Sensitive Detection Of Ascorbic Acid Research Articles

MOF-derived high-density carbon nanotubes “tentacle” with boosting electrocatalytic activity for detecting ascorbic acid

Accurate detection of ascorbic acid (AA) plays a significant role in food and human physiological processes. Herein, a three-dimensional flexible leaf-like nitrogen-doped hierarchical carbon nanoarrays with high-density carbon nanotube “tentacle” architecture (NC/CNT-Co), which possesses high specific surface area, plenty of active defect sites, and various pore size distributions, was synthesized by the pyrolysis of zeolitic imidazolate framework (ZIF(Co)), while g-C3N4 acted as carbon source and heteroatom doping agent. Benefiting from its unique structure and surface properties, a selective and highly sensitive AA sensor was developed using this material. Compared to powder materials, NC/CNT-Co modified CF (CF@NC/CNT-Co) which don't be extra decorated, exhibits lower detection limit (1 μM), a wider linear range (20–1400 μM), and better stability, showing higher performance in electrocatalysis and detection of AA. Furthermore, CF@NC/CNT-Co also demonstrates high resistance to interference and fouling in AA detection. Particularly, the prepared CF@NC/CNT-Co electrode could determine AA in beverage samples with a recovery rate of 96.3–103.5 %. Therefore, the three-dimensional NC/CNT-Co hierarchical structure can be provided as an original electrode nanomaterial suitable for the selective and sensitive detection of AA, with a wide range of practical applications from food analysis to the pharmaceutical industry.

A Novel Electrochemical Sensor Based on Pd Confined Mesoporous Carbon Hollow Nanospheres for the Sensitive Detection of Ascorbic Acid, Dopamine, and Uric Acid.

In this study, we designed a novel electrochemical sensor by modifying a glass carbon electrode (GCE) with Pd confined mesoporous carbon hollow nanospheres (Pd/MCHS) for the simultaneous detection of ascorbic acid (AA), dopamine (DA), and uric acid (UA). The structure and morphological characteristics of the Pd/MCHS nanocomposite and the Pd/MCHS/GCE sensor are comprehensively examined using SEM, TEM, XRD and EDX. The electrochemical properties of the prepared sensor are investigated through CV and DPV, which reveal three resolved oxidation peaks for AA, DA, and UA, thereby verifying the simultaneous detection of the three analytes. Benefiting from its tailorable properties, the Pd/MCHS nanocomposite provides a large surface area, rapid electron transfer ability, good catalytic activity, and high conductivity with good electrochemical behavior for the determination of AA, DA, and UA. Under optimized conditions, the Pd/MCHS/GCE sensor exhibited a linear response in the concentration ranges of 300-9000, 2-50, and 20-500 µM for AA, DA, and UA, respectively. The corresponding limit of detection (LOD) values were determined to be 51.03, 0.14, and 4.96 µM, respectively. Moreover, the Pd/MCHS/GCE sensor demonstrated outstanding selectivity, reproducibility, and stability. The recovery percentages of AA, DA, and UA in real samples, including a vitamin C tablet, DA injection, and human urine, range from 99.8-110.9%, 99.04-100.45%, and 98.80-100.49%, respectively. Overall, the proposed sensor can serve as a useful reference for the construction of a high-performance electrochemical sensing platform.

Mn2+-Mediated Modulation of PfAgo Activity for Biosensing.

Argonaute (Ago) as a powerful enzyme has provided new insights into biosensing due to its programmability, high sensitivity, and user-friendly operation. However, current strategies mainly rely on phosphorylated guide DNA to modulate the cleavage activity of Ago, which is limited in versatility and simplicity. Herein, the authors report the Mn2+-enhanced cleavage activity of Ago and employ Mn-ions with variable valence to regulate the activity of Pyrococcus furiosus Ago (PfAgo) for biosensing applications. The conversion of Mn ions with different valence states through MnO2 nanoflowers enables the sensitive detection of ascorbic acid, alkaline phosphatase, and arsenic with limits of detection of 2.5 nmol L-1, 0.009 U L-1, and 0.4 ng mL-1, respectively. A PfAgo-based immunoassay is further developed that allows for the detection of diverse targets, thus providing a promising toolbox to broaden PfAgo-based sensors into versatile bioanalytical and biomedical applications.

