A Colorimetric Paper-Based Analytical Device for Glucose Detection Using a Ferric-based Peroxidase Nanozyme

Abstract

We propose here a paper colorimetric biosensor as an analytical device for glucose sensing (g-PAD), which was fabricated via a twostep process consisting an inkjet-printing a barrier of carbon onto filter paper to fit a working zone for the g-PAD and an immobilization of reagents including a ferric hydroxide/nitrogen doped graphene quantum dots (FN-GQDs) as peroxidase nanozyme, 3,3’,5,5’-tetramethylbenzidine (TMB) as co-substrate color indicator and glucose oxidase (GOx) as capture probe onto working zone of the g-PAD by a drop casting. Glucose sensing is conducted by adding a drop of analyte sample onto working zone. Herein, the GOx will oxidise glucose into gluconic acid and hydrogen peroxide (H2O2), and then, the FN-GQDs as peroxidase nanozyme, will catalyse for the reaction of H2O2 and TMB, which will convert the TMB from reduced state (TMBred) to oxidized TMB (TMBox) state as colorless to blue on the working zone. The blue intensity reflects concentration of glucose in sample, which can be recognized directly by naked eyes or measuring the Gray Intensity (GI). The developed g-PADs biosensor could detect glucose in a linear range from 0.025 mM to 0.5 mM with a limit of detection of 18.75 µM. This developed g-PAD has been tested for glucose monitoring in human blood plasma sample with high accuracy.