Charyyeva S.B., Kamanin S.S., Arlyapov V.A.

Tula State University, Russia, Tula

Screen-printed electrodes modified with exfoliated graphite and glucose oxidase as the basis of the biosensor

 

Nowadays, biosensors are one of the cheapest and simple kinds of devices, which allow undertaking the rapid chemical analysis with high sensitivity and selectivity. Biosensors are closely related to modern life from the diagnosis of diseases to the detection of biological agents in the environment and monitoring of industrial processes. Some characteristics of them as low cost, testability without sample preparation, availability and easiness of operating mark out biosensors from the universal analytical systems [1].

The aim of this work is development and characterization of modified screen-printed electrodes based on the glucose oxidase and exfoliated graphite for determination of glucose concentration in the samples.

As carbon material in this report, we have used exfoliated graphite (EG). EG is a low density graphitic carbon with a high temperature resistance and it has a better homogeneity of the surface than any other form of graphite, that’s why it has a preferential orientation of the basal plane. Working electrode surface was covered with nanolayers of Prussian Blue (PB), which can act as the catalyst of hydrogen peroxide reduction at 0 V vs Ag/AgCl.

The working electrode has been modified with biological material for giving biosensors selective abilities. Glucose oxidase (GOD) was used as biological material. Glucose oxidase is a homodimer with a molecular weight of about 150-180 kDa containing two tightly bound flavine adenine dinucleotide (FAD) cofactors and catalyzes the electron transfer from glucose to oxygen accompanying the production of gluconic acid and hydrogen peroxide.

The computer-drived potentiostat PalmSens EmStat (Netherlands) was used as the transducer during the measurements. The sensor response was detected by using biological material, which were located on the surface of the printed electrodes. Two different types of printed electrodes were made for analysis of exfoliated graphite effect on the characteristics of biosensors. One kind of electrodes were modified with GOD and EG immobilized in hydrogel chemically crosslinked with bovine serum albumin (BSA), while another one was modified without using EG. As crosslinking agent in biosensor preparation we have used a glutaraldehyde (GA). The amplitude of current change at the addition of substrate - glucose was the measured parameter (biosensor response).

The main characteristics of modified screen-printed electrodes based on GOD are given in table 1.

Table 1. Characteristics of the developed biosensors.

Characteristics

Biosensor based on EG + GOD

Biosensor based on GOD

Storage stability at 4ºC, days

30

14

Unit assay time, duration of single measurement, min

1 ‑ 2

1 ‑ 2

Operational stability, relative standard deviation by 15 consecutive measurements, %

2

3

Sensitivity coefficient, slope of the linear segment of the dependence of sensor response on the value of glucose, nA·mM-1

84±2

276±6

Range of determined glucose concentration, mM

0,008-4,4

0,029-1,67

Comparison of characteristics of biosensors based on developed modified screen-printed electrodes with analogues - electrodes modified with glucose oxidase and polyethyleneimine - has showed that characteristics of developed biosensor doesn't interfere to analogues [2].

Screen-printed enzyme electrodes can analyze glucose in the samples of wine products. As a reference method capillary electrophoresis was used. Testing of modified electrodes on wine samples showed that the glucose concentration values obtained using the biosensor and the reference method differs insignificantly between each other. Therefore, screen-printed electrodes modified with GOD and EG immobilized in hydrogel chemically crosslinked BSA can serve as the basis for the development of biosensors with high characteristics, which can be used for the determination of glucose in the alcohol products on industrial scale.

The study was supported by the Federal Target Program “Research and Development in Priority Directions of Progress of the Scientific and Technological Complex of Russia for the Years 2014–2020” (agreement no. 14.574.21.0062) and Russian Federation President’s grant for the state support of young Russian scientists - PhD (no. 14.Z56.14.330-MK).

Literature:

1.                 Ponamoreva O.N., Reshetilov A.N., Alferov V.A. Functioning basics of biosensors: Tula State University Publishing, 2011. – P. 157-158.

2.                 Pchelintsev N.A., Vakurov A., Millner P.A. Simultaneous deposition of Prussian Blue and creation of an electrostatic surface for rapid biosensor construction // Sensors and Actuators B: Chemical. ‒ 2009. ‒ V. 138, I. 2. ‒ P. 461-466.