Electrochemical Determination of Vitamin D 3 in Pharmaceutical Products by Using Boron Doped Diamond Electrode

Electrochemical nanosensors: Revolutionizing vitamin detection

Electrochemical nanosensors offer remarkable capabilities for precise and selective vitamin detection, with transformative implications for healthcare, nutrition, and food industry quality control. Nanotechnology advancements have facilitated the creation of nanoscale sensors with customized properties, enhancing the efficacy of detecting vitamins. Materials such as gold nanoparticles, carbon nanotubes, and quantum dots have been modified to display remarkable sensitivity and specificity for distinct vitamins. Integrating these materials with electrochemical techniques enables the translation of biochemical interactions into measurable electrical signals, achieving accurate and swift detection. Real-time monitoring of vitamin levels enables health optimization and improves quality control, nutritional label accuracy and supply chain monitoring in the food industry. This review comprehensively examines the electrochemical properties of sensors for vitamin analysis, highlighting modernization in the design of sensors, restyling nanomaterial-based sensor technologies and exploring their applications in food quality control while simultaneously addressing current challenges and future directions in the development of sensors.

A critical review of electrochemical (bio)sensors for liposoluble antioxidants

Lipophilic antioxidants (LAOs) are essential for physical and mental health of all mammals. Their importance in the treatment and prevention of diseases is undeniable. Alongside water-soluble antioxidants, LAOs play a crucial role in maintaining the quality and stability of various food, cosmetic, and pharmaceutical products. Electrochemical detection methods have emerged as powerful analytical tools for identifying and quantifying a broad range of analytes. However, LAOs are often overlooked targets for electrochemical analysis. This critical review aims to explore the current advancements, limitations, and future perspectives of electrochemical detection methods for LAOs. The observed electrochemical methods in LAOs investigations are: cyclic voltammetry, differential pulse voltammetry, square wave voltammetry, electrochemical impedance spectroscopy, and square wave anodic stripping voltammetry. Additionally, electrochemical evaluation of total antioxidant capacity and activity are included for the discussions. The review provides an overview of the electrochemical (bio)sensors from 2018 to 2024 for LAOs determination of following groups: synthetic (phenolic, amine and organophosphate antioxidants), and natural (tocopherols, carotenoids, polyunsaturated fatty acids) antioxidants, including vitamins D and K, coenzyme Q, which are not directly associated to the antioxidant group, but also possess antioxidant activity. The general preferences of medium selection and practical aspects of the sample preparation strategy are included.

Selective dual sensing strategy for free and vitamin D3 micelles in food samples based on S,N-GQDs photoinduced electron transfer

A reliable nanotechnological sensing strategy, based on an S,N-co-doped graphene quantum dot (GQD) platform, has been developed to distinctly detect two key variants of vitamin D3, specifically the free (VD3) and the nanoencapsulated form (VD3Ms). For this purpose, food-grade vitamin D3 micelles were self-assembled using a low-energy procedure (droplet size: 49.6 nm, polydispersity index: 0.34, ζ-potential: -33 mV, encapsulation efficiency: 90 %) with an innovative surfactant mixture (Tween 60 and quillaja saponin). Herein, four fluorescent nanoprobes were also synthesized and thoroughly characterized: S,N-co-doped GQDs, α-cyclodextrin-GQDs, β-cyclodextrin-GQDs, and γ-cyclodextrin-GQDs. The goal was to achieve a selective dual sensing strategy for free VD3 and VD3Ms by exploiting their distinctive quenching behaviors. Thus, the four nanosensors allowed the individual sensing of both targets to be performed (except α-CD-GQD for VD3Ms), but S,N-GQDs were finally selected due to selectivity and sensitivity (quantum yield, QY= 0.76) criteria. This choice led to a photoinduced electron transfer (PET) mechanism associated with static quenching, where differentiation was evidenced through a displayed 13-nm hypsochromic (blue) shift when interacting with VD3Ms. The reliability of this dual approach was demonstrated through an extensive evaluation of analytical performance characteristics. The feasibility and accuracy were proven in commercial food preparations and nutritional supplements containing declared nanoencapsulated and raw VD3, whose results were validated by a paired Student's t-test comparison with a UV-Vis method. To the best of our knowledge, this represents the first non-destructive analytical approach addressing the groundbreaking foodomic trend to distinctly detect different bioactive forms of vitamin D3, while also preserving their native nanostructures as a chemical challenge, thus providing reliable information about their final stability and bioavailability.

