Selective Detection Of Ascorbic Acid Research Articles

Polyvinylpyrrolidone-stabilized Pt nanoclusters as robust oxidase mimics for selective detection of ascorbic acid

In this work, the Pt nanoclusters with an average size of 1.7 ± 0.3 nm were prepared by a facile and green method using polyvinylpyrrolidone (PVP) as both stabilizer and reductant. The oxidase-like activity of PVP-stabilized Pt nanoclusters (PVP-Pt NCs) was investigated by the catalytic oxidation of o-phenylenediamine (OPD). The mechanism studies indicated that PVP-Pt NCs performed as oxidase enzyme mimics by catalyzing the dissolved oxygen to generate the reactive oxygen species (singlet oxygen and superoxide anion) intermediates. Ascorbic acid (AA) could also be oxidized to dehydroascorbic acid (DHA) which could react with OPD to generate a fluorescent compound. On the basis of the robust oxidase-like activity of PVP-Pt NCs, both colorimetric assay and fluorescence method for AA determination were established. Compared with colorimetric assay, the fluorescence method showed higher sensitivity and selectivity for AA detection. The proposed fluorescence method with the LOD of 1.17 μM could overcome the interference of most reducing substances and showed promising applications in biosensor. The as-prepared PVP-Pt NCs possessed intrinsic oxidase-like property by catalyzing dissolved oxygen to ROS (superoxide anions (·O 2 - ) and singlet oxygen ( 1 O 2 )) which could oxide the OPD to OPD ox . The inhibition of AA to the catalytic oxidation of OPD was employed to establish the colorimetric assay for AA determination. AA could also be oxidized to DHA by·O 2 - and 1 O 2 intermediates, and the DHA could react with OPD to form QD with a fluorescence emission peak at 434 nm. The fluorescence method for AA detection was carried out when the solution changed to yellow color which was the signal of the reaction terminal. Comparing with colorimetric assay, the fluorescence method exhibited enhanced sensitivity and selectivity.

Rapid Selective Detection of Ascorbic Acid Using Graphene-Based Microfluidic Platform

In this paper, we present a compact microfluidic platform for selective detection of ascorbic acid. The microfluidic chip was fabricated by xurography technique with microfluidic channel placed between the silver electrodes. To increase the conductivity of the platform and enhance electron transfer process, a graphene sheet was deposited in the gap between the electrodes. The suspension of tablets with ascorbic acid and a mixture of ascorbic acid and isomalt, a sugar substitute, were injected in the microfluidic channel. Measuring electrical parameters at the silver contacts, it was possible to successfully differentiate ascorbic acid from isomalt. The sensing mechanism of the developed microfluidic platform is based on the increase of the overall conductivity with the increase of the concentration of ascorbic acid, resulting in the decrease of the resistive parameters and increase of the capacitive parameters of the proposed equivalent electrical circuit. The addition of graphene was found to improve the response linearity by 5.28% and lower the limit of detection and quantification by 12%, compared to the reference structure without graphene.

Porous silicon-mesoporous carbon nanocomposite based electrochemical sensor for sensitive and selective detection of ascorbic acid in real samples

Ascorbic acid (AA) is one of the vital water-soluble antioxidants in blood serum and can function as a key blood serum biomarker for oxidative stress. Therefore, we have developed a highly sensitive and selective AA electrochemical sensor based on novel porous silicon-mesoporous carbon nanocomposites (PSi-MC NCs) modified glassy carbon electrode (GCE). The structural properties and morphological investigation of the PSi-MC NCs were systematically studied by different techniques. This newly designed PSi-MC/GCE-based non-enzymatic electrochemical sensor can measure an extremely wide range of AA (0.5–2473 μM) in phosphate buffer solution (PBS) with a sensitivity 0.1982 μAμM−1cm−2 and a logical limit of detection (LOD) 30.0±0.1 nM. The proposed AA sensor was also applied to detect possible interference from common interfering substances that are present in human blood, showing highly selective performance. The proposed AA sensor also showed highly acceptable results towards the detection of AA levels in human blood serum and vitamin C tablets. This new combination of active material PSi-MC NCs provided steady, excellent reproducibility, repeatability, and long-term stability.

