Recent Advances in Electroanalysis of Vitamins

Characterization, Antibacterial Evaluation and Computational Study of Synthesized 4,5-bis(Hydroxymethyl)-2-Methylpyridin-3-ol Tetraphenylborate Ion-Pair Complex

The synthesis of 4,5-bis(hydroxymethyl)-2-methylpyridin-3-ol tetraphenylborate complex in water using an anion exchange process yielded more than 76 %. The resulting white complex was obtained and characterized using various spectroscopic and analytical techniques, including ultraviolet, infrared radiation (IR), mass, elemental analysis, and nuclear magnetic resonance (NMR). The antimicrobial activity of the formed ion-associate complex was evaluated. The structural, electrical, and bonding properties of a novel pyridoxine-tetraphenylborate ion-pair complex was explored using B3LYP/6-311G(d,p) DFT simulations. Geometries designed for negative complexation energy showed thermodynamically beneficial complex formation. Reduced density gradient (RDG) analysis and non-covalent interaction (NCI) plots showed that van der Waals forces are essential to complex stability. Quantum Theory of Atoms in Molecules (QTAIM) study detected weak and moderate hydrogen bonds in the complex using bond critical point (BCP) features. These results reveal how molecules form and stabilize the pyridoxine-tetraphenylborate ion-pair complex. To know the interaction between receptors and bioactive chemicals, one must understand the mechanism of the ionic complexes formed between bioactive chemicals and/or organic molecules.

Different Aspects of the Voltammetric Detection of Vitamins: A Review

Vitamins comprise a group of organic chemical compounds that contribute significantly to the normal functioning of living organisms. Although they are biosynthesized in living organisms, some are also obtained from the diet to meet the needs of organisms, which is why they are characterized as essential chemical compounds. The lack, or low concentrations, of vitamins in the human body causes the development of metabolic dysfunctions, and for this reason their daily intake with food or as supplements, as well as the control of their levels, are necessary. The determination of vitamins is mainly accomplished by using analytical methods, such as chromatographic, spectroscopic, and spectrometric methods, while studies are carried out to develop new and faster methodologies and techniques for their analysis such as electroanalytical methods, the most common of which are voltammetry methods. In this work, a study is reported that was carried out on the determination of vitamins using both electroanalytical techniques, the common significant of which is the voltammetry technique that has been developed in recent years. Specifically, the present review presents a detailed bibliographic survey including, but not limited to, both electrode surfaces that have been modified with nanomaterials and serve as (bio)sensors as well as electrochemical detectors applied in the determination of vitamins.

A New Method for the Determination of Total Content of Vitamin C, Ascorbic and Dehydroascorbic Acid, in Food Products with the Voltammetric Technique with the Use of Tris(2-carboxyethyl)phosphine as a Reducing Reagent

The objective of the study was to develop a new method for the determination of the total content of vitamin C and dehydroascorbic acid in food, based on the technique of differential pulse voltammetry with the use of a boron-doped diamond electrode modified with mercury film. A comparison was made between the results obtained with the developed method and a proposed reference method based on high-performance liquid chromatography with spectrophotometric detection. The reduction of dehydroascorbic acid was performed with the use of tris(2-carboxyethyl)phosphine. The interference caused by the presence of tris(2-carboxyethyl)phosphine during the voltammetric determination of ascorbic acid was effectively eliminated through a reaction with N-ethylmaleimide. The conducted validation of the voltammetric method indicated that correct results of analysis of the total content of vitamin C and ascorbic acid were obtained. Analysis of the content of dehydroascorbic acid was imprecise due to the application of the differential method. The results of the analyses and the determined validation parameters of the developed method are characterised by a high degree of conformance with the results obtained with the chromatographic reference method, which indicates the equivalence of the two methods.

Separation of the overlapped vitamin B1 and B3 voltammetric peaks by means of Continuous Wavelet Transform and differentiation

Due to the indubitable role of vitamins in maintaining human health, a lot of attention has been paid to the methods and analytical procedures of their determination. Voltammetric methods are of particular interest as they do not involve complex sample preparation, however, close values of the redox potential of some vitamins may result in peak overlapping, hindering the quantitative analysis. This paper addresses the separation of overlapped reduction peak of vitamins B1 and B3 by means of Continuous Wavelet Transform (with appropriately selected mother wavelets) and differentiation of the recorded voltammograms. These numerical algorithms allowed to obtained linear, single-variable calibration functions that comply with the applied in analytical chemistry criteria regarding the correlation coefficients and the limit of detection and quantification. Their relatively simple implementation does not include any manual interpretation step; thus, these algorithms provide impartial and reproducible results. The proposed methodology has been applied in the determination of vitamins B1 and B3 in dietary supplements, providing results consistent with the declaration of the manufacturer.

