A colorimetric assay for acetylcholinesterase activity and inhibitor screening based on the thiocholine–induced inhibition of the oxidative power of MnO2 nanosheets on 3,3′,5,5′–tetramethylbenzidine

• Published in: Mikrochimica acta (1966) 2018-10, Vol.185 (10), p.1-8, Article 446
• Main Authors: Sun, Yuan, Tan, Haonan, Li, Yinhuan
• Format: Article
• Language: English
• Subjects: Analytical Chemistry; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Colorimetry; Hydrogen peroxide; Manganese dioxide; Microengineering; Nanochemistry; Nanosheets; Nanotechnology; Original Paper; Substrates
• ISSN: 0026-3672; 1436-5073
• DOI: 10.1007/s00604-018-2974-4

The authors describe a colorimetric method for the determination of the activity of acetylcholinesterase (AChE). Manganese dioxide (MnO 2 ) nanosheets directly reacts with 3,3′,5,5′–tetramethylbenzidine (TMB) in the absence of hydrogen peroxide (H 2 O 2 ). This leads to the formation of a blue product (oxTMB) with an absorption peak at 652 nm. If AChE hydrolyzes its substrate acetylthiocholine chloride, thiocholine is formed which blocks the oxidative power of the MnO 2 nanosheets. Hence, oxTMB will not be formed. The decreased absorbance is directly related to the AChE activity in the 0.01–1.0 mU·mL −1 range. The detection limit is 0.01 mU·mL −1 and the relative standard deviation is 1.2% (for n  = 11 at 0.5 mU·mL −1 ). The method was also applied to screen for inhibitors of AChE. Graphical abstract Based on the oxidizing properties of manganese dioxide nanosheets (MnO 2 nanosheets), we report a colorimetric method for determining acetylcholinesterase activity with the chromogenic substrate 3,3′,5,5′-tetramethylbenzidine (TMB).