Cascade Chromogenic System with Exponential Signal Amplification for Visual Colorimetric Detection of Acetone

Abstract

The signal of the traditional chromogenic systems is directly proportional to analyte concentration, leading to an unsatisfactory sensitivity. Herein, we report a cascade chromogenic system to realize exponential amplification of colorimetric signal through coupling chemical oxidation with photoinduced radical chain reaction. The chemical oxidation of o-phenylenediamine (OPD) by Fe3+ generates Fe2+ and photoactive 2,3-diaminophenazine (DAP). Under blue-light irradiation, DAP initiates the formation of holes and H2O2 that reacts with Fe2+ to hydroxyl radicals (·OH) and Fe3+ via an intersystem crossing (ISC) process. Moreover, the holes oxidize water to yield ·OH as well. The resulting ·OH and regenerated Fe3+ in turn oxidize OPD to yield more DAP, leading to a self-propagating reaction cycle that continues to proceed until all the OPD molecules are consumed, along with a distinct color change from colorless to yellow. Through the generation of the complex between DAP and acetone that limits the ISC process, and therefore quenches the colorimetric signal, the highly sensitive and selective naked-eye detection of acetone is achieved from 50 μM to 3 mM, with a limit of detection of 35 μM. Additionally, the feasibility of this colorimetric assay to detect acetone in real water samples is also demonstrated.

Label-free colorimetric detection of glutathione by autocatalytic oxidation of o-phenylenediamine based on Au3+ regulation and its application

“…1b). According to previous reports, several metal ions, such as Ce 4+ , Cu 2+ , Ag + , and Fe 3+ , have the oxidation capability to oxidate OPD, [22][23][24][25] and the generated metal nanoparticles (NPs) can catalyze the reaction between OPD and metal ions; 26 in our work, these interference metal ions barely responded to our sensing system, possibly due to the different View Article Online conditions of the sensing system, such as the absence of hydrogen peroxide, blue-light proof, low concentrations of reactants, and a short incubation time. In addition, the capability of OPD to cause the aggregation of Au NPs through NH-Au bond 27 may explain how Au NPs catalyze the oxidation reaction.…”

Advances in immunoassay‐based strategies for mycotoxin detection in food: From single‐mode immunosensors to dual‐mode immunosensors

“…According to different substrates, CM immunoassays can be classified into single CM immunosensors and multiple CM immunosensors. Generally, the common single CM substrates mainly include o ‐phenylenediamine (OPD) (Liang et al., 2020), 3,3′,5,5′‐tetramethylbenzidine (TMB) (Zhu et al., 2020), and 2,2‐diazo‐bis(3‐ethyl‐benzothiazole‐6‐sulfonic acid) diammonium salt (ABTS) (Liu, Gan, et al., 2019), which are mainly used to realize the detection of the targets with different concentrations through the depth of color. However, the single‐color variation is sometimes inconspicuous, so naked‐eye recognition is a little difficult.…”

Sweetsop-like α-Fe2O3@CoNi catalyst with superior peroxidase-like activity for sensitive and selective detection of hydroquinone

“…According to previous reports, the catalytic mechanism of nanozymes can be divided into two categories: one is the transfer of electrons between the substrate and H 2 O 2 , and the other is the active substance in the catalytic system. 38,47 In order to study the catalytic mechanism, isopropanol (IPA) was added to the solution containing TMB, H 2 O 2 , and a-Fe 2 O 3 @CoNi. As a hydroxyl radical scavenger, IPA was oen used to detect hydroxyl radicals in the oxidation process.…”