Novel method of phosphatase detection based on cationic conjugated polymer and enzymatic substrate probe

A novel method was developed for phosphatase detection based on cationic conjugated polymer (CCP) and enzymatic substrate. The CCP associated with the fluorescein-labeled anionic adenosine triphosphate (ATP) by electrostatic attractions and fluorescence resonance energy transfer (FRET) from the CCP to the fluorescein-labeled ATP occurred. When phosphatase was added, it catalyzed the hydrolysis of phosphate groups from its substrate, ATP, and the final product adenosine was neutral, which made the CCP detached from adenosine. Then the FRET efficiency decreased. The results show that the degree of FRET efficiency decrease is related to the concentration of phosphatase. This detection method has the advantages including easy operations, real-time response, and high sensitivity. It can also sensitively assay other enzymes that promote the changes of the charge density of substrates; moreover, it provides a promising application in drug screening based on the inhibition of enzymatic activity.