Simultaneous and sensitive detection of ascorbic acid and uric acid using a novel MnTMPyP/LaTa2O7 nanocomposite modified glassy carbon electrode

A novel nanocomposite MnTMPyP/LaTa2O7 was synthesized via intercalation of [5, 10, 15, 20-tetrakis (N-methylpyridinium-4-yl) porphyrinato manganese (III) (MnTMPyP) into the laminar structure of RbLaTa2O7 using an ion exchange method. An electrochemical sensor utilizing a MnTMPyP/LaTa2O7 modified glassy carbon electrode (GCE) was employed for the simultaneous detection of ascorbic acid (AA) and uric acid (UA). X-ray diffractometry, Fourier infrared spectroscopy, and transmission electron microscopy were utilized to characterize the structure in this experiment. Differential pulse voltammetry (DPV), electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV) were employed to analyze the electrochemical properties. The MnTMPyP/LaTa2O7/GCE demonstrated a larger electrochemically active area (0.106 cm2), lower charge transfer resistance (43.1 Ω), and enhanced catalytic activity compared to single-component modified electrodes (RbLaTa2O7/GCE, bare/GCE). The detection limits, within the concentration ranges of 1.25–40.41 μM for AA and 0.62–11.81 μM for UA (S/N = 3), were estimated to be 0.37 μM and 0.44 μM, respectively. MnTMPyP/LaTa2O7/GCE also exhibits excellent stability, reproducibility, and anti-interference compared to previous literatures. Furthermore, the performance of MnTMPyP/LaTa2O7/GCE was demonstrated in real urine samples, achieving recoveries between 98.7 % and 103.5 %. The ion exchange provides a simpler method for the preparation of multifunctional electrochemical sensing.

Highly sensitive colorimetric sensing for ascorbic acid utilizing Co3O4@MnO2 hollow nanocubes as oxidase mimic

The development of oxidase mimic with favorable catalytic activity is of great significance for the rapid and convenient detection of ascorbic acid (AA). Herein, in this work, a synergistic regulation strategy of heterogeneous interface and hollow structure is proposed to effectively solve the problem of limited active sites obtained with Co3O4. The charge rearrangement at heterointerface could improve the catalytic activity of oxidase mimic. Moreover, the hollow nanocubes structure could increase specific surface area and provide rich active sites. As a result, the target material possesses enhanced oxidase-like catalytic activity and desirable stability compared to bare Co3O4 and MnO2, which also catalyze the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) to form a blue product (ox-TMB) even without hydrogen peroxide. Ox-TMB is reduced to TMB owing to the strong reducibility of AA, which represents a decrease in absorbance at 652 nm and a colorless solution. Moreover, an efficient biosensing method for the detection of AA is developed. The relative absorbance (∆A) of the sensing platform is linearly related to the concentration of AA in the range of 0–200 μM, and the detection limit is 0.11 μM. This work provides a novel method for the rapid, cost-effective and sensitive detection of AA, and possesses a wide range of potential application value.

Blue emission-dominated NaYbF4@NaYF4:2%Ho@NaYF4 upconversion nanoparticles for detecting ascorbic acid.

The blue emission-dominated NaYbF4@NaYF4:2%Ho@NaYF4 (CSS) upconversion nanoparticles (UCNPs) were designed to detect ascorbic acid (AA). The blue emission of CSS was increased, ∼34 and ∼8 times higher than that of NaYF4:2%Ho@NaYbF4@NaYF4 (CSS (I)) and NaYbF4@NaYF4:20%Yb,2%Ho@ NaYF4 (CSS (II)), respectively. The dominant blue emission of CSS might be attributed to three aspects: (1) the protected NaYbF4 core for high near-infrared absorption, (2) the spatial separation of Yb3+ and Ho3+ preventing back energy transfer, and (3) their inert shell inhibiting surface quenching. It is worth noting that the fluorescence resonance energy transfer (FRET) of the CSS (donor) to MnO2 nanosheets (acceptor) was developed to trace AA. The detection limit is 0.75 μM and the detection range is 0.5-100 μM. In summary, our work not only explored the blue emission mechanism of Ho3+, but also constructed a CSS/MnO2-based nanosensing platform for the rapid and sensitive detection of AA. The blue emission of Ho3+ has promising applications in the field of sensing and detection.

