Flexible HIV-1 Biosensor Based on the Au/MoS(2) Nanoparticles/Au Nanolayer on the PET Substrate

Shin, Minkyu; Yoon, Jinho; Yi, Chanyong; Lee, Taek; Choi, Jeong-Woo

The fabrication of a flexible biosensor composed of Ab/Cys/Au/MoS 2 /Au nanolayer on PET substrate is shown in Figure 1 . To fabricate the Au/MoS 2 /Au nanolayer on the PET substrate, the rectangular PET substrate (size 1 mm × 2 mm) was cleaned in a sonication bath for 30 min using acetone and DI water, and then completely dried with N 2 gas. After cleaning the PET, the Au/MoS 2 /Au nanolayer on the PET substrate was prepared by gold sputter and spin coater. The Au layer was formed by sputter coating on the PET substrate. Then, 200 µL of the synthesized MoS 2 NPs dissolved in DI water (concentration: 5 mg/mL) was dropped onto the Au layer and spin coated (Au/MoS 2 ) on the PET substrate at 2000 rpm for 30 s; this process was done twice. After the spin coating process, the Au layer was sputter coated once more on the MoS 2 layer. Fabrication of the Au/MoS 2 /Au nanolayer on the PET substrate was verified by FE-SEM, EDS, and AFM. To fabricate the Ab/Cys/Au/MoS 2 /Au nanolayer on the PET substrate, the gp120 antibody was immobilized on the Au/MoS 2 /Au nanolayer on the PET substrate. The fabricated electrode was washed with ethanol and DI water in preparation for the gp120 antibody immobilization. Cys (77 mg) dissolved in 10 mL of DI water (10 mM concentration) was then immobilized on the electrode by self-assembly for 3 h at room temperature. The Cys-immobilized electrode was washed with DI water to remove any unbound Cys. Then, the gp120 antibody was attached to Cys using the EDC/NHS reaction. To achieve this, 100 µL of the antibody solution (concentration: 5 µg/mL) was mixed with 100 µL of EDC (concentration: 4 mg/mL) and 100 µL of NHS (concentration: 6 mg/mL) for 1 h at room temperature. Then, the modified gp120 antibody with EDC/NHS was dropped on the Cys-immobilized electrode for 2 h at room temperature. In addition, the gp120 antibody-immobilized electrode was washed with DI water to remove any unbound gp120 antibody and dried with N 2 gas. unbound Cys. Then, the gp120 antibody was attached to Cys using the EDC/NHS reaction. To achieve this, 100 μL of the antibody solution (concentration: 5 μg/mL) was mixed with 100 μL of EDC (concentration: 4 mg/mL) and 100 μL of NHS (concentration: 6 mg/mL) for 1 h at room temperature. Then, the modified gp120 antibody with EDC/NHS was dropped on the Cys-immobilized electrode for 2 h at room temperature. In addition, the gp120 antibody-immobilized electrode was washed with DI water to remove any unbound gp120 antibody and dried with N2 gas.