Electrochemical Sensors Based on the Electropolymerized Natural Phenolic Antioxidants and Their Analytical Application

Abstract

The design and fabrication of novel electrochemical sensors with high analytical and operational characteristics are one of the sustainable trends in modern analytical chemistry. Polymeric film formation by the electropolymerization of suitable monomers is one of the methods of sensors fabrication. Among a wide range of the substances able to polymerize, the phenolic ones are of theoretical and practical interest. The attention is focused on the sensors based on the electropolymerized natural phenolic antioxidants and their analytical application. The typical electropolymerization reaction schemes are discussed. Phenol electropolymerization leads to insulating coverage formation. Therefore, a combination of electropolymerized natural phenolic antioxidants and carbon nanomaterials as modifiers is of special interest. Carbon nanomaterials provide conductivity and a high working surface area of the electrode, while the polymeric film properties affect the selectivity and sensitivity of the sensor response for the target analyte or the group of structurally related compounds. The possibility of guided changes in the electrochemical response for the improvement of target compounds' analytical characteristics has appeared. The analytical capabilities of sensors based on electropolymerized natural phenolic antioxidants and their future development in this field are discussed.

Keywords: antioxidants; carbon nanomaterials; electrochemical sensors; electropolymerization; natural phenolics; voltammetry.

Scheme 1

Phenol electropolymerization. Reprinted from [8] with permission from Elsevier.

Scheme 2

Aminophenol electropolymerization in acidic medium. Adapted from [17,18].

Scheme 3

Electropolymerization of 3-aminophenol in neutral and basic medium.

Figure 1

Classification of the natural phenolic antioxidants.

Scheme 4

Eugenol oxidation and hypothesized structure of polyeugenol. Adapted from [21] with permission from the American Chemical Society.

Scheme 5

Oxidation pathway of flavonoids. Reprinted from [30].

Scheme 6

Electropolymerization of p-coumaric acid in basic medium. Reprinted from [37] with permission from Elsevier.

Figure 2

(a) Cyclic voltammograms of 1.0 mM catechin at activated CPE in 0.1 M phosphate buffer pH 7.4. Reprinted with modification from [44] with permission from the Royal Society of Chemistry; (b) cyclic voltammograms of 1.0 mM apigenin at GCE in 1:4 methanol−phosphate buffer mixture pH 7. Reprinted with modification from [47] with permission from the Royal Society of Chemistry.

Figure 3

SEM images of curcumin drop-casted on the electrode before electropolymerization (a) and polycurcumin formed after 20 cycles of potentiodynamic electrolysis (b). Reprinted from [48] with permission from Elsevier.

Figure 4

Cyclic voltammograms of the poly(caffeic acid)/GCE in 0.05 M phosphate buffer pH 4.8 at various potential scan rates (25, 50, 75, 100, 125, 150, 175, 200, 225, 250 mV s⁻¹). Reproduced with modification from [51] with permission from the Royal Society of Chemistry.

Scheme 7

Reduction of o-quinone fragments in the natural phenol-based polymer.

Figure 5

(a) Schematic representation of the synthesis of poly(curcumin-Ni complex) and its binding to amyloid β oligomer (Aβ_1–42); (b) Nyquist plots of poly(curcumin-Ni complex) sensor after incubation in various concentrations of amyloid β oligomer solution. Reprinted from [59] with permission from Elsevier.

Figure 6

Differential pulse voltammograms of equimolar mixtures of hydroquinone and catechol at the over-oxidized polyrutin-based sensor in phosphate buffer pH 7.2. Reprinted from [53] with permission from Elsevier.

Figure 7

Poly(p-coumaric acid)-based sensor and its response towards the mixture of cadmium and lead in square-wave anodic stripping mode. Reprinted from [37] with permission from Elsevier.

Figure 8

Schematic illustration of a transient NO sensor composed of a bioresorbable substrate (copolymer of poly(l-lactic acid) and poly(trimethylene carbonate)), Au nanomembrane electrodes, and a poly(eugenol) thin film. The sensor implanted in the joint cavity of a New Zealand white rabbit allows for continuously detecting NO concentrations in vivo and transmitting the data to a user interface through a customized wireless module. Reprinted from [69].

Figure 9

Isopropylmethylphenol structure.

Figure 10

Atomic force microscopy images of polycarvacrol/Cu (a) and polythymol/Cu (b). Reprinted from [71] with permission from Elsevier.

Figure 11

NADH, dopamine, and epinephrine oxidation scheme on poly(ferulic acid)/MWCNTs/GCE. Reprinted from [34] with permission from Elsevier.

Figure 12

Differential pulse voltammograms of quercetin at the sensor based on MWCNTs and poly(gallic acid) in phosphate buffer pH 7.4. Reprinted from [32] with permission from Elsevier.

Figure 13

Typical baseline-corrected differential pulse voltammograms (a) and chronoamperograms (b) of tea on polyquercetin/MWCNTs/GCE in phosphate buffer pH 7.0. Reproduced with modification from [78] with permission from Springer Nature.

Figure 14

Schematic presentation of the polycurcumin-based sensor and its response to Hg(II), fluoride, and cyanide. Reprinted from [85] with permission from Springer Nature.

Figure 15

(a) SEM image of Au nanoparticles/poly(caffeic acid)/GCE; (b) cyclic voltammograms of 50 μM acetaminophen at bare GCE (curve a), poly(caffeic acid)/GCE (curve b), and Au nanoparticles/poly(caffeic acid)/GCE (curve c) in 0.01 M phosphate buffered saline pH 7.4. Reprinted from [89] with permission from Elsevier.

Figure 16

Schematic representation of the sensor based on the polycurcumin/gold foam decorated by molybdenum disulfide nanosheets and analytical application. Reprinted from [95] with permission from Elsevier.

Figure 17

Schematic illustration of the electrosynthesis of surface-imprinted polyscopoletin nanofilm on a gold electrode surface and its use for the detection of the target proteins. Reprinted from [99] with permission from Elsevier.

Figure 18

Schematic representation of the specific recognition of isocarbophos by a functionalized cavity of the terpolymer matrix based on poly(o-phenylenediamine-co-gallic acid-co-m-aminobenzoic acid). Reprinted from [105] with permission from Elsevier.