, USA), methylene blue ( ≥82.0%, Sigma-Aldrich, St. Louis, MO, USA), and acid-orange 7(AO7, ≥85.0%, Acros organics, Suwanee, GA, USA).

Polysulfone (PSf, molecular weight of 75-81 KDa) was supplied by Solvay Advanced Polymers (Winder, GA, USA). N-methyl-2-pyrrolidone (NMP, Merck Pte Ltd, Singapore) was used as the solvent to prepare the polymer dope. Polyvinyl pyrrolidone (PVP, 1300 kDa, Alfa Aesar, Ward Hill, MA, USA) and lithium chloride (LiCl, Sinopharm Chemical Reagent Co. Ltd., Beijing, China) were used as additives for the fabrication of the support. Monomers for interfacial polymerization included trimesoyl chloride (TMC, Sinopharm Chemical Reagent Co. Ltd., Beijing, China) and m-phenylenediamine (MPD, Sigma-Aldrich). Sodium dodecyl sulfate (SDS, Merck Pte Ltd, Singapore) was the additive chosen for the interfacial polymerization. n-hexane (Fisher Scientific Pte Ltd, Singapore) was the organic solvent chosen for the dissolution of TMC. All chemicals were used as received.

Ciprofloxacin powder (CIP; Mw = 331.35; purity > 98%) was donated by Teva Pharmaceutical Works Ltd. (Debrecen, Hungary) for research work. Polyvinylpyrrolidone (PVP; Mw = 1,300,000) was purchased from Alfa Aesar (Heysham, UK). The solvents for the ES solutions, the ethanol (99.99% purity), and the glacial acetic acid were obtained from Fisher Scientific (Loughborough, UK) and Sigma-Aldrich (Hamburg, Germany), respectively. As a reference for the in vitro dissolution studies, commercially available CIP-containing filmcoated per os tablets (Ciprinol^® 250 mg, KRKA, d. d., Novo mesto, Slovenia) were used. Acetonitrile was purchased from Molar Chemicals (Halasztelek, Hungary). The thiazolyl blue tetrazolium bromide (MTT) reagent and sodium dodecyl sulfate were obtained from Sigma-Aldrich (Hamburg, Germany). Phosphate buffer solutions (PBS; pH 2.8 and pH 7.4) were prepared in-house. All other chemicals were analytical grade, and purified water was used.

Ciprofloxacin base (CIP; Mw = 331.35; purity >98%) was gifted by Teva Pharmaceutical Works Ltd. (Debrecen, Hungary). Polyvinylpyrrolidone (PVP) (Mw = 1,300,000) was obtained from Alfa Aesar (Lancashire, United Kingdom). Ethanol (99.99% purity) and chloroform (99.8% purity) were purchased from Fisher Scientific (Loughborough, United Kingdom).
Phosphate buffer solutions (PBS, pH 7.4 and 6.8) were prepared in-house as follows. To prepare 1 L of the pH 7.4 PBS, 1.44 g disodium phosphate dihydrate (Na₂HPO₄ × 2 H₂O), 0.12 g potassium dihydrogen phosphate (KH₂PO₄), 8.00 g sodium chloride (NaCl), and 0.20 g potassium chloride (KCl) were dissolved in approximately 0.9 L of distilled water. Then the pH was adjusted to 7.4 using aqueous solutions of NaOH, bringing the buffer up to a volume of 1 L. For the preparation of 1 L of the pH 6.8 PBS, 6.8 g KH₂PO₄ was dissolved in 900 mL of distilled water before mixing 77.00 mL of aqueous solutions of NaOH (0.2 M). The pH was adjusted to 6.8 using the NaOH solution. All used chemicals were purchased from Sigma-Aldrich (Budapest, Hungary).
All other chemicals were analytical grade, and distilled water was used.

Cerium nitrate hexahydrate (Alfa Aesar), polyvinylpyrrolidone (PVP, MW 1,300,000, Alfa Aesar), and N′,N-dimethylformamide (DMF, VWR Life Science) were used to produce undoped ceria nanofibers. Copper acetate monohydrate (Sigma Aldrich), nickel nitrate hexahydrate, iron nitrate nonahydrate, cobalt nitrate hexahydrate, manganese nitrate tetrahydrate, and lanthanum nitrate hexahydrate (all from Alfa Aesar) were used for doping the oxide. All reagents were used without any further purification.