A Mix‐and‐Read Fluorescence Strategy for the Switch‐On Probing of Kinase Activity Based on an Aptameric‐Peptide/Graphene‐Oxide Platform

Protein kinase plays a vital role in regulating signal‐transduction pathways and its simple and quick detection is highly desirable because traditional kinase assays typically rely on a time‐consuming kinase‐phosphorylation process (ca. 1 h). Herein, we report a new and rapid fluorescence‐based sensing platform for probing the activity of protein kinase that is based on the super‐quenching capacity of graphene oxide (GO) nanosheets and specific recognition of the aptameric peptide (FITC‐IP₂₀). On the GO/peptide platform, the fluorescence quenching of FITC‐IP₂₀ that is adsorbed onto GO can be restored by selective binding of active protein kinase to the aptameric peptide, thereby resulting in the fast switch‐on detection of kinase activity (ca. 15 min). The feasibility of this method has been demonstrated by the sensitive measurement of the activity of cAMP‐dependent protein kinase (PKA), with a detection limit of 0.053 mU μL^?1. This assay technique was also successfully applied to the detection of kinase activation in cell lysate.