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 concentrations of the gp120 antigen, Hb, Mb, PSA, and Trx were fixed at 100 ng/mL. As shown in Figure 5d , the gp120 antigen had a low current value of 0.925 mA, while Hb, Mb, PSA, and Trx had high current values of 1.26 mA, 1.24 mA, 1.30 mA, and 1.26 mA, respectively. In addition, the rate of change of current value of gp120 antigen, Hb, Mb, PSA, and Trx were indicated 29.9%, 4.42%, 6.43%, 1.45%, and 4.60%. The mean value and the error bars were obtained as the standard deviation (SD) of five measurements. As shown in the results of the selectivity test, the measurement of gp120 was confirmed since the current value of the gp120 antigen, a surface protein of HIV was smaller than that of other antigens and proteins, and the electrochemical signal decreased due to selective immobilization of the gp120. The flexibility of the fabricated biosensor was confirmed by a micro-fatigue tester. Figure 6a ,b show flexibility results of a conventional bare gold electrode, Au sputter coated PET substrate, and the Au/MoS 2 /Au nanolayer on the PET substrate. In Figure 6a , the flexure extension results of the conventional bare gold electrode were 0.076 mm due to the hardness of the electrode. SiO 2 -based rigid substrates were hard to bend using applied forces due to their lack of flexibility. However, Au sputter coated PET and the Au/MoS 2 /Au nanolayer on the PET substrate showed excellent flexibility and flexure extension with 1.60 mm and 1.54 mm, respectively. These results were significantly higher than those of the conventional electrode because these electrodes were easily bent by the applied force due to their excellent flexibility. In addition, the Au sputter coated PET and Au/MoS 2 /Au nanolayer on the PET substrate had flexure strength of 92.9 MPa and 99.2 MPa, respectively, which were lower than that of the conventional gold electrode due to the excellent flexibility. As shown in Figure 6b , the conventional gold electrode was found to be rapidly damaged by strong forces due to the hardness of the electrode. However, the fabricated biosensor had a high flexure extension compared with the conventional gold electrode because of the small force applied to the substrate due to the characteristics of the flexible substrate. In addition, SWV was performed to investigate electrochemical detection performance of the bent biosensor. To confirm the detection performance, 10 ng/mL of gp120 antigen was immobilized on the Ab/Cys/Au/MoS 2 /Au nanolayer on the PET substrate. As shown in Figure S5 , the current value of fabricated biosensor before bent was indicated 1.06 mA, and after the fabricated biosensor was bent, the current value was maintained to 1.03 mA.