H2nao4p

Graphene oxide (GO) dispersion in water (2 mg/mL), KCl, HCl, H₂NaO₄P, HNa₂O₄P, H₂SO_4, and HAuCl₄ were purchased from Sigma-Aldrich (St. Louis, MO, USA). Potassium ferricyanide (K₃[Fe(CN)₆]) and potassium ferrocyanide (K₄[Fe(CN)₆] × 3H₂O) were obtained from Merck Co. (Darmstadt, Germany). All oligonucleotides, like ssDNA probe (5′-TTTCAACATCAGTCTGATAAGCTATCTCCC-3′), complementary ssDNA target (5′-GGGAGATAGCTTATCAGACTGATGTTGAAA-3′), along with Tris (10 mM)—EDTA (0.1 mM) called IDTE buffer were supplied from Integrated DNA Technologies, Inc. (Coralville, IA, USA). Screen-printed carbon electrodes (SPCE-DRP 110) were acquired from Metrohm DropSens, Spain, having integrated a carbon working electrode (WE) with a 4 mm diameter, a pseudo-reference electrode (silver), and a counter electrode (carbon). The Adrona Crystal EX water purification system was used for ultrapure water to wash the SPCEs after each modification step without compromising the integrity of the DNA molecules.

Graphene oxide dispersion in water at a concentration of 2 mg/mL (code: 763705), KCl (CAS no.: 7447-40-7, 99–100.5% purity), HCl (CAS no.: 7647-01-0, 36.5–38% purity), H₂NaO₄P (CAS no.: 13472-35-0, ≥99% purity), and HNa₂O₄P (CAS no.: 7558-79-4, 98–100.5% purity) were purchased from Sigma-Aldrich (St. Louis, MO, USA). Potassium ferricyanide (K₃[Fe(CN)₆], CAS no.: 13746-66-2, ≥99% purity) and potassium ferrocyanide (K₄[Fe(CN)₆]·3H₂O, CAS no.: 14459-95-1, 99–102% purity) were procured from Merck Co. (Darmstadt, Germany). From Integrated DNA Technologies, Inc. (Coralville, IA, USA) were purchased the bioreceptors for ALP (5′-CGT CAC TCT CAT ACT CCA CAT C-3′) and RUNX2 (5′-GAC GGT TAT GGT CAA GGT GAA-3′), as well as the target molecules for both biomarkers (ALP: 5′-G ATG TGG AGT ATG AGA GTG ACG-3′, RUNX2: 5′-TTC ACC TTG ACC ATA ACC GTC-3′). Following each modification, the SPCEs were thoroughly rinsed with ultrapure water obtained from a water purification system (Adrona Crystal EX, Riga, Latvia), which has a resistivity of 18.2 MΩ·cm. SPCE-DRP 110 electrodes were purchased from Metrohm DropSens, Oviedo, Spain.

Graphene oxide dispersion in water (2 mg/mL), KCl, HCl, H₂NaO₄P, HNa₂O₄P, N-(3-Dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (EDC), N-Hydroxysulfosuccinimide sodium salt (NHS), NaNO₂ and 4-aminobenzoic acid (4-ABA) were supplied by Sigma-Aldrich (St. Louis, MO, USA). Potassium ferricyanide (K₃[Fe(CN)₆]) and potassium ferrocyanide (K₄[Fe(CN)₆] × 3H₂O) were purchased from Merck Co., (Darmstadt, Germany). Single-stranded DNA probe modified with amino groups (5′-AmC6-TTT CAA CAT CAG TCT GAT AAG CTA TCT CCC-3′), single-stranded DNA target (DNAt, 5′-GGG AGA TAG CTT ATC AGA CTG ATG TTG AAA-3′) and 10 mM Tris, 0.1 mM EDTA (IDTE) buffer were acquired from Integrated DNA Technologies, Inc (Coralville, IA, USA). The SPCEs were thoroughly rinsed with ultrapure water (Adrona Crystal EX water purification system, 18.2 MΩ × cm resistivity) after each modification. Screen-printed carbon electrodes (SPCE-DRP 110) were purchased from Metrohm DropSens, Spain.