Myoglobin mb

Graphite (282863), H₂SO₄ (339741), KMnO₄ (223468), H₂O₂ (216763), HCl (H1758), NaNO₃ (S5506), 3-aminopropyltriethoxylsilane (APTES) solution (440140), hydrazine solution (35%) (309400), ethanolamine (NH₂CH₂CH₂OH; ≥98%) (E9508), Cr etchant (651826), Au etchant (651818), and myoglobin (MB; M0630) were purchased from Sigma-Aldrich (USA); 5′-amine modified, and 5′-amine/3′-FAM (6-carboxy fluorescein) modified cTnT aptamers (091), where the sequence of the aptamers was 5′-ATACGGGAGCCAACACCAGGACTAACATTATAAGAATTGCGAATAATCATTGGAGAGCAGGTGTGACGGAT-3′, were obtained from OTC Biotech (USA); cTnT (9202–1107) and cTnI (9202–0707) antigens were obtained from AbD-Serotec (USA); normal human serum (S1-100ML) was procured from Merck Millipore (USA); diethylpyrocarbonate (DEPC)-treated water (W2004) and dimethylformamide (DMF) (D1021; 98%) were procured from Biosesang (South Korea); PBSE (P130) was procured from Thermo Scientific (USA); and PBS (pH 7.4, 10×) was procured from Life Technologies (South Korea). DEPC-treated water was used for dilution of the aptamer stock solution, which was stored at −20 °C before use. Deionized (DI) water (18.2 MΩ) was prepared from the water purification system (Millipore).

All reagents were of high purity grade. Titanium(VI) oxide, dichlorobarium, caustic potash, perhydrol 30%, hydrogen chloride, CdSeS/ZnS alloyed quantum dots (λ = 665 nm), poly(D-glucosamine), etanoic acid, glutaric dialdehyde solution 5%, albumin bovine serum 1%, sodium dihydrogen phosphate monohydrate, caustic soda, ascorbic acid or vitamin C (VC), hydrogen borate, orthophosphoric acid, sodium hydrogenphosphate, citric acid, n-(2-Hydroxyethyl)piperazine-N′-(2-ethanesulfonic acid), monoclonal myoglobin antibodies (anti-Mb) and myoglobin (Mb) were purchased from Sigma Aldrich (São Paulo, Brazil). All aqueous solutions were prepared with water distilled in OS10LXE Gehaka equipment (São Paulo, Brazil).

Ammonium molybdate tetrahydrate (99.98%, Sigma-Aldrich, Burlington, MA, USA), thiourea (AMRESCO, Solon, OH, USA), and polyvinylpyrrolidone (Sigma-Aldrich, Burlington, MA, USA) were used to synthesize the MoS₂ NPs. Potassium hexacyanoferrate (III) (K₃Fe(CN)₆) (approx. 99.0%, Sigma-Aldrich, Burlington, MA, USA) and potassium hexacyanoferrate (II) trihydrate (K₄Fe(CN)₆) (≥99.0%, Sigma-Aldrich, Burlington, MA, USA) solution in phosphate-buffered saline (PBS) (Sigma-Aldrich, Burlington, MA, USA) was used as the electrolyte in this study. EDC and NHS were purchased from Thermo Scientific (≥99.0%, Waltham, MA, USA). Human serum (Sigma-Aldrich, Burlington, MA, USA), cysteamine (Cys) (≥98.0%, Sigma-Aldrich, Burlington, MA, USA), gp120 antibody (Sino biological, Wayne, PA, USA), and gp120 antigen (ACRO Biosystem, Newark, DE, USA) were used to fabricate the biosensor. All aqueous solutions were prepared using deionized (DI) water from a Millipore Milli-Q water purifier operating at a resistance of 18 MΩ·cm. Myoglobin (Mb) (≥90.0%, Sigma-Aldrich, Burlington, MA, USA), hemoglobin (Hb) (Sigma-Aldrich, Burlington, MA, USA), thioredoxin (Trx) (Sino biological, Wayne, PA, USA), and prostate-specific antigen (PSA) (Abcam, Cambridge, UK) were used to investigate the selectivity of the fabricated biosensor.