Nitrogen-doped hierarchical porous carbon nanomaterial from cellulose nanocrystals for voltammetric determination of ascorbic acid

The sensing application of cellulose nanocrystals (CNCs) is fascinating. CNCs can’t produce electrical or optical signals directly. Different from published sensing methods, a novel and simple electrochemical sensor for sensitive and selective detection of ascorbic acid (AA) was constructed based on three-dimensional nitrogen-doped hierarchical porous carbons (NHPC) by carbonizing CNCs and urea. Compared with bare glassy carbon electrode (GCE), the presence of porous carbons effectively increases the electron transport between analytes and the electrode, and significantly reduces the overpotential of AA oxidation. Under the optimum conditions, the electrode comprised of NHPC exhibits an extremely wide linear range from 8 × 10−5 to 1 × 10−2 M (R2 = 0.9996) and 1 × 10−6 to 5 × 10−5 M (R2 = 0.9867) to recognize the AA molecules, with a low detection limit of 2.45 × 10−7 M (S/N = 3) at a sensitivity of 0.1138 μA μM−1 cm−2. In particular, the sensing system for AA detection was further verified by the successful monitoring of AA in some spiked real samples. The fabricated nitrogen-doped CNC-based porous carbon material shows broad potential in the electrochemical application.

Oxidase Mimetic Activity of a Metalloporphyrin-Containing Porous Organic Polymer and Its Applications for Colorimetric Detection of Both Ascorbic Acid and Glutathione

The selective detection of ascorbic acid (AA) and glutathione (GSH) is very significant for dietary guidance and health monitoring. Herein, we prepared a metalloporphyrin-containing porous organic framework (Co-POP) via a facile Friedel–Crafts reaction. Co-POP was able to catalyze the oxidation of colorless 3,3′,5,5′-tetramethylbenzidine (TMB) to a blue substrate (ox-TMB) in the role of dissolved oxygen. The best catalytic performance of Co-POP was realized at 25 °C and pH 4 according to the optimized experiments. Because of the high oxidase-like activity of Co-POP, a simple and sensitive colorimetric assay was established for the determination of AA and GSH in a wide range. The detection limit (LOD) of AA and GSH was calculated to be 1.60 and 0.71 μM, respectively. Finally, the application of the colorimetric sensor for AA and GSH detection in real samples (fruits and diluted serum) was also evaluated, suggesting its great potential for biocatalysis and biosensing.

Selective detection of ascorbic acid with wet-chemically prepared CdO/SnO2/V2O5 micro-sheets by electrochemical approach

Generally, ascorbic acid (AA) is a potent reducing and antioxidant agent that regulates in fighting against bacterial infections as well as detoxifying reactions, which is functioned in the formation of collagen in fibrous tissue, teeth, bones, connective tissue, skin, and capillaries. Up to date, electrochemical enzymatic sensor are significantly used for enzymatic AA detection that exhibits an excellent selectivity, high reliability and handled under physiological conditions. However, considering some intrinsic dis-advantages of using enzymes, such as high fabrication cost and poor stability, non-enzymatic AA sensors have attracted increasing research interest in recent years owing to their low cost, high stability, fast response, and low detection limit. Moreover, the development of nanotechnology has also offered new opportunities to develop the nanostructured sensor probes for enzyme-less AA sensing applications. With beneficial advantages, ternary-doped metal oxides have gathered an extensive effort in the development of cost-effective sensors with high stability, sensitivity and quick response for the determination of selective AA by enzyme-free detection. In this approach, the mixed metal oxides of CdO/SnO2/V2O5 micro-sheets (MSs) were prepared by facile wet-chemical method in alkaline phase at low temperature. Later, it was subjected to detail characterize by using various methods such as XPS, FESEM, EDS, and XRD. The slurry of prepared MSs in ethanol was deposited initially onto the surface of glassy carbon electrode (GCE) to make a thin film with conducting nafion (5% suspension in ethanol) adhesive to result the working electrode of proposed AA sensor probe. The sensor sensitivity (21.3354 μA μM−1 cm−2) is calculated by using the slope (0.6742 μA μM−1) of the calibration curve by considering the active surface area of GCE (0.0316 cm2) in the linear dynamic range (LDR; 0.1 nM to 0.01 mM). The limit of detection (LOD) (98.64 ± 4.98 pM) is obtained from the calibration curve. The proposed AA electrochemical sensor exhibits short response time, good reproducibility and successive outcome during the investigation of the real biological samples. The development of enzyme-free AA sensor by using CdO/SnO2/V2O5 MSs onto GCE is simple as well as reliable and practically able to detect the biological stuffs for the safety of human health in the field of biomedical and sensor technology.

