Determination of ferulic acid in the presence of butylated hydroxytoluene as two phenolic antioxidants using a highly conductive food nanostructure electrochemical sensor

Graphene-Based Electrochemical Sensing Platform for Rapid and Selective Ferulic Acid Quantification

Due to the multitude of physiological functions, ferulic acid (FA) has a wide range of applications in the food, cosmetic, and pharmaceutical industries. Thus, the development of rapid, sensitive, and selective detection tools for its assay is of great interest. This study reports a new electroanalytical approach for the quantification of ferulic acid in commercial pharmaceutical samples using a sulphur-doped graphene-based electrochemical sensing platform. The few-layer graphene material (exf-SGR) was prepared by the electrochemical oxidation of graphite, at a low applied bias (5 V), in an inorganic salt mixture of Na2S2O3/(NH4)2SO4 (0.3 M each). According to the morpho-structural characterization of the material, it appears to have a high heteroatom doping degree, as proved by the presence of sulphur lines in the XRD pattern, and the C/S ratio was determined by XPS investigations to be 11.57. The electrochemical performances of a glassy carbon electrode modified with the exf-SGR toward FA detection were tested by cyclic voltammetry in both standard laboratory solutions and real sample analysis. The developed modified electrode showed a low limit of detection (30.3 nM) and excellent stability and reproducibility, proving its potential applicability as a viable solution in FA qualitative and quantitative analysis.

Voltammetric Investigation of Ferulic Acid at Disposable Pencil Graphite Electrode

Ferulic acid (FA), a monohydroxycinnamic acid, is an antioxidant with multiple beneficial effects on human health, presenting also importance in the food and cosmetics industry. Its electrochemical behavior was investigated at the disposable and cost-effective pencil graphite electrode (PGE). Cyclic voltammetry emphasized its pH-dependent, diffusion-controlled oxidation. Using the optimized conditions (HB type PGE, Britton Robinson buffer pH 4.56) differential pulse and square-wave voltammetric techniques were applied for its quantitative determination in the range 4.00 × 10-7-1.00 × 10-3 mol/L FA. The developed methods were employed for the rapid and simple assessment of the FA content from a commercially available powder designed for cosmetic use.

Nanomaterials-based electrochemical sensors for the detection of natural antioxidants in food and biological samples: research progress

Antioxidants are healthy substances that are beneficial to the human body and exist mainly in natural and synthetic forms. Among many kinds of antioxidants, the natural antioxidants have great applications in many fields such as food chemistry, medical care, and clinical application. In recent years, many efforts have been made for the determination of natural antioxidants. Nano-electrochemical sensors combining electrochemistry and nanotechnology have been widely used in the determination of natural antioxidants due to their unique advantages. Therefore, a large number of nanomaterials such as metal oxide, carbon materials, and conducting polymer have attracted much attention in the field of electrochemical sensors due to their good catalytic effect and stable performance. This review mainly introduces the construction of electrochemical sensors based on different nanomaterials, such as metallic nanomaterials, metal oxide nanomaterials, carbon nanomaterials, metal-organic frameworks, polymer nanomaterials, and other nanocomposites, and their application to the detection of natural antioxidants, including ascorbic acid, phenolic acids, flavonoid, tryptophan, citric acid, and other natural antioxidants. In the end, the limitations of the existing nano-sensing technology, the latest development trend, and the application prospect for various natural antioxidant substances are summarized and analyzed. We expect that this review will be helpful to researchers engaged in electrochemical sensors.

Synthesis of Novel Antiviral Ferulic Acid-Eugenol and Isoeugenol Hybrids Using Various Link Reactions

To develop novel antiviral agents, some novel conjugates between ferulic acid and eugenol or isoeugenol were designed and synthesized by the link reaction. The antiviral activities of compounds were evaluated using the half leaf dead spot method. Bioassay results showed acceptable antiviral activities of some conjugates against the tobacco mosaic virus (TMV) and cucumber mosaic virus (CMV). Compounds A9, A10, E1, and E4 showed remarkable curative, protective, and inactivating effects on TMV and CMV at 500 μg mL^-1. Notably, these compounds exhibited excellent protective effects on TMV and CMV. The EC₅₀ values of compounds A9, A10, E1, and E4 against TMV were 180.5, 169.5, 211.4, and 135.5 μg mL^-1, respectively, and those against CMV were 210.5, 239.1, 218.4, and 178.6 μg mL^-1, respectively, which were superior to those of ferulic acid (471.5 and 489.2 μg mL^-1), eugenol (456.3 and 463.2 μg mL^-1), isoeugenol (478.4 and 487.5 μg mL^-1), and ningnanmycin (246.5 and 286.6 μg mL^-1). Then, the antiviral mechanisms of compound E4 were investigated by determining defensive enzyme activities and multi-omics analysis. The results indicated that compound E4 resisted the virus infection by enhancing defensive responses via inducing the accumulation of secondary metabolites from the phenylpropanoid biosynthesis pathway in tobacco.

