Fig. 2. (a) FCM result and the corresponding fluorescence image of the MBs involved in the TdT-FCI system without the PSA target (blank control); (b) FCM result and the corresponding fluorescence image of the MBs involved in the TdT-FCI system in the presence of 20 ng mL^–1 PSA target. In images (a) and (b), the TdT-FCI is conducted following the standard procedures as stated in the Experimental section; (c) FCM result and corresponding fluorescence image of the MBs involved in the TdT-FCI system with 20 ng mL^–1 PSA target by using mAb2–AuNPs instead of mAb2–AuNPs–ODN. All of the parameters for the FCM measurement and fluorescence imaging are the same in (a–c). Acquisition parameters of the fluorescence images: HV, 520 V; gain, 1; offset, 20%; collected fluorescence band, 500–600 nm.