Lemon extract supported green synthesis of bimetallic CuO/Ag nanoporous materials for sensitive detection of vitamin D3

In modern era, deficiency of Vitamin D3 is predominantly due to limited exposure to sunlight and UV radiation resulting from indoor lifestyles. Several studies have revealed that vitamin D deficiency can lead to chronic vascular inflammation, diabetes mellitus, hypertension, congestive left ventricular hypertrophy, and heart failure. This study introduces a green synthesis of novel bimetallic nanoporous composite, CuO/Ag using lemon extract. The synthesized nanoporous material, CuO/Ag@lemon extract was characterized using several analytical techniques, including X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX). The CuO/Ag@lemon extract nanoparticles were immobilized on glassy carbon electrode (GCE) to prepare modified CuO/Ag@lemon extract-GCE interface. The electrocatalytic and electrochemical properties investigation was carried out on the modified electrode. using cyclic voltammetry (CV), differential pulse voltammetry (DPV), and amperometry for detecting of Vitamin D3. The DPV method displayed a linear response range of 0.02-22.5 µM with a detection limit of 2.62 nM, while the amperometric method showed a broader linear range of 0.25-23.25 µM with a detection limit of 2.70 nM with 82% modified electrode stability. The designed electrode exhibited a positive response to the inclusion of Vitamin D3 with electro-oxidation, reaching steady-state within 3.4 s, with 87% reproducibility within a day. The proposed method offers a rapid and sensitive platform for detection of Vitamin D3 with minimal interference from other molecules. The early diagnosis of Vitamin D3 deficiency using modified electrodes allows for early treatment, thereby preventing severe health complications.

A manganese dioxide nanoparticle-bimetallic metal organic framework composite for selective and sensitive detection of vitamin D3 in human plasma

For the first time a metal organic framework nanomaterial has been developed comprising manganese dioxide nanoparticle and iron and zinc metal ions interlinked with each other via terephthalic acid. The framework shape was identified as an elongated hexagonal nanorod (TEM) with varying functional groups (FT-IR) and diffraction patterns (XRD). The framework nanocomposite as such in aqueous acidic electrolyte solution has displayed an excellent conductivity (redox behavior) and surface excess (3.08 × 10-8 cm-2). Under the optimized conditions (0.1 M H2SO4 as electrolyte, 50 mV/s scan rate, +1.26 V (vs Ag/AgCl)), the metal organic framework coated electrode has selectively identified vitamin D3 (VD3) in the presence of various other interfering molecules and displayed excellent limit of detection (1.9 ng mL-1). The developed sensor has been applied to the determination of VD3 in extracted human plasma samples (RSD of 0.3-2.6 % and recovery of 96-102 %), and the obtained VD3 values are similar to HPLC-UV method.

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.

Development of nanoluciferase-based sensing system that can specifically detect 1α,25-dihydroxyvitamin D in living cells

Previously, we reported a FLucN-LXXLL+LBD-FLucC system that detects VDR ligands using split firefly luciferase techniques, ligand binding domain (LBD) of VDR, and LXXLL sequences that interact with LBD after VDR ligand binding. In vivo, 25-hydroxyvitamin D₃ (25(OH)D₃) and 1α,25-dihydroxyvitamin D₃ (1α,25(OH)₂D₃) act as VDR ligands that bind to VDR, and regulate bone-related gene expression. Therefore, the amount of 25(OH)D₃ and 1α,25(OH)₂D₃ are indicators of bone-related diseases such as rickets and osteoporosis. In this study, we have developed a novel LgBiT-LXXLL+LBD-SmBiT system using NanoLuc Binary Technology (NanoBiT), which has an emission intensity several times higher than that of the split-type firefly luciferase. Furthermore, by using genetic engineering techniques, we attempted to construct a novel system that can specifically detect 1α,25(OH)₂D₃. Because histidine residues at positions 305 and 397 play important roles in forming a hydrogen bond with a hydroxyl group at position C25 of 25(OH)D₃ and 1α,25(OH)₂D₃, His305 and His397 were each substituted by other amino acids. Consequently, the three mutant VDRs, H305D, H397N, and H397E were equally useful to detect 1α,25(OH)₂D₃ specifically. In addition, among the 58 variants of the LXXLL sequences, LPYEGSLLLKLLRAPVEE showed the greatest increase in luminescence upon the addition of 25(OH)D₃ or 1α,25(OH)₂D₃. Thus, our novel system using NanoBiT appear to be useful for detecting native vitamin D or its derivatives.

