Paper-based maskless enzymatic sensor for glucose determination combining ink and wire electrodes

Abstract

In this work we have developed an amperometric enzymatic biosensor in a paper-based platform with a mixed electrode configuration: carbon ink for the working electrode (WE) and metal wires (from a low-cost standard electronic connection) for reference (RE) and auxiliary electrodes (AE). A hydrophobic wax-defined paper area was impregnated with diluted carbon ink. Three gold-plated pins of the standard connection are employed, one for connecting the WE and the other two acting as RE and AE. The standard connection works as a clip in order to support the paper in between. As a proof-of-concept, glucose sensing was evaluated. The enzyme cocktail (glucose oxidase, horseradish peroxidase and potassium ferrocyanide as mediator of the electron transfer) was adsorbed on the surface. After drying, glucose solution was added to the paper, on the opposite side of the carbon ink. It wets RE and AE, and flows by capillarity through the paper contacting the carbon WE surface. The reduction current of ferricyanide, product of the enzymatic reaction, is measured chronoamperometrically and correlates to the concentration of glucose. Different parameters related to the bioassay were optimized, adhering the piece of paper onto a conventional screen-printed carbon electrode (SPCE). In this way, the RE and the AE of the commercial card were employed for optimizing the paper-WE. After evaluating the assay system in the hybrid paper-SPCE cell, the three-electrode system consisting of paper-WE, wire-RE and wire-AE, was employed for glucose determination, achieving a linear range between 0.3 and 15mM with good analytical features and being able of quantifying glucose in real food samples.

Trends in Paper-based Electrochemical Biosensors: From Design to Application

“…77 Gold-plated pins were employed to connect the paper-based WE as well as to act as the RE and CE. In addition, it worked as a clip to support the paper in between.…”

Staple‐Based Paper Electrochemical Platform for Celiac Disease Diagnosis

“…In the design of a three‐electrode amperometric cell, electrodes have to be separated from each other. This could be made by: i) using multiple layers, ii) direct printing (e. g., pencil‐drawn, pen‐on‐paper, or laser scribing), iii) stencil‐ or screen‐printing electrodes, or iv) using external wire electrodes ,. Moreover, thin‐ or thick‐film working electrodes (WEs) do not require the use of stencils if reference and counter electrodes (RE, CE) are located on the opposite side of the film …”

“…There are different degrees of integration between electrodes and paper and then, all the three electrodes can be included in the paper, or only some of them. In the latter case, it is usually the working electrode (RE and CE are external), but in some platforms, reference and counter electrodes are incorporated (WE is external). Alternatively, the three electrodes of the potentiostatic system can be external, as happens in this work.…”

Avidin and Glucose Oxidase‐non‐covalently Functionalized Multi‐walled Carbon Nanotubes: A New Analytical Tool for Building a Bienzymatic Glucose Biosensor

“…Amor‐Gutiérrez et al. described the use of a paper‐based platform with carbon ink, GOx, HRP and potassium ferrocyanide adsorbed on the surface. A very sensitive biosensor based on the simultaneous entrapment of GOx and HRP during the HRP‐catalyzed polymerization of noradrenaline in the presence of hydrogen peroxide was described by Liu et al.…”

“…He et al [27] proposed the use of HRP biosynthesized graphene with adjustable porous size as platform for the biocatalytic deposition of gold nanoparticles with nanomolar detection of glucose due to the synergistic effect of the porous graphene and gold nanoparticles. Amor-Gutiérrez et al [28] described the use of a paper-based platform with carbon ink, GOx, HRP and potassium ferrocyanide adsorbed on the surface. A very sensitive biosensor based on the simultaneous entrapment of GOx and HRP during the HRP-catalyzed polymerization of noradrenaline in the presence of hydrogen peroxide was described by Liu et al [29].…”