Decoupling of Confused Complex in Oxidation of 3,3’,5,5’-Tetramethylbenzidine Enhancing Reliability of Chromogenic Bioassay

Pathway regulation of chemical reactions is an important means of precision chemistry. As an extremely important chromogenic substrate, 3,3’,5,5’-tetramethylbenzidine (TMB) generally undertakes one-electron oxidation, but the reaction product (TMBox1), a confused complex, is unstable, which significantly hampers the practical applications, such as clinic enzyme-linked immunosorbent assay (ELISA). Herein, we report that sodium dodecyl sulfate (SDS)-based micelles could promote the direct two-electron oxidation pathway of TMB into more stable TMBox2. Different to the common processes of one-electron TMB oxidation by homogeneous peroxidase (POD) or other emerging heterogeneous nanocatalysts, the confused complex consisted of TMB and TMBox1 was successfully decoupled by SDS micelles via spatial isolation and electrostatic effect. As a proof-of-concept application, glucose oxidase and SDS micelles were cascaded for glucose detection, and the selective two-electron oxidation of TMB endowed enhanced reliability and broader detection range of glucose chromogenic bioassays without any conventional strong acid termination.