The development of wearable technologies and their potential for measuring nutrient intake: Towards precision nutrition

Appropriate food intake and nutritional status are crucial for the maintenance of health and disease prevention. Conventional dietary assessment is mainly based on comparisons of nutrient intakes with reference intakes, failing to meet the needs of personalised nutritional guidance based on individual nutritional status. Given their capability of providing insights into health information non-invasively in real time, wearable technologies offer great opportunities for nutrition monitoring. Nutrient metabolic profiles can be monitored immediately and continuously which could potentially offer the possibility for the tracking and guiding of nutrient intake. Here, we review and highlight the recent advances in wearable sensors from the perspective of sensing technologies for nutrient detection in biofluids. The integration of biosensors with wearable devices serves as an ideal platform for the analysis of biofluids including sweat, saliva and tears. The wearable sensing systems applied to the analysis of typical nutrients and important metabolites are demonstrated in terms of carbohydrates, proteins, lipids, vitamins, minerals and others. Taking advantage of their high flexibility and lightweight, wearable sensors have been widely developed for the in situ quantitative detection of metabolic biomarkers. The technical principles, detection methods and applications are summarised. The challenges and future perspectives for wearable nutrition monitoring devices are discussed including the need to better determine relationships among nutrient metabolic profile, nutrient intake and food intake. With the development of materials, sensing techniques and manufacturing processes, wearable technologies are paving the way towards personalised precision nutrition, although there is still a long way to go before they can be utilised for practical clinical applications. Joint research efforts between nutrition scientists, doctors, engineers and sensor researchers are essential to further accelerate the realisation of reliable and practical wearable nutrition monitoring platforms.

Comparison of Validation Parameters for the Determination of Vitamin D3 in Commercial Pharmaceutical Products Using Traditional and Greener HPTLC Methods

Several analytical methods are documented for the estimation of vitamin D3 (VD3) in pharmaceuticals, food supplements, nutritional supplements, and biological samples. However, greener analytical methods for VD3 analysis are scarce in the literature. As a consequence, attempts were made to design and validate a greener “high-performance thin-layer chromatography (HPTLC)” method for VD3 estimation in commercial pharmaceutical products, as compared to the traditional HPTLC method. The greenness indices of both approaches were predicted by utilizing the “Analytical GREENness (AGREE)” method. Both traditional and greener analytical methods were linear for VD3 estimation in the 50–600 ng band−1 and 25–1200 ng band−1 ranges, respectively. The greener HPTLC strategy outperformed the traditional HPTLC strategy for VD3 estimation in terms of sensitivity, accuracy, precision, and robustness. For VD3 estimation in commercial tablets A–D, the greener analytical strategy was better in terms of VD3 assay over the traditional analytical strategy. The AGREE index of the traditional and greener analytical strategies was estimated to be 0.47 and 0.87, respectively. The AGREE analytical outcomes suggested that the greener analytical strategy had a superior greener profile to the traditional analytical strategy. The greener HPTLC strategy was regarded as superior to the traditional HPTLC methodology based on a variety of validation factors and pharmaceutical assays.

