6 mercaptohexanoic acid 6 mha

MXene, synthesized according to a previous protocol [18 (link)], was diluted to 1 mg/ml with deionized water (DIW). The AuMGE was manufactured by SNI technology (South Korea) based on previous research [19 (link)], and the AuMGE surface was ultrasonically cleaned with acetone for 10 min. Then, 10 μl of 5% aminopropyltriethoxysilane (Sigma-Aldrich, USA) was applied to AuMGE for 11 min to form an NH₂ layer, and silane was activated by heating in an oven at 70 °C for 1 h. Thiol-modified (SH–) groups were generated by reacting 10 μl of 6-mercaptohexanoic acid (6-MHA, Sigma-Aldrich, USA) and activated AuMGE for 1 h. Then, 10 μl of 1 mg/ml MXene was added and maintained at room temperature for 12 h for the reaction to occur. Finally, 10 μl of 5% mercaptopropyltriethoxysilane (MPTES, Sigma-Aldrich, USA) was applied for 11 min to create a SH group-modified layer.
SH group-modified Zika virus envelope protein aptamer was diluted to 1 μM with DIW, and 10 μl was reacted with the SH layer of AuMGE for 3 h to deposit the aptamer and bind it through self-assembly. All reactions were carried out at room temperature, and the residue was removed with DIW and N₂ gas.

The Au substrates (Au (43 nm)/Cr (2 nm)/SiO₂ (200 nm) Si (p-type) wafers) were prepared to carry out the AFM and CV experiments to manufacture the working electrode (G-MEK, Seoul, Korea). Negative photoresist (Su-82), developer, and stripper for the photolithographic process were purchased from Microchem (Westborough, MA, USA). Pt wire for the counter electrode and the Ag/AgCl reference electrode were purchased from BAS (West Lafayette, IN, USA) to conduct the electrochemical experiments. The 6-Mercaptohexanoic acid (6-MHA) and hemoglobin extracted from horse heart were purchased from Sigma-Aldrich (Saint Louis, MO, USA). A 0.2 mg/mL hemoglobin solution was prepared and dilluted in 10 mM HEPES buffer at pH 7.2. For the electrochemical experiment, hydrogen peroxide (H₂O₂) was purchased from Daejung Chemical and Metals Co. Ltd. (Siheung-si, Korea). The gold nanoparticles (20 nm and 60 nm) were purchased form BBI for electrochemical experiment and SERS experiment, respectively (Cardiff, UK).