2.4. Preparation of acridinium ester labeled anti‐human free CT‐1 antibody (AE‐Ab)

Briefly, anti‐human free CT‐1 antibody solution was diluted to 0.16 mg/mL by 0.1 M PBS (PH:7.4). Then, the antibody solution was reacted with 10 μL acridinium ester solution (0.5mM) previously dissolved in anhydrous dimethyl formamide (DMF). The reaction solution was mixed well at room temperature for 30min. The AE‐Ab solution was also purified by sephadex G‐75 Chromatography column. The purified AE‐Abs solution containing 0.02% sodium azide and 0.25% BSA was stored at −20℃.