D glucose c6h12o6

In this work, the reagents were used without further purification. CTS (molecular weight 190–310 kDa, 75–85% degree of deacetylation and 90% purity), silver nitrate salt (AgNO₃, 99% purity) and D-(+)-glucose (C₆H₁₂O₆, 99% purity) were purchased from Sigma Aldrich^® (St. Louis, MO, USA); glacial acetic acid (C₂O₂H₄, 99.8% purity) was purchased from Fermont^® (Monterrey, N.L., México). High molecular weight PVA (146–186 kDa, 99.3% purity +99% hydrolyzed) purchased from Sigma Aldrich^® (St. Louis, MO, USA) was used. Bacterial strains Escherichia coli (E. coli) ATCC 25922 and Staphylococcus aureus (S. aureus) ATCC 25923 were used. Mueller Hinton agar was purchased from BD Bioxon (Franklin Lakes, NJ, USA).

Titanium (IV) isopropoxide (TIP; Ti(OCH(CH₃)₂)₄, purity >97%, batch No. BCBN5487V, Sigma-Aldrich, St. Louis, USA) was the precursor of TiO₂, and d-(+)-glucose (C₆H₁₂O₆, purity ≥99.5%, batch No. 129H0342, Sigma-Aldrich) was used as the carbon source. Two grams of Pluronic F-127 (batch No. BCBL7068V, Sigma-Aldrich) was dissolved in 40 mL of absolute ethanol with magnetic stirring, and 5 mL of TIP was added and dissolved in the mixture. Three grams of glucose were slowly added into the solution and stirred until it dissolved completely. The solution was kept in a static state, for precipitation. The precipitate was collected by centrifugation at 5,000 rpm, washed three times with absolute ethanol, and dried at 100 °C for 20 min. The obtained powder was calcined at 400 °C for 2 h.

All reagents and chemicals used were of analytical reagent grade. A glucose standard solution was prepared by dissolving D-(+)-glucose (C₆H₁₂O₆, Sigma-Aldrich, Saint Louis, MO, USA) in a phosphate buffered saline (PBS) pH 7.4 (Amresco Inc, Solon, OH, USA). A glucose-free Dulbecco’s Modified Eagle Medium (DMEM) (Gibco, Thermo Fisher Scientific, Waltham, MA, USA), DMEM powder (Gibco, Thermo Fisher Scientific, USA), fetal bovine serum (FBS) (Thermo Fisher Scientific, USA), and antibiotic-antimycotic (Thermo Fisher Scientific, USA) were used without further purification.
For electrode modification, a 1000 U mL⁻¹ glucose oxidase (GOD) stock solution was prepared by dissolving glucose oxidase (E.C.1.1.3.4) from Aspergillus niger, recombinant (269 U mg⁻¹, Merck, Darmstadt, Germany) in PBS and then diluted to final concentration. A single-walled carbon nanotube (SWCNT, dispersion in H₂O, Sigma-Aldrich, Saint Louis, MO, USA) and colloidal gold (20 nm, Kestrel Bio Science, Bangkok, Thailand) were sonicated for one hour before use. A 1% w/v chitosan solution was prepared by dissolving 1 g of chitosan oligomer (100 mesh, Taming Enterprise, Beijing, China) in 100 mL of 1% acetic acid solution and then purified by dialysis.

D-(+)-Glucose (C₆H₁₂O₆) (Sigma Aldrich, CAS Number: 50-99-7), potassium hydroxide (KOH) (Sigma Aldrich, CAS Number: 1310-58-3), hydrochloric acid (HCl) (Sigma Aldrich, CAS Number: 7647-01-0), platinum (II) acetylacetonate (Pt(acac)₂) (Sigma Aldrich, CAS Number: 15170-57-7), carbon black (CB) (Alfa Aesar, CAS Number: 1333-86-4), poly(tetrafluoroethylene) (PTFE) (ACROS, CAS Number: 9002-84-0), N-methyl-2- pyrrolidone (NMP) (ACROS, CAS Number: 872-50-4) and Nafion NRE-212 membrane 0.05 mm thick (Alfa Aesar, CAS Number: 31175-20-9) were used as received without purification.

The chemicals used in this work include potassium hydroxide (KOH, 99%) flakes and D-(+)-glucose (C₆H₁₂O₆, 99.5%) powders purchased from Sigma-Aldrich, which were separately dissolved in deionized water to form aqueous solutions of suitable concentrations for use in the electrochemical tests for glucose detection. The deionized water used was generated from Milli-Q system with ρ = 18.2 MΩ·cm.

C-doped TiO₂ was synthesized by the sol-gel method [23 (link)]. First, 2 g of Pluronic^® F127 (Sigma-Aldrich, St. Louis, MO, USA) was dissolved in 40 mL 95% ethanol completely with vigorous stirring. Then, 5 mL titanium(IV) isopropoxide (TIP, Ti(OCH(CH₃)₂)₄, purity > 97%, Sigma-Aldrich) was added into the solution with magnetic stirring of 600 rpm. An amount of 3 g of D-(+)-glucose (C₆H₁₂O₆, Sigma-Aldrich), which was used as the carbon source, was dissolved in 6 mL ddH₂O. Then, the glucose solution was dropped into the TIP/Pluronic^® F127 solution. The mixed solution was kept vigorously stirring at room temperature for 30 min. The precipitate was collected by centrifugation at 5000 rpm and washed with 95% ethanol for three times. The precipitate was then calcined at 400 °C for 2 h to obtain particles.

The following chemicals were obtained from Sigma Aldrich (USA): D-(+)-glucose (C₆H₁₂O₆, 99.5%), sulfuric acid (H₂SO₄, 98%), and gold (III) chloride hydrate (HAuCl₄·3H₂O, 99.9%). The Nafion™ perfluorinated resin solution was also purchased from Sigma Aldrich (USA). For the electrochemical oxidation of glucose, a neutral pH solution of 0.1 M phosphate-buffered saline (PBS) with a pH of 7.4 was prepared. The PBS solution was made by dissolving disodium hydrogen phosphate (Na₂HPO₄) and monopotassium phosphate (KH₂PO₄) in distilled water, which was obtained from SolvAchim (Casablanca, Morocco). A stock solution of 100 mM glucose was prepared in the 0.1 M phosphate buffer solution (PBS) and stored at 4 °C.