High-Performance, Nitrogen-Doped, Carbon-Nanotube-Based Electrochemical Sensor For Vitamin D3 Detection

With the fast changing lifestyle, vitamin D deficiency is becoming extremely common. Therefore, development of economical, efficient, and fast sensors for vitamin D is the need of the hour. Carbon-based nanomaterials are extensively explored in sensing of variety of biomolecules. In the present study, an antibody-free, highly sensitive, carbon-nanotube-based, highly responsive vitamin D3 sensor is reported. Nitrogen-doped carbon nanotubes are utilized to overcome the limiting factor of hydrophobic character of pure carbon. The synthesized N-doped CNTs showed a specific surface area of 24 m²/g. The surface charges of vitamin D3 and the vitamin D3/NCNT complex are found to be -20 and -6.4 mV, respectively, by zeta potential measurements. The sensor is able to deliver high performance in the concentration range of 0-10 nM, with a limit of detection of 16 pM. The response study indicated the sensitivity value as 0.000495 mA/cm² nM. The sensor is also able to show a higher selectivity toward vitamin D3 in comparison to other biomolecules. The long-term stability, reproducibility, good linear range, and ultralow detection capability of the sensor are also reported.

Voltammetry of 7-dehydrocholesterol as a new and useful tool for Smith-Lemli-Opitz syndrome diagnosis

7-Dehydrocholesterol is an essential biomarker of Smith-Lemli-Opitz syndrome, a congenital autosomal recessive disorder. This study shows for the first time that electrochemical oxidation of 7-dehydrocholesterol can be used for its voltammetric determination. Two classes of supporting electrolytes in acetonitrile and a mixture of acetonitrile-water were used: inorganic acids known to promote structural changes of steroids and indifferent electrolytes. Oxidation of 7-dehydrocholesterol at ca +0.8 V (vs. Ag/AgNO₃ in acetonitrile) in 0.1 mol L^-1 NaClO₄ in acetonitrile is useful for its voltammetric detection using common bare electrode materials. Detection limits for 7-dehydrocholesterol lie in the low micromolar range for all the working electrodes, including boron-doped diamond (0.4 μmol L^-1) and disposable thin-film platinum electrodes (0.5 μmol L^-1), which are advantageous because of the low volumes of studied solutions. After Bligh-Dyer extraction, quantification of 7-dehydrocholesterol concentration (boron-doped diamond) or concentration range (thin-film platinum) is easily attainable in artificial serum. The mere knowledge of the concentration range provides clinically valuable information, as 7-dehydrocholesterol levels are employed for SLOS diagnosis as a binary criterion (elevated, tens to hundreds μmol L^-1 in symptomatic/non-elevated, typically bellow 1 μmol L^-1 in healthy individuals in plasma). Moreover, it is shown that 7-dehydrocholesterol (provitamin D₃) and cholecalciferol (vitamin D₃) can be oxidized in 0.1 mol L^-1 HClO₄ in acetonitrile. Under these conditions, their voltammetric response changes dramatically, and their oxidation potential difference transiently increases from 0.08 V to 0.25 V, which should facilitate their simultaneous voltammetric determination. This work constitutes a foundation for a reliable and straightforward method for Smith-Lemli-Opitz syndrome diagnosis and monitoring 7-dehydrocholesterol's biotransformation to cholecalciferol.

Antioxidant Determination with the Use of Carbon-Based Electrodes

Antioxidants are compounds that prevent or delay the oxidation process, acting at a much smaller concentration, in comparison to that of the preserved substrate. Primary antioxidants act as scavenging or chain breaking antioxidants, delaying initiation or interrupting propagation step. Secondary antioxidants quench singlet oxygen, decompose peroxides in non-radical species, chelate prooxidative metal ions, inhibit oxidative enzymes. Based on antioxidants’ reactivity, four lines of defense have been described: Preventative antioxidants, radical scavengers, repair antioxidants, and antioxidants relying on adaptation mechanisms. Carbon-based electrodes are largely employed in electroanalysis given their special features, that encompass large surface area, high electroconductivity, chemical stability, nanostructuring possibilities, facility of manufacturing at low cost, and easiness of surface modification. Largely employed methods encompass voltammetry, amperometry, biamperometry and potentiometry. Determination of key endogenous and exogenous individual antioxidants, as well as of antioxidant activity and its main contributors relied on unmodified or modified carbon electrodes, whose analytical parameters are detailed. Recent advances based on modifications with carbon-nanotubes or the use of hybrid nanocomposite materials are described. Large effective surface area, increased mass transport, electrocatalytical effects, improved sensitivity, and low detection limits in the nanomolar range were reported, with applications validated in complex media such as foodstuffs and biological samples.