A label-free electrochemiluminescence cytosensors for specific detection of early apoptosis.

A novel electrochemiluminescence (ECL) cytosensors was developed for the detection of early apoptotic cells by the specific interaction between Annexin V and phosphatidylserine(PS) based on ECL signal of CdS-QDs. Immobilization of Annexin V on a L-cysteine-capped CdS-QDs/Polyaniline nanofibers (PANI-NF) resulted in the stable and high loading of Annexin V on the sensor surface and the possibility of sensitivity enhancement. Early apoptotic cells showed an increased exposure of PS on the cell membrane caused by physiological and pathological response reactions, leading to a strong interaction between the apoptotic cells and the sensor surface, which could be probed by the ECL. Using a real of early apoptotic HepG2 cell induced by resveratrol (RVL), the proposed novel strategy has demonstrated its simplicity, high sensitivity, good selectivity and high reproducibility and label-free capability which might hold a great potential for rapid detection of cell apoptosis and drug screening. The results from this approach have showed good agreement with those obtained using inverted microscope, flow cytometry(FCM) and Atomic force microscopy(AFM). The linear range for early apoptotic cells detection ranged from 500 to 1.0 × 10(6) cells mL(-1) with a detection limit of 500 cells mL(-1). The reported strategy has provided a promising platform for highly sensitive cytosensing and convenient screening of some clinically anticancer drugs.