Following Glucose Oxidase Activity by Chemiluminescence and Chemiluminescence Resonance Energy Transfer (CRET) Processes Involving Enzyme-DNAzyme Conjugates

Angelica Niazov,Itamar Willner,Ronit Freeman,Julia Girsh

doi:10.3390/s111110388

Abstract

A hybrid consisting of glucose oxidase-functionalized with hemin/G-quadruplex units is used for the chemiluminescence detection of glucose. The glucose oxidase-mediated oxidation of glucose yields gluconic acid and H2O2. The latter in the presence of luminol acts as substrate for the hemin/G-quadruplex-catalyzed generation of chemiluminescence. The glucose oxidase/hemin G-quadruplex hybrid was immobilized on CdSe/ZnS quantum dots (QDs). The light generated by the hybrid, in the presence of glucose, activated a chemiluminescence resonance energy transfer process to the QDs, resulting in the luminescence of the QDs. The intensities of the luminescence of the QDs at different concentrations of glucose provided an optical means to detect glucose.

Highlights

The hemin/G-quadruplex horseradish peroxidase (HRP)-mimicking DNAzyme attracts substantial research effort as catalytic [1] or electrocatalytic label [2,3] for the amplification of biorecognition events
We demonstrate that the chemiluminescence, generated by the HRP-mimicking DNAzyme, in the presence of luminol and the Glucose Oxidase (GOx)-generated H2O2, stimulate the chemiluminescence resonance energy transfer (CRET) to CdSe/ZnS quantum dots (QDs) and triggers on the luminescence of the QDs
We examined the possibility of coupling the DNAzyme-GOx conjugate to CdSe/ZnS QDs with a goal that the generated chemiluminescence light will stimulate a chemiluminescence resonance energy transfer (CRET) process to the QDs and will trigger-on the luminescence of the QDs

Summary

Introduction

The hemin/G-quadruplex horseradish peroxidase (HRP)-mimicking DNAzyme attracts substantial research effort as catalytic [1] or electrocatalytic label [2,3] for the amplification of biorecognition events. The HRP-mimicking DNAzyme has been used as a catalyst for the colorimetric or chemiluminescence detection of DNA [4,5,6], aptamer substrate complexes [7,8,9,10], and for the analysis. The hemin/G-quadruplex nanostructure was found to act as an electron transfer quencher of the luminescence of the quantum dots, and the system was used to sense DNA or aptamer-substrate complexes [25], or to follow the telomerization process [26]. The hemin/G-quadruplex was conjugated to quantum dots and used to develop chemiluminescence resonance energy transfer (CRET)-based DNA sensors [27] or aptasensors [28]. H2O2/luminol, provided the energy needed to excite the quantum dots This enabled the development of QDs-based chemiluminescent DNA or aptamer-substrate sensors with no external illumination. This process was used to probe the catalytic activity of glucose oxidase

Chemicals

Synthesis of the GOx–DNAzyme Conjugate

Chemiluminescent Analysis of Glucose by the GOx–DNAzyme Conjugates

Results and Discussion

Conclusions