Sensitive cell apoptosis assay based on caspase-3 activity detection with graphene oxide-assisted electrochemical signal amplification

This paper reports a novel approach for the simple assays of cell apoptosis using electrochemical technique. In this study, caspase-3 activity, which was detected with differential plus voltammetry (DPV) as an alternative to conventional spectrometry approach, was employed as an indicator of cell apoptosis and, while an acetylated peptide Ac-GGHDEVDHGGGC was used as the blocked substrate. In the presence of casepase-3, the hydrolysis of blocked peptide might release active amine groups, which could covalently conjugate with graphene oxide. Therefore, electroactive methylene blue molecules could be further attached to the electrode surface through π-π stacking and electrostatic interactions. Using this proposed new method, a very sensitive detection of caspase-3 could be achieved with a low detection limit of 0.06. pg/mL, and a new method for sensitive detection of cell apoptosis was developed. Moreover, we have successfully used this new method to detect cell apoptosis with human pulmonary carcinoma A549 cell after apoptosis inducing.