Sensitive Detection of Rosmarinic Acid Using Peptide-Modified Graphene Oxide Screen-Printed Carbon Electrode

Abstract

Peptides have been used as components in biological analysis and fabrication of novel sensors due to several reasons, including well-known synthesis protocols, diverse structures, and acting as highly selective substrates for enzymes. Bio-conjugation strategies can provide a simple and efficient way to convert peptide-analyte interaction information into a measurable signal, which can be further used for the manufacture of new peptide-based biosensors. This paper describes the sensitive properties of a peptide-modified graphene oxide screen-printed carbon electrode for accurate and sensitive detection of a natural polyphenol antioxidant compound, namely rosmarinic acid. Glutaraldehyde was chosen as the cross-linking agent because it is able to bind nonspecifically to the peptide. We demonstrated that the strong interaction between the immobilized peptide on the surface of the sensor and rosmarinic acid favors the addition of rosmarinic acid on the surface of the electrode, leading to an efficient preconcentration that determines a high sensitivity of the sensor for the detection of rosmarinic acid. The experimental conditions were optimized using different pH values and different amounts of peptide to modify the sensor surface, so that its analytical performances were optimal for rosmarinic acid detection. By using cyclic voltammetry (CV) as a detection method, a very low detection limit (0.0966 μM) and a vast linearity domain, ranging from 0.1 µM to 3.20 µM, were obtained. The novelty of this work is the development of a novel peptide-based sensor with improved performance characteristics for the quantification of rosmarinic acid in cosmetic products of complex composition. The FTIR method was used to validate the voltammetric method results.

Keywords: cyclic voltammetry; graphene oxide; peptide; rosmarinic acid; sensor.

Figure 1

Chemical structure of rosmarinic acid.

Figure 2

Chemical structure of peptide under study.

Figure 3

Preparation process of GO-Peptide/SPCE sensor.

Figure 4

FTIR spectra for GO/SPCE (green line) and GO-Peptide/SPCE (red line).

Figure 5

Scanning electron micrograph at different magnifications representing the active surface of GO-Peptide/SPCE: (A) 2000 times magnification; (B) 10,000 times magnification; (C) 25,000 times magnification.

Figure 5

Scanning electron micrograph at different magnifications representing the active surface of GO-Peptide/SPCE: (A) 2000 times magnification; (B) 10,000 times magnification; (C) 25,000 times magnification.

Figure 6

Influence of pH on the intensity of the anodic peak current (A). Cyclic voltammogram of GO-Peptide/SPCE immersed in 0.1 M PBS, pH = 6.5 (B).

Figure 7

Cyclic voltammograms of sensors modified with: 10 µL peptide solution, uncross-linked (black line); 10 µL peptide solution, cross-linked (red line); 20 µL peptide solution, uncross-linked (green line); 20 µL peptide solution, cross-linked (blue line). All sensors immersed in 0.1 M PBS, pH = 6.5. Scan rate: 0.05 V·s⁻¹.

Figure 8

Cyclic voltammograms of GO/SPCE (black line) and GO-Peptide/SPCE (red line) immersed in 10⁻³ M K₄[Fe(CN)₆]/K₃[Fe(CN)₆]-0.1 M PBS solution, at the scan rate of 0.05 V·s⁻¹.

Figure 9

Cyclic voltammograms of GO/SPCE (a) and GO-Peptide/SPCE (c) immersed in 10⁻³ M K₄[Fe(CN)₆]/K₃[Fe(CN)₆]-0.1 M PBS solution at pH = 6.5 recorded at scan rates between 0.05 and 0.5 V·s⁻¹. Linear dependence of Ipa and square root of scan rate in the case of GO/SPCE (b) and linear dependence of Ipa and scan rate in the case of GO-Peptide/SPCE (d).

Figure 10

Cyclic voltammograms of GO/SPCE (red line) and GO-Peptide/SPCE (black line) immersed in 10⁻³ M rosmarinic acid-0.1 M PBS solution (pH 6.5). Scan rate: 0.05 V·s⁻¹.

Figure 11

The oxidation mechanism of rosmarinic acid.

Figure 12

Cyclic voltammograms of GO/SPCE (a) and GO-Peptide/SPCE (c) immersed in 10⁻³ M rosmarinic acid-0.1 M PBS at pH = 6.5 recorded at scan rates between 0.05 and 0.5 V·s⁻¹. Linear dependence between Ipa and square root of scan rate in the case of GO/SPCE (b) and linear dependence between Ipa and scan rate in the case of GO-Peptide/SPCE (d).

Figure 13

Cyclic voltammograms recorded for GO-Peptide/SPCE with the concentration between 0.1 and 3.20 µM rosmarinic acid (a); Linear dependence between Ipa and rosmarinic acid concentration in the range 0.1–3.20 µM (b).

Figure 14

Cyclic voltammograms of GO-Peptide/SPCE immersed in solutions of (a) Apiterra anti-aging cream, (b) Sabio soothing and repairing balm, and (c) Vivanatura moisturizing mattifying cream of different concentrations. Scan rate: 0.05 V·s⁻¹.

Figure 15

FTIR Spectra for: Apiterra anti-aging cream (blue line), Sabio soothing and repairing balm (red line), and Vivanatura moisturizing mattifying cream (pink line).