Simple and label-free creatine kinase activity assay based on personal glucose meter

Abstract

We herein developed a simple and label-free method to determine the creatine kinase (CK) activity by employing the personal glucose meter (PGM) as a detection component. This method relies on the target-induced cascade enzymatic reaction (CER) promoted by the combined activities of CK and hexokinase (HK). In principle, the designed CER starts with the CK-catalyzed phosphorylation of adenosine 5’-diphosphate (ADP) into adenosine 5’-triphosphate (ATP) which can serve as a phosphate source for the subsequent HK reaction promoting the phosphorylation of the glucose molecule. In addition, the ADP produced by the HK reaction induces another cycle of CER, leading to the amplified decrease of the glucose level in the reaction solution which can be simply measured by using the PGM. With this unique principle, we successfully determined the CK activity down to 0.00294 U/mL with high specificity against different types of kinase activities. Importantly, the practical applicability of the strategy was successfully verified by reliably analyzing the CK activity included in human blood.