Food additives: From functions to analytical methods

Food additives refer to all kinds of trace substances used in food or food processing to preserve flavor or enhance food taste, appearance, or other qualities. At present, artificial synthetic food additives have gradually replaced the natural food additives and many problems related to food additives, involving the abuse of food additives, excessive additives or even toxic additives. Obviously, food additives can bring people great sensory enjoyment and commercial convenience, but they may also cause potential risks to human health. So, it is of high significance to conduct quantitative analysis on the content of food additives. According to their functions and the regulatory requirements of food additives, this review starts from the classification and structures of various food additives involving colorants, preservatives, antioxidants, sweeteners, emulsifiers, stabilizers, thickeners, gelling agents. It then summarizes and discusses analytical methods for quantification of food additives including modern immunoassays and other biotechnological methods. The proposed review aspires to fill in the knowledge gap of food additives between academia and industry by covering all kinds of analytical methods for quantifying food additives.

Preparation of Graphene Oxide-Embedded Hydrogel as a Novel Sensor Platform for Antioxidant Activity Evaluation of Scutellaria baicalensis

Antioxidation is very important in medicine and food. The current evaluation technologies often have many shortcomings. In this work, an improved electrochemical sensing platform for the evaluation of antioxidant activity has been proposed. A hydrogel was prepared based on graphene oxide, zinc ions, and chitosan. Zinc ions play the role of crosslinking agents in hydrogels. The structure of chitosan can be destroyed by injecting hydrogen peroxide into the hydrogel, and the free zinc ions can diffuse to the surface of the electrode to participate in the electrochemical reaction. This electrochemical sensor can evaluate the antioxidant activity by comparing the current difference of zinc reduction before and after adding the antioxidant. With the help of graphene oxide, this hydrogel can greatly enhance the sensing effect. We conducted tests on 10 real samples. This proposed electrochemical platform has been successfully applied for evaluating the antioxidant activity of Scutellaria baicalensis, and the results were compared to those obtained from the 2,2-diphenyl-1-picrylhydrazyl-based traditional analysis technique.

Development of a Novel Electrochemical Biosensor Based on Carbon Nanofibers-Gold Nanoparticles-Tyrosinase for the Detection of Ferulic Acid in Cosmetics

The present paper deals with the electrochemical behavior of three types of sensors based on modified screen-printed electrodes (SPEs): a sensor based on carbon nanofibers (CNF/SPE), a sensor based on nanofibers of carbon modified with gold nanoparticles (CNF-GNP/SPE) and a biosensor based on nanofibers of carbon modified with gold nanoparticles and tyrosinase (CNF-GNP-Ty/SPE). To prepare the biosensor, the tyrosinase (Ty) was immobilized on the surface of the electrode already modified with carbon nanofibers and gold nanoparticles, by the drop-and-dry technique. The electrochemical properties of the three electrodes were studied by cyclic voltammetry in electroactive solutions, and the position and shape of the active redox peaks are according to the nature of the materials modifying the electrodes. In the case of ferulic acid, a series of characteristic peaks were observed, the processes being more intense for the biosensor, with the higher sensitivity and selectivity being due to the immobilization of tyrosinase, a specific enzyme for phenolic compounds. The calibration curve was subsequently created using CNF-GNP-Ty/SPE in ferulic acid solutions of various concentrations in the range 0.1-129.6 μM. This new biosensor allowed low values of the detection threshold and quantification limit, 2.89 × 10-9 mol·L-1 and 9.64 × 10-9 mol·L-1, respectively, which shows that the electroanalytical method is feasible for quantifying ferulic acid in real samples. The ferulic acid was quantitatively determined in three cosmetic products by means of the CNF-GNP-Ty/SPE biosensor. The results obtained were validated by means of the spectrometric method in the infrared range, the differences between the values of the ferulic acid concentrations obtained by the two methods being under 5%.

Biosensors and Sensing Systems for Rapid Analysis of Phenolic Compounds from Plants: A Comprehensive Review

Phenolic compounds are secondary metabolites frequently found in plants that exhibit many different effects on human health. Because of the relevant bioactivity, their identification and quantification in agro-food matrices as well as in biological samples are a fundamental issue in the field of quality control of food and food supplements, and clinical analysis. In this review, a critical selection of sensors and biosensors for rapid and selective detection of phenolic compounds is discussed. Sensors based on electrochemistry, photoelectrochemistry, fluorescence, and colorimetry are discussed including devices with or without specific recognition elements, such as biomolecules, enzymes and molecularly imprinted materials. Systems that have been tested on real matrices are prevalently considered but also techniques that show potential development in the field.