Sodium phosphate dibasic na2hpo4

α-TCP powder was acquired from RMS Foundation, Switzerland. The particle size distribution (in volume average) was d10 = 2.7 ± 0.1 µm, d50 = 9.4 ± 1.0 µm and d90 = 87 ± 27 µm [19 (link)]. PVA fibers were purchased from STW (Type F PVA 401–100, Schenkenzell, Germany) and reported by the manufacturer to have a tensile modulus of 40 GPa and a tensile strength of 1.83 GPa. The fibers were 0.9 mm in length and 13 µm in diameter. Sodium phosphate dibasic (Na₂HPO₄) was bought from Sigma Aldrich (St. Louis, MO, USA).

Di(ethylene glycol) methyl ether methacrylate (MeO2MA 95%, Aldrich), oligo(ethylene glycol) methyl ether methacrylate (OEGMA, terminated by 8 EG units with Mn = 475 g·mol⁻¹), methacrylic acid (MAA) and oligo(ethylene glycol) diacrylate (OEGDA, number average weight Mn = 250 g·mol⁻¹) were supplied by Sigma-Aldrich (St. Louis, MI, USA) and used without any purification. Potassium persulfate (KPS 99%, ABCR), as initiator, was used as received. Buffers were prepared using citric acid and sodium phosphate dibasic (Na₂HPO₄), both supplied by Sigma-Aldrich. Diethylamino hydroxybenzoyl hexyl benzoate (DBBH), benzophenone-4, and salicylic acid were kindly supplied by LVMH (St Jean de Braye, France). Purified water from the Millipore Milli-Q system (Lormont, France) and ethanol (VWR Chemicals, Rosny-sous-Bois, France) were used throughout the work.

Electric eel acetylcholinesterase (AChE, EC 3.1.1.7), equine serum butyrylcholinesterase (BChE, EC 3.1.1.8), 5,5’-dithio-bis-2-nitrobenzoic acid (DTNB), and sodium phosphate dibasic (Na₂HPO₄) were purchased from Sigma-Aldrich (St. Louis, MO, USA). S-butyrylthiocholine chloride (BTCC) from Sigma-Aldrich (Buchs, Switzerland), acetylthiocholine iodide (ATCI) from Sigma-Aldrich (Dorset, UK) and sodium phosphate monobasic (NaH₂PO₄) from Sigma-Aldrich (Munich, Germany) were purchased. Tacrine hydrochloride from Cayman Chemical Company was used as the standard drug, and absolute ethanol from Merck Emsure^® Germany, was used as the solvent. The reagents and solvents for the synthesis work were obtained commercially from Sigma-Aldrich Corporation (St. Louis, MO, USA) and used without any further purification.

Metformin hydrochloride (97%) was purchased from Sigma Aldrich Chemie Gmbh (Steinheim, Germany), sodium acetate (CH₃COONa, ≥99.0%) was obtained from Silal Trading SRL (Bucharest, Romania), sodium phosphate dibasic (Na₂HPO₄, ≥99.0%) was obtained from Sigma-Aldrich Chemie GmbH (Steinheim, Germany), potassium dihydrogen phosphate (KH₂PO₄, ≥99.5%) was obtained from Utchim SRL (Râmnicu Vâlcea, Romania), potassium chloride (KCl, ≥99.0%) was obtained from Chemical Company S.A. (Iasi, Romania), orthophosphoric acid (H₃PO₄, ≥85%) was obtained from Chemical Company S.A. (Iasi, Romania), glacial acetic acid (CH₃COOH, 99.84%) was obtained from Chimreactiv SRL (Bucharest, Romania), hydrochloric acid (HCl, ≥37.0%) was obtained from Chemical Company S.A. (Iasi, Romania), sodium hydroxide (NaOH, 98.5%) was purchased from Chemical Company S.A. (Iasi, Romania), gradient grade methanol and acetonitrile (Hiposolv Chromanorm) were obtained from VWR International S.A.S. (Fontenay-sous-Bois, France). Ultrapure water (resistivity 18.2 MΩ·cm) was obtained from a local pharmaceutical company. Industrial M-HCl tablets with a content between 500 mg and 1000 mg were purchased from the local market (pharmacy).

Sodium phosphate dibasic (Na₂HPO₄) and sodium phosphate monobasic (NaH₂PO₄) for the phosphate buffers preparation were purchased from Sigma-Aldrich (Paris, France). Multi-walled carbon nanotubes (MWCNTs; Ø = 9.5 nm, purity > 95%, 1.5 μm length) were obtained from Nanocyl and used for laboratory-made buckypaper (L_bp) fabrication. Commercial MWCNT proprietary blend buckypaper (C_bp) was obtained from Nano-TechLabs, Inc (reference number NTL-12218). N,N-dimethylformamide (DMF, 99.9%), iron-protoporphyrin (hemin; ≥97%) and 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS, ≥98%) were purchased from Sigma-Aldrich. Bilirubin oxidase (BOx) from Myrothecium verrucaria (E.C. 1.3.3.5; 1.96 U mg⁻¹) was purchased from Amano Enzyme. Oxygen and argon were purchased from Air Liquide (Paris, France).

All DNA molecules were synthesized by MDBio, Inc. The 20-nm AuNPs and the 1-μm streptavidin-coated polystyrene beads were purchased from Nanocs and Bangs Laboratory, Inc., respectively. Polydimethylsiloxane (PDMS) (Sylgard 184) was purchased from Dow Corning. Other chemical and biochemical products, including sodium chloride (NaCl), sodium phosphate dibasic (Na2HPO4), sodium phosphate monobasic (NaH2PO4¬), sodium dodecyl sulfate (SDS), tris(2-carboxyethyl)phosphine hydrochloride (TCEP-HCl), polyvinylpyrrolidone (PVP) (MW 40,000), (+)-Sodium L-ascorbate (L-SA), silver nitrate (AgNO₃), Tween 80, phosphate buffer saline (PBS), melamine, sodium thiocyanate (NaSCN) were all obtained from Sigma-Aldrich.