4 aminothiophenol 4 atp

1H, 1H, 2H, 2H-perfluorodecanethiol (PFDT), dopamine hydrochloride, 4-aminothiophenol (4-ATP) and tris(hydroxymethyl) aminomethane were obtained from Sigma-Aldrich. Ethanol and acetone were obtained from Kemiou Chemical Reagent Co., Ltd. (Tianjin, China). Methylene blue (MB) was supplied by Sinopharm Chemical Reagent Co. (Shanghai, China). Gold chloride trihydrate (HAuCl₄·4H₂O) was supplied by SiYu Chemical Technology Co. (Shanghai, China). The ultrapure water (18.2 MΩ) used throughout the experiment was produced by a Milli-Q system.

For the immobilization of SARS-CoV-2 selected oligos, different cross-linkers were tested for the effective immobilization of the selective bio-recognition elements (the extracted virus RNA) on the electrode surface. Therefore, 4-amino thiophenol (4-ATP) (Sigma-Aldrich, USA), EDC/NHS coupling by 1-ethyl-3(3-dimethyl aminopropyl) carbodiimide hydrochloride (EDC) and N-Hydroxysulfosuccinimide sodium salts (NHS), (Sigma-Aldrich, USA). A mixture of 0.2 M EDC and 0.05 M NHS was used for the functionalization of the AuNPs/WO₃-modified electrode for 30 min at room temperature. For the activation of the electrode surface, diphenylamine (DPA, ACS reagent ≥ 99%, Sigma-Aldrich), 3.0 mM in ethanolic solution was used for 45 min. Additionally, the modified electrodes were functionalized using 3 mM of ethanolic solution of 4-ATP for 16 h at 4 °C to form a self-assembled monolayer (SAM)^{22 (link),23} . Afterward, the electrodes were rinsed with ethanol to remove excess non-reactive layers of ATP.

The silver nitrate (AgNO₃, 99.8%) was purchased from Sinoreagent (Shanghai, China). Tween-20 and Chloroauric acid (HAuCl₄) were obtained from Amresco (USA). Trisodium citrate and 4-aminothiophenol (4-ATP) were obtained from Sigma-Aldrich. Magnetic beads (MBs)@Streptavidin was purchased from BEAVER (Suzhou, China). The RNase Inhibitor and the NEBuffer 2.1 were obtained from the New England Biolabs (USA). Microwell plate was obtained from CORNING, USA.

Tetraethylorthosilicate (TEOS), 3-aminopropyltriethoxysilane (APTS), tetrakis(hydroxymethyl)phosphonium chloride (THPC), polyvinylpyrrolidone (PVP), phosphate buffer saline (PBS), phosphate buffer saline containing 0.1% Tween 20 (PBST), ascorbic acid (AA), chloroauric acid (HAuCl₄), hydrofluoric acid (HF), 4-aminothiophenol (4-ATP), 4-mercaptobenzoic acid (4-MBA), 1-undecanethiol (R-CH₃), 11-mercaptopundecanoic acid (R-COOH), 11-mercapto-1-undecanol (R-OH), hydrogen peroxide (H₂O₂), and 5,5′-Tetramethylbenzidine (TMB) were purchased from Sigma-Aldrich (St. Louis, MO, USA). Ethanol (EtOH), sulfuric acid (H₂SO₄), buffer pH 4.0, and aqueous ammonium hydroxide (NH₄OH, 27%) were purchased from Daejung (Sihung, Gyeonggi-do, South Korea); and ultrapure water (18.2 MΩ cm) was produced by a Millipore water purification system (EXL water purification; Vivagen Co., Seongnam, Gyeonggi-do, Korea).

d-(+)-Glucose (≥99.5%), phosphate-buffered
saline (PBS) tablets, silver nitrate (≥99.0%), gold(III) chloride
trihydrate (≥99.9%), sodium citrate dihydrate (≥99.0%), l-ascorbic acid (≥99.0%), potassium chloride (≥99.0%),
sulfuric acid (98%), methanol (≥99.9%), polyethylenimine (PEI,
MW ≈ 25000 by LS), Nafion solution (5 wt %), and 4-aminothiophenol
(4-ATP, 97%) were purchased from Sigma-Aldrich. Heme-containing, membrane-bound
bacterial glucose dehydrogenase (GDH) from Ewingella
americana was purified and characterized according
to a previously published protocol.^{39 (link),45 (link)} All aqueous
solutions were prepared in ultrapure water (resistivity of 18.2 MΩ
cm) purified by a Purelab Flex system (ELGA LabWater, High Wycombe,
UK). For whole blood analysis, blood samples from healthy donors were
collected in VACUETTE FC Mix tubes (Greiner Bio-One, Kremsmünster,
Austria). The tubes contain a mixture of additives Na₂EDTA,
sodium fluoride, citric acid, and sodium citrate, which inhibits glycolysis
and prevents coagulation. Blood collection for analysis with the biosensors
was approved by the Swedish Ethical Board (approval number 2009/180).

PS (M_w = 20000 g/mol; M_w/M_n < 1.06), PMMA (M_w = 20000 g/mol; M_w/M_n < 1.07), Rhodamine 6 G (R6G), Crystal Violet (CV) and 4-Aminothiophenol (4-ATP) were purchased from Sigma-Aldrich. Analytical reagent (A.R.) Toluene, acetone and methyl ethyl ketone (MEK) were purchased from Beijing Chemical Works. These materials were used directly without purified. Silicon wafer (P<100>, 0.3–50 Ωcm) was supplied by Wafer Works Shanghai Corp.