N/S-GQDs/KMnO4 hybrid as a colorimetric and fluorescent dual-signal readout probe for sensitive and selective detection of ascorbic acid

A nitrogen and sulfur co-doped graphene quantum dots (N/S-GQDs) and permanganate was employed to prepare a N/S-GQDs/KMnO4 dual-signal readout colorimetric and fluorescent probe for sensitive detection of ascorbic acid (AA). In the detection system, the addition of KMnO4 quenched significantly the fluorescence (FL) of N/S-GQDs, meanwhile, the transparent aqueous dispersion of N/S-GQDs changed into yellow–brown with new absorption peak (maximum absorption at 338 nm). Interestingly, introduction of AA into the N/S-GQDs/KMnO4 system could recover the quenched fluorescence and result in a decrease in the absorbance (at 338 nm) of the test solution in a concentration dependent manner, and hence demonstrated the potential practical use of the sensing system for AA detection. Based on various spectroscopic studies, it has been concluded that the static as well as inner filter effect was the main quenching mechanisms in the detection system. The dual-response sensor showed linear response in the concentration range between 0.01 and 30 µM with the limit of detection (LOD) of 8.3 nM and 100 nM, respectively, for the fluorescent and colorimetric detections. In addition, the proposed detection system has been successfully applied to the detection of AA in vitamin C tablets. Moreover, the proposed detection strategy is convenient and fast, prevents complex and tedious probe preparation procedure, and capable of visual detection of AA.

A 3D supramolecular framework-based electrochemical sensor for highly sensitive detection of ascorbic acid

A benzimidazole carboxylate ligand with multiple coordination sites has been designed by the aldimine condensation reaction of 2-pyridinecarboxal-dehyde and 3,4-diaminobenzoic acid, 2-(2′-pyridyl)-benzimidazole-6-carboxylic acid (H2pybimc), which solvothermally assembled with Ni2+ ions in the mixed solvents of H2O and n-propanol to generate a 3D supramolecular framework, {[Ni(Hpybimc)(NO3)(H2O)]}n (CP 1). The chemical composition and structure of CP 1 have been characterized in detail by various tools. Structural analysis demonstrates that the asymmetrical unit of CP 1 consists of one octahedral Ni2+ ion, one Hpybimc−, one NO3− and one coordinated water molecule. Adjacent Ni2+ ions are linked by Hpybimc− to form a 2D 3-connected ‘fes’-type topology, which further generates a 3D supramolecular architecture by hydrogen bonds and π···π stacking interactions. The carbon paste electrode (CPE) modified with CP 1 is fabricated (CPE 1) and applied for the electrochemical sensor of ascorbic acid (AA), which exhibits good linear correlation with AA in the concentration range of 5.0 × 10−4 to 7.3 mmol L−1 with the limit of detection (LOD) of 0.85 μmol L−1. Moreover, it has satisfactory stability, repeatability, and selectivity towards AA, which can be successfully used for the detections in real samples.

A rapid and sensitive smartphone colorimetric sensor for detection of ascorbic acid in food using the nanozyme paper-based microfluidic chip

Ascorbic acid is very important to human health because of its excellent antioxidant effect. Developing sensitive and on-site detection methods is therefore in high demand. In this work, a portable paper-based colorimetric sensor with a smartphone platform with an ultrahigh sensitivity has been designed for on-site and quantitative analysis of ascorbic acid based on AuNPs nanozyme activity. The developed excellent peroxidase-like nanozymes, could effectively catalyze the oxidation of chromogenic substrates by H2O2. Herein, the AuNPs nanozyme activity are embedded on paper pieces to construct paper-based microfluidic chips for visual detection. Meanwhile, a smartphone platform is integrated for the signal readout. Using ascorbic acid as an analyte model, the proposed paper-based analysis platform shows a reliable and sensitive detection of ascorbic acid with a low detection limit of 0.406 μmol/L. The platform also works well in various real samples. This analysis method is facile in design, showing a great application potential for on-site and mass screening of ingredients in the environment and in foods.

