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 SWV technique was performed to investigate the electrochemical detection performance and selectivity of the fabricated biosensor. To confirm its detection, the gp120 antigen dissolved in PBS solution was immobilized on the prepared Ab/Cys/Au/MoS 2 /Au nanolayer on the PET substrate for 1 h at room temperature. The detection of the gp120 antigen at a concentration of 0.1 pg/mL to 10 ng/mL was confirmed by SWV. As shown in Figure 5a , the electron transfer reaction between the redox probe and the biosensor surface was blocked by the antigen-antibody binding on the surface of the fabricated biosensor, and the current value was decreased when the concentration of the gp120 antibody was increased. In addition, the linearity of the current value for the gp120 antigen concentration was confirmed through the results obtained from SWV. As shown in Figure 5b , the gp120 antigen ranged from 0.1 pg/mL to 10 ng/mL and showed excellent linearity with 0.973 of the coefficient of determination value (R 2 ). In general, the concentration of gp120 in HIV-infected patients is approximately 200 pg/mL to 2000 pg/mL, therefore the fabricated biosensor showed the possibility for gp120 detection in practice. The mean value and the error bars were plotted with the standard deviation (SD) from four different measurements. The detection limit of an electrochemical biosensor composed of the Au/MoS 2 /Au nanolayer on the PET substrate for HIV detection was 0.066 pg/mL based on the 3 × (S/m) method, where S is the standard deviation of the blank signal and m is slope of the linear fitting curve, and this value was compared with other electrodes shown in Table 1 . To confirm the detection ability for the gp120 antigen prepared from a real sample, human serum was mixed with the gp120 antigen, and the detection of the gp120 antigen was confirmed by SWV. For real sample analysis, the gp120 with different concentrations from 1 pg/mL to 10 ng/mL was mixed with serum. As shown in Figure 5c , in the case of the gp120 antigen prepared in serum, the current value decreased with increase in concentration, the same as the gp120 antigen dissolved in PBS. The selectivity of the Ab/Cys/Au/MoS 2 /Au nanolayer on the PET substrate-based biosensor was measured by the addition of various types of antigens and proteins including Hb, Mb, PSA, and Trx prepared in PBS solution. 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. value decreased with increase in concentration, the same as the gp120 antigen dissolved in PBS. The selectivity of the Ab/Cys/Au/MoS2/Au nanolayer on the PET substrate-based biosensor was measured by the addition of various types of antigens and proteins including Hb, Mb, PSA, and Trx prepared in PBS solution.