Assembly of the Test Strip
An absorbent pad was sealed using a sample pad blocking solution (PBS solution containing 0.5% PVP, 0.5% Tween-20, 2% PEG20000, 1% BSA) for 0.5–1 h and preserved in a desiccant-containing paper bag. A conjugate pad was placed in a conjugate pad blocking solution (0.75% trehalose, 0.5% sucrose, 2% BSA, 0.5% Tween-20, 0.5% TritonX-100 in PBS); then, the conjugate pad was sprayed with a colloidal gold solution and placed in an oven at 37 °C for 3 h. After complete drying, tweezers were used to gently place the coated conjugate pad in a desiccant-containing paper bag and stored at room temperature. Subsequently, the conjugate pad was sprayed with a 1:1 mixture of p30 and p72 protein monoclonal antibodies (1 mg/mL) on the control line of the nitrocellulose membrane. Additionally, p72 (0.5 mg/mL) and p30 proteins (0.1 mg/mL) were sprayed on test lines 1 (T1) and 2 (T2) of the nitrocellulose membrane, respectively.