Graphic abstract

Wearable and Mobile Sensors for Personalized Nutrition

While wearable and mobile chemical sensors have experienced tremendous growth over the past decade, their potential for tracking and guiding nutrition has emerged only over the past three years. Currently, guidelines from doctors and dietitians represent the most common approach for maintaining optimal nutrition status. However, such recommendations rely on population averages and do not take into account individual variability in responding to nutrients. Precision nutrition has recently emerged to address the large heterogeneity in individuals' responses to diet, by tailoring nutrition based on the specific requirements of each person. It aims at preventing and managing diseases by formulating personalized dietary interventions to individuals on the basis of their metabolic profile, background, and environmental exposure. Recent advances in digital nutrition technology, including calories-counting mobile apps and wearable motion tracking devices, lack the ability of monitoring nutrition at the molecular level. The realization of effective precision nutrition requires synergy from different sensor modalities in order to make timely reliable predictions and efficient feedback. This work reviews key opportunities and challenges toward the successful realization of effective wearable and mobile nutrition monitoring platforms. Non-invasive wearable and mobile electrochemical sensors, capable of monitoring temporal chemical variations upon the intake of food and supplements, are excellent candidates to bridge the gap between digital and biochemical analyses for a successful personalized nutrition approach. By providing timely (previously unavailable) dietary information, such wearable and mobile sensors offer the guidance necessary for supporting dietary behavior change toward a managed nutritional balance. Coupling of the rapidly emerging wearable chemical sensing devices-generating enormous dynamic analytical data-with efficient data-fusion and data-mining methods that identify patterns and make predictions is expected to revolutionize dietary decision-making toward effective precision nutrition.

Phthalocyanine Modified Electrodes in Electrochemical Analysis

Phthalocyanines are aromatic or macrocyclic organic compounds and attract great attention due to their numerous properties. They have many high-tech applications in different areas of the industry such as dyestuffs, thermal printing screens, photovoltaic solar cells, membrane catalytic reactors, semiconductor materials and gas sensors. In the last decade, electrochemical sensor studies have accelerated with the catalytic lighting. It plays a dominant role in the development and implementation of new generation sensors. The aim of this study is to review the electrochemical methods based on electrode modification with phthalocyanines and to shed light on new application areas of phthalocyanines. The focal point was based on the sensor applications of phthalocyanines in the determination of drugs, pesticides, organic materials and metals etc. by electrochemical methods. Experimental conditions and some validation parameters of the sensor applications such as metal phthalocyanine types, indicator electrodes, selectivity, working ranges, detection limits, and analytical applications were discussed. Consequently, this is the first review dealing with the applications of phthalocyanines in electrochemical sensors for the sensitive determination of analytes in a variety of matrices.

Voltammetric detection of vitamin B1 (thiamine) in neutral solution at a glassy carbon electrode via in situ pH modulation

Pretreatment of glassy carbon electrode at an appropriate negative potential provide hydroxide ion which contributes to the in situ pH modulation of the electrode for thiamine detection in neutral solution.

Cannabis sativa-derived carbon dots co-doped with N–S: highly efficient nanosensors for temperature and vitamin B12

Cannabis sativa-derived carbon dots as efficient nanosensors for temperature and vitamin B₁₂.

Fluorescent carbon dots nanosensor for label-free determination of vitamin B12 based on inner filter effect

A simple and effective fluorescent assay for the determination of vitamin B₁₂ was developed. In this study, carbon dots (CDs) were prepared by one-pot hydrothermal method and directly used as a fluorophore in the inner filter effect (IFE). Both of the maximum absorption peak of vitamin B₁₂ and excitation maxima of CDs are located at 360nm, hence, the excited light of CDs can be absorbed by vitamin B₁₂, resulting in the fluorescence reduction of CDs. And the fluorescence intensity of CDs decreases with the increasing concentration of vitamin B₁₂. This IFE-based sensing strategy shows a good linear relationship between the normalized fluorescence intensity and the concentration of vitamin B₁₂ ranging from 0 to 60μM, with a limit of detection (LOD) of 0.1μM at a signal-to-noise ratio of 3. Furthermore, this proposed approach was successfully applied to vitamin B₁₂ sensing in injections. This IFE sensing platform based on various fluorescent nanomaterials has a high promise for the detection of other biomolecules due to its inherent convenience.

Wiring Bacterial Electron Flow for Sensitive Whole-Cell Amperometric Detection of Riboflavin

A whole-cell bioelectrochemical biosensing system for amperometric detection of riboflavin was developed. A "bioelectrochemical wire" (BW) consisting of riboflavin and cytochrome C between Shewanella oneidensis MR-1 and electrode was characterized. Typically, a strong electrochemical response was observed when riboflavin (VB2) was added to reinforce this BW. Impressively, the electrochemical response of riboflavin with this BW was over 200 times higher than that without bacteria. Uniquely, this electron rewiring process enabled the development of a biosensing system for amperometric detection of riboflavin. Remarkably, this amperometric method showed high sensitivity (LOD = 2.2 nM, S/N = 3), wide linear range (5 nM ∼ 10 μM, 3 orders of magnitude), good selectivity, and high resistance to interferences. Additionally, the developed amperometric method featured good stability and reusability. It was further applied for accurate and reliable determination of riboflavin in real conditions including food, pharmaceutical, and clinical samples without pretreatment. Both the cost-effectiveness and robustness make this whole-cell amperometric system ideal for practical applications. This work demonstrated the power of bioelectrochemical signal amplification with exoelectrogen and also provided a new idea for development of versatile whole-cell amperometric biosensors.