Oxidase-like Fe–N/C single atom nanozyme enables sensitive detection of ascorbic acid and acid phosphatase

The development of cost-effective and easy-to-use strategies for the detection of ascorbic acid (AA) and acid phosphatase (ACP) is in high demand but challenging. Thus, we report a novel colorimetric platform based on Fe–N/C single atom nanozyme with efficient oxidase mimicking activity for their highly sensitive detection. The designed Fe–N/C single atom nanozyme can directly oxidize 3,3′,5,5′-tetramethylbenzidine (TMB) to produce a blue oxidation product (oxTMB) in the absence of H2O2. In addition, L-ascorbic acid 2-phosphate can be hydrolyzed to ascorbic acid in the presence of ACP, which inhibits the oxidation reaction and results in a significant bleaching of the blue color. Based on these phenomena, a novel colorimetric assay with high catalytic activity was developed for the determination of ascorbic acid and acid phosphatase with detection limits of 0.092 μM and 0.048 U/L, respectively. Notably, this strategy was successfully applied to the determination of ACP in human serum samples and evaluate ACP inhibitors, indicating its potential as a valuable tool for clinical diagnosis and research.

Silver-Coated Gold Nanorods as Optical Probes for the Sensitive Detection of Ascorbic Acid in Tablets

Ascorbic acid (AA) has been widely used to improve human health since it was first found, such as resisting scurvy, enhancing immunity, and preventing arteriosclerosis. Moreover, it plays a very important role in the anti-oxidation process in the human body. Therefore, it is of great significance to develop sensitive and accurate detection methods. In this work, silver-coated gold nanorods (Au@Ag NRs) acted as the optical probe, which could be etched with hydroxyl radicals (·OH) from the Fenton reaction between H2O2 and Fe2+, leading to the blue shift of longitudinal localized surface plasmon resonance absorption. However, as a free radical scavenger, AA was able to inhibit the Fenton reaction, resulting in a red shift of plasmon resonance absorption. Based on the change in longitudinal plasma resonance absorption of silver-coated gold nanorods, a linear relationship between the maximum longitudinal absorption wavelength and the concentration of AA was established in the range of 2.5–17.5 μM with a limit of detection (LOD) of 0.48 μM and a limit of quantitation (LOQ) of 1.61 μM, which was feasible to detect AA in tablets.

Flexible Recyclable Cellulose Paper Templated Cu-Doped Polydopamine Membranes with Dual Enzyme-Like Activity.

The development of high-efficiency enzyme mimics is of great significance in the field of biocatalysis. However, it remains challenging to design novel enzyme mimics with multiple enzyme-like activities, excellent stability, and good reusability. Herein, a facile molecular assembly strategy to construct dialdehyde cellulose (DAC) templated Cu-doped polydopamine (DAC@PDA/Cu) membrane with dual enzyme-like activities is presented. The Schiff base bonds formed between polydopamine (PDA) and DAC can not only accelerate the adhesion of PDA thin layer but also contribute to Cu-loading and high stability of DAC@PDA/Cu membrane. Importantly, the assembled DAC@PDA/Cu membrane exhibits a remarkable catalytic activity that is superior to the natural laccase along with high stability and excellent reusability. Moreover, the DAC@PDA/Cu membrane also demonstrates peroxidase-like activity, and it is successfully applied in the sensitive detection of ascorbic acid (AA). This work will provide a new paradigm methodology for rational design and practical applications of enzyme mimics based on bioinspired molecular assemblies.

