Oxidized 3,3′,5,5′-tetramethylbenzidine nanobelts enhance colorimetric sensing of H2O2

Herein, oxidized 3,3′,5,5′-tetramethylbenzidine (oxTMB) nanobelts were developed to enhance the colorimetric and paper-based sensing of H 2 O 2 . It was found that the minor component of Fe 2+ in Na 2 SO 4 reagent could catalyze the oxidization of TMB by H 2 O 2 into positively charged oxTMB, which was further assembled into dark blue oxTMB nanobelts via electrostatic interaction with SO 4 2− . The extinction originating from the absorption and scattering of oxTMB nanobelts was utilized to quantitatively detect H 2 O 2 with a wide linear detection range (1.0–300 μM) and a low limit of detection (0.48 μM). In addition, no coffee-ring effect was observed in the test zone of the paper-based colorimetric array, which was beneficial to judge the color by naked eye. Finally, the colorimetric method was applied to detect H 2 O 2 in contact lens care solution. This work not only proposed a new colorimetric sensing platform for H 2 O 2 , but also highlighted the minor component in the reagent might influence the experimental result.