Colorimetric Assays for Acetylcholinesterase Activity and Inhibitor Screening Based on the Disassembly-Assembly of a Water-Soluble Polythiophene Derivative

A complex between an anionic polythiophene derivative (PT-COO-) and a cationic surfactant, myristoylcholine, has been prepared and applied to be colorimetric probe for acetylcholinesterase (AChE) assays. The complex formation process, AChE activity assay and inhibitor screening has been studied by absorption spectroscopy. It was confirmed that the introduction of myristoylcholine into PT-COO- phosphate buffer solution resulted in the disassembly of PT-COO- aggregates, and further addition of AChE into the above solution led to the reassembly of PT-COO- due to the catalyzed hydrolysis of myristoylcholine and the collapse of the complex. The colorimetric assay for AChE can be readily realized with the concentration of AChE as low as 0.2 U/mL. The results also demonstrate that the colorimetric approach can be applied for screening inhibitors of AChE.