Luminescent Carbon Nanoclusters for Sensitive Detection of Ascorbic Acid and Fluorescent Printing

Luminescent Carbon Nanoclusters for Sensitive Detection of Ascorbic Acid and Fluorescent Printing

Carbon Cloth-Based Electrochemical Device for Specific and Sensitive Detection of Ascorbic Acid and Tryptophan

Herein, a novel, flexible and inexpensive carbon-cloth based electrochemical device (CCED) is proposed with polyimide (PI) sheet as a base substrate. CC, embedded with numerous microfibers, was used as a sensing substrate. A CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> laser was employed for laser cutting three CC electrodes with desired dimensions, which were bonded on the PI sheet using a double-sided tape. Unmodified CC was used as working and counter electrodes, whereas Ag/AgCl ink modified CC was a reference electrode. For creating a hydrophobic region and insulating the electrodes, lamination process was used. Further ascorbic acid (AA) and tryptophan (Tr) were used as analytes for sensing with natural and unmodified CCED surface. The electrochemical response was analyzed using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Under optimized conditions, the CCED was observed to be capable of determining AA and Tr in a neutral pH (phosphate buffer solution) at 0.4 V and 0.6 V in a linear range of 30 - <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$8000 ~\mu \text{M}$ </tex-math></inline-formula> and 20 – <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$6000 ~\mu \text{M}$ </tex-math></inline-formula> , with LOD of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$21.76 ~\mu \text{M}$ </tex-math></inline-formula> , and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$11.84 ~\mu \text{M}$ </tex-math></inline-formula> respectively at (S/N=3). Additionally, it was thoroughly investigated for common interfering species including Xanthine (Xn), Hypoxanthine (Hx), Uric acid (UA), Cysteine (Cy), Glucose (G) and Folic Acid (FA). The sensing platform was successfully applied for determination of AA and Tr in human real serum sample with appreciable recoveries.

Fabrication of peroxidase-mimic iron oxide/carbon nanocomposite for highly sensitive colorimetric detection

Nanozyme has been one of the most promising artificial enzymes for substitute natural enzymes. The main research focus in this field is developing the nanozymes with high activity, sensitivity and stability. In this paper, prussian blue/polyacrylonitrile (PB/PAN) composite nanofiber was prepared by electrospinning which was calcined to obtain iron oxide/carbon (FeOx/C) composite nanozyme. The structure of the prepared FeOx/C nanozyme was characterized by scanning electron microscopy (SEM), X-ray diffractometer (XRD), Energy dispersive spectrometer (EDS) and X-ray photoelectron spectra (XPS). The results revealed that FeOx/C nanozyme containing the catalytic active species of γ-Fe2O3 possessed peroxidase-like catalytic activity. The catalytic activity of prepared nanozyme which was influenced by different content of PB and different calcination temperatures was investigated. The optimal PB content in the PB/PAN nanofiber and calcination temperature were 41.5% and 600 °C in this research. The prepared FeOx/C nanozyme possessed highly sensitive detection of ascorbic acid. This research provides a new approach to fabricate iron oxide/carbon composite nanozyme with highly catalytic activity and sensitive for colorimetric sensor.

A novel SERS substrate of MIL-100(Fe)/AgNFs for sensitive detection of ascorbic acid in cellular media.

A novel SERS substrate of MIL-100(Fe)/AgNFs was firstly prepared for sensitive and selective detection of ascorbic acid (L-AA), with a LOD of 10−11 M. A spectral decrease of MIL-100(Fe)/AgNFs towards L-AA solution thanks to the efficient capture and reduction of Fe3+ in MIL-100(Fe) constituted the assay, which was demonstrated to function well in food samples and in cellular media for L-AA sensing.

A novel gold nanoparticle-based colorimetric assay for highly sensitive detection of ascorbic acid

In this study, a novel approach for colorimetric detection of ascorbic acid (AA) was proposed based on the peroxidase-like activity of gold nanoparticles, which were synthesized using Oldenlandia corymbosa leaves extract (OC-AuNPs). The OC-AuNPs synthesis was optimized at 0.5 mM Au3+, a reaction time of 20 min, and a temperature of 60 °C. The results showed that the biogenic OC-AuNPs presented as highly-efficient peroxidase mimics for catalyzing H2O2 to oxidize 3,3′,5,5′-tetramethylbenzidine forming a typical blue product with the characteristic absorption at 654 nm. The developed colorimetric method exhibited high sensitivity for AA with a detection limit of 0.26 μM in the linear range of 0 – 100 μM. The proposed assay can be serviced as a sensitive biosensor for the determination of AA in aqueous solutions due to its simple detection procedure, fast operation, and high sensitivity.

