Reduced Graphene Oxide and Polyaniline Nanofibers Nanocomposite for the Development of an Amperometric Glucose Biosensor

Abstract

The control of glucose concentration is a crucial factor in clinical diagnosis and the food industry. Electrochemical biosensors based on reduced graphene oxide (rGO) and conducting polymers have a high potential for practical application. A novel thermal reduction protocol of graphene oxide (GO) in the presence of malonic acid was applied for the synthesis of rGO. The rGO was characterized by scanning electron microscopy, X-ray diffraction analysis, Fourier-transform infrared spectroscopy, and Raman spectroscopy. rGO in combination with polyaniline (PANI), Nafion, and glucose oxidase (GOx) was used to develop an amperometric glucose biosensor. A graphite rod (GR) electrode premodified with a dispersion of PANI nanostructures and rGO, Nafion, and GOx was proposed as the working electrode of the biosensor. The optimal ratio of PANI and rGO in the dispersion used as a matrix for GOx immobilization was equal to 1:10. The developed glucose biosensor was characterized by a wide linear range (from 0.5 to 50 mM), low limit of detection (0.089 mM), good selectivity, reproducibility, and stability. Therefore, the developed biosensor is suitable for glucose determination in human serum. The PANI nanostructure and rGO dispersion is a promising material for the construction of electrochemical glucose biosensors.

Keywords: electrochemical glucose biosensor; polyaniline nanostructures; reduced graphene oxide.

Figure 1

Schematic representation of working GR/PANI:rGO/GOx electrode development and the reaction mechanism of the fabricated biosensor.

Figure 2

Photographs of the polymerization solution taken after (1) 5 s, (2) 1 min, (3) 1 h, and (4) 24 h from the start of the reaction.

Figure 3

Scanning electron microscope (SEM) images of PANI nanostructures (A), GO (B), rGO (C), and PANI:rGO_1:10 composite (D).

Figure 4

X-ray diffraction (XRD) patterns of graphite, GO, and rGO.

Figure 5

FTIR (A) and Raman (B) spectra of graphite, GO, and rGO.

Figure 6

Calibration plots of biosensors based on GR/PANI/GOx, GR/rGO/GOx, and GR/GOx working electrodes. Inset: linear ranges of detection. Conditions: applied potential +0.3 V; acetate-phosphate-buffered saline (A-PBS) solution (pH 6.0) with 6 mM of N-methylphenazonium methyl sulfate (PMS).

Figure 7

Calibration plots of biosensors based on GR/PANI:rGO/GOx electrodes fabricated using different ratios of PANI and rGO dispersions: 5:1, 1:1, 1:5, 1:10, and 1:15. Inset: the linear range of detection of a biosensor based on a GR/PANI:rGO_1:10/GOx electrode. Conditions: applied potential +0.3 V; A-PBS solution (pH 6.0) with 6 mM of PMS.

Figure 8

Anodic current response of the biosensor based on a GR/PANI:rGO_1:10/GOx electrode to glucose vs. time (A) and in the absence (1) and presence of (2) 0.6 mM of uric acid or (3) 0.2 mM of ascorbic acid (B). Conditions: applied potential +0.3 V; (A) A-PBS solution with 6 mM of PMS and 25 mM of glucose; (B) human serum diluted 10 times with A-PBS in the presence of 6 mM of PMS and 5 mM of glucose.

Figure 9

Current response of the biosensor based on a GR/PANI:rGO_1:10/GOx electrode to glucose, fructose, mannose, galactose, and sucrose. Conditions: applied potential +0.3 V; A-PBS solution with 6 mM of PMS; 5 mM of glucose, followed by addition 5 mM of fructose, 5 mM of mannose, 5 mM of galactose, 5 mM of sucrose, and again 5 mM of glucose.