Химия и химические технологии/5. Фундаментальные проблемы

создания новых материалов и технологий.

V.A. Arlyapov, A.S. Zaitseva

Tula State university

USING THE CONDUCTING HYDROGEL BASED ON THE NEUTRAL RED AS MATRIX FOR IMMOBILIZATOPN IN THE BIOSENSOR CREATION

Screen-printed electrodes have proven promising in biosensors development due to its portability, low cost, multifunctionality and the possibility of modification. They are widely used for solving a number of practical problems, including manufacture on an industrial scale, for example, in glucometers - amperometric and optical type biosensors for the blood glucose determining.

Much attention is given to application of electroactive compounds, the mediators of electron transport, in biosensor development. Adsorption as a method of immobilization usually doesn’t provide proper sensors stability that can be reason of gradual decreasing in the analytical signal due to mediator illuviation. In addition, this method is inapplicable with water-soluble mediators. In this case, mediator fixation on the electrode surface can be ensured by covalent binding with immobilizing matrix, as the result an electroconductive hydrogel are formed.

The aim of this work is development of a biosensor based on the glucose oxidase enzyme immobilized in a conductive hydrogel formed by covalent binding of bovine serum albumin (BSA) with neutral red (NR) mediator. The conductive hydrogel was prepared by covalent cross-linking of NR with BSA between amino groups of the both components using a bifunctional reagent, glutaraldehyde (Fig. 1).

Figure 1. The covalent cross-linking of the neutral red mediator with bovine serum albumin.

Concurrently, BSA molecules bind between each other forming cross-linked structure. The biosensor working potential was determined by current-voltage dependences of the modified electrode in the presence of glucose. It was -0.4 V. In the table 1 there are the main analytical and metrological characteristics of the biosensor based on the developed modified screen-printed electrode.

Table 1. The main characteristics of the biosensor based on the developed modified screen-printed electrode

Relative standard deviation of analytical signal, %	1,6
Sensitivity coefficient, mA∙dm^3∙mol^-1	250±30
Minimum reporting level, mmol∙dm^-3	600
Maximum reporting level, mmol∙dm^-3	2,7±0,6
Limit of detection, mmol∙dm^-3	200
Long-term stability, days	12

Characteristics of the developed biosensor based on the modified screen-printed electrode was comprised with the analogs based on electropolymerized neutral red. It is shown that the developed biosensor is outperform the analogue based on electropolymerized NK in the sensitivity coefficient, that can be explained by the greater availability of the electron transport mediator for biological material, because in the case of mediator immobilization by covalent cross-linking the NR is equally spaced throughout the whole volume of the modifying mixture, while the NR electropolymerization concentrates it on the surface of the electrode, which does not allow transfer electrons from distant molecules of the enzyme. The low maximum reporting level of the detected concentrations is due to the small amount of biomaterial on the electrode surface, while higher developed biosensor limit of detection than its analogues is due to the large standard deviation of blank experiments.

Approbation of the modified screen-printed electrode was carried out on the samples of the wines. The values of glucose concentrations obtained with the developed biosensor and reference method (capillary electrophoresis) are the same taking into account confidence range, which implies that the developed enzyme sensor can be used for glucose determination in food industry and biotechnological production.

This work was supported by the grant of Russian Science Foundation (project №17-74-10078)

References:

1. Barsan M., Klincar J., Batic M., Brett C.M.A. Design and application of a flow cell for carbon-film based electrochemical enzyme biosensors, Talanta. 2007, 1983-11.

2. Ghica M, Brett C.M.A. Development of Novel Glucose and Pyruvate Biosensors at Poly (Neutral Red) Modified Carbon Film Electrode // Departamento de Quimica, Universidade de Coimbra, Coimbra, Portugal – 2006, 3004-535.

3. Pauliukaite R., Chica M., Barsan M., Brett C.M.A. Characterisation of poly(neutral red) modified carbon film electrodes application as a redox mediator for biosensors // J. Solid State Electrochem,11. – 2007, 899-11.