To confirm the successful binding of a series of molecules, the detection of HBV was first performed using commercial SPR system. At first, 6HGBP-ScFv concentration was optimized as follows: 100, 50 and 10 µg/mL of 6HGBP-ScFv fusion protein was flowed over the gold surface, respectively. The fusion protein 6HGBP-ScFv was immobilized onto the gold surface via its intrinsic affinity with the gold as shown in Figure 2 . Interestingly, coverage of 6HGBP-ScFv on the gold surface didn't always increase with increasing protein concentrations, a maximal RU change appearing at concentrations of 50 µg/mL. From this result, 6HGBP-ScFv concentration of 50 µg/mL was chosen for subsequent experiments. Next, we checked the specificity of this platform with BSA as a negative control. First, 50 µg/mL of 6HGBP-ScFv was injected into the fluid phase, followed by 0.5 mg/mL BSA blocking of the binding sites on the fusion protein. Then, 10 µg/mL of control peptide (HOOC-CGPTGPTGPTGPTGPT-NH 2 ) as a negative control, 50, 10, 5, 2.5 and 1 µg/mL of target HBsAg were injected into respective channels, respectively. Below concentrations of 50 µg/mL for HBsAg, RU levels dropped rapidly while target concentrations as low as 2.5 µg/mL can be detected compared with the control sample. For 50, 10, 5, 2.5 and 1 µg/mL of target HBsAg, and 0.5 mg/mL of BSA, RU increase is 542.2 RU, 55.7 RU, 48.5 RU, 17.4 RU, 4.9 RU and 5.6 RU, respectively, showing an increasing trend of SPR signals with increasing concentration of target within this scope.