An “on-off-on” fluorescent system based on the microwave-assisted preparation of copper-functionalized carbon quantum dots for sensitive detection of ascorbic acid

Carbon dots (CDs) are a unique class of fascinating carbon-based fluorescent sensors with strong photoluminescence, chemical stability and good biocompatibility. In this work, new copper-doped carbon dots (Cu-CDs) were successfully synthesized from citric acid, ammonium tartrate and CuCl2 via a household microwave. The Cu-CDs exhibit excitation-independent emissions, high fluorescence quantum yield (~34.74%) and excellent fluorescence stability. The fluorescence of Cu-CDs can be directly quenched by ascorbic acid (AA) linearly in the range of 0.1–3.0 μM based on the inner filter effect (IFE). The limit of detection (LOD) can be determined to 27 nM. Meanwhile, an “on-off-on” sensing system based on the complex of Cu-CDs and Fe3+ is designed and served as highly specific detection probes for AA through the fluorescence resonance energy transfer (FRET) with a lower LOD of 6 nM, which is one of the best reports. The proposed methods provide obvious advantages of convenience, simplicity, rapid response, high selectivity and sensitivity. Besides, good results also have been acquired for AA detection in real medicine samples.

Poly(methacrylic acid)‐Stabilized Silver Nanoclusters as Colorimetric Sensors for the Rapid and Sensitive Detection of Ascorbic Acid

AbstractA simple, rapid, and sensitive colorimetric assay for ascorbic acid (AA) was developed based on poly(methacrylic acid)‐stabilized silver nanoclusters (PMAA‐AgNCs). The AgNCs were prepared via a single‐step synthesis exploiting PMAA as both a reducing agent and a stabilizer. The sensing capability of this method is based on the color change associated with the growth in size of AgNCs, which turn into nanoparticles, resulting from the reduction of free Ag+ present in AgNCs solution to Ag0 by AA. In the presence of AA, an apparent surface plasmon resonance absorption peak of the silver nanoparticles was observed at 430 nm, and its intensity increased linearly with AA concentration, so that a solution color change could be observed with the naked eye. The proposed method exhibited a linear working concentration range of 0.25–100 μM and a detection limit of 95 nM. The sensor was employed to determine AA concentration in fruit juice and vitamin C tablet samples, affording results of high accuracy.

A novel strategy for sensitive and rapid detection of ascorbic acid via the Tyndall effect of cobalt hydroxide nanoflakes.

Cobalt oxyhydroxide (CoOOH) nanoflakes, as nanoenzymes and fluorescence quenchers, have been widely used in colorimetric and fluorescent analysis. However, their promising light scattering property—the Tyndall effect (TE)—has never been applied in biosensors and biological analysis to date. Herein, we report for the first time a novel strategy for point-of-care detection of ascorbic acid (AA) with the TE of CoOOH nanoflakes providing colorimetric signaling. In this detection system, CoOOH nanoflakes exhibit a strong red TE signal under the illumination of a hand-held 635 nm laser pointer pen. However, the introduction of AA could induce a significant decrease of the TE because it could reduce CoOOH into Co2+ and results in the degradation of the CoOOH nanoflakes. The changes in the TE intensity could be read-out using a smartphone for the portable quantitative analysis of AA. The results showed that this CoOOH nanoflake-based TE-inspired assay (TEA) exhibited a good linear range from 0.25 μM to 40 μM for AA, with a detection limit of 12 nM. It also showed high selectivity toward AA over common potential interfering species. Importantly, this method possessed the advantages of simple operation, low consumption of time and equipment-free analysis and was successfully applied to the detection of AA in vitamin C tablets.