A ratiometric electrochemiluminescence sensing platform for robust ascorbic acid analysis based on a molecularly imprinted polymer modified bipolar electrode

Herein, a novel molecularly imprinted polymer (MIP) modified spatial-resolved “on-off” ratiometric electrochemiluminescence (ECL) sensing platform based on a closed bipolar electrode (BPE) has been reported for highly accurate and selective detection of ascorbic acid (AA). AA-imprinted MIP was decorated on the anode of the BPE, and Ru (bpy)32+ in the anode electrolyte served as anode-emitter, while ZnIn2S4 as the other ECL emitter was coated on the cathode. Rebinding of AA at anode promoted ECL response of ZnIn2S4 (440 nm) at cathode. Meanwhile, the ECL response at 605 nm decreased, arising from the hindered reaction of Ru (bpy)32+ on the anode surface. Therefore, an “on-off” BPE-ECL sensing platform was fabricated and showed distinguished performance in repeatability and selectivity thanks to the ratio correction effect and the specific recognition from MIP. The linear range for AA detection is from 50 nM to 3 μM with a low detection limit of 20 nM (S/N = 3). The assay deviation of the ratio responses largely declined by about 15 and 5 times compared with the ones from single pole in the aspect of repeatability and long-term stability, respectively. This work provides a reliable and stable sensing pattern for practical application, which also furnishes a strategy for designing simple and low-cost ECL sensing devices.

Fluorescent silver nanoclusters stabilized in guanine-enhanced DNA hybridization for recognizing different small biological molecules

Fluorescent DNA-stabilized Ag nanoclusters (DNA/Ag NCs) plays significant roles in biochemical detections due to their high fluorescence quantum yield, high stability and good biocompatibility. In this paper, two guanine-enhanced fluorescence DNA-stabilized silver nanoclusters were designed to study the effect of guanine coating degree on silver nanoclusters fluorescence and their interactions with small biological molecules. The results indicated that the degree of guanine coating had a slight influence on the fluorescence of the two DNA/Ag NCs, however, the two DNA/Ag NCs had different fluorescence response when interacting with different small biological molecules. The fluorescence of the DNA/Ag NCs wrapped in the guanine-rich strand could be quenched by small biomolecules such as ascorbic acid, dopamine and cysteine, while the fluorescence of the DNA/Ag NCs approached to the guanine-rich strand could only be quenched by dopamine and cysteine. Based on this interesting phenomenon, an analytical method for recognition of ascorbic acid, dopamine and cysteine from other small biological molecules can be established by measuring the fluorescence change of DNA/Ag NCs and a method for selective detection of ascorbic acid in the absence of dopamine and cysteines can be achieved by combining the two DNA/Ag NCs probe.

A nanocomposite of NiFe2O4-PANI as a duo active electrocatalyst toward the sensitive colorimetric and electrochemical sensing of ascorbic acid.

A non-enzymatic ascorbic acid sensor using a nickel ferrite/PANI (NF–PANI) nanocomposite and based on colorimetric and electrochemical sensing methods was investigated in this study. The nanocomposite was prepared by an in situ polymerization and utilized as an electrocatalyst to sense ascorbic acid (AA) through the peroxidase mimic sensing of H2O2 in the presence of 3,5,3,5-tetramethylbenzidine (TMB) as a coloring agent. It was also utilized to detect AA present in real samples prepared from fruit extracts, commercial beverages, and vitamin-C tablets. The limit of detection (LoD) for AA sensing by the peroxidase mimic method was found to be 232 nM. The relative standard deviation (RSD) calculated for analysis of the real samples analysis ranged from 1.7–3.2%. Similarly, the electrochemical sensing of AA by NF–PANI was examined by cyclic voltammetric, chronoamperometric, and differential pulse voltammetric analyses. The LoD for the electrochemical method applied to AA sensing was 423 nM. The nanocomposite functioned as an effective electrocatalytic sensing agent in both methods to selectively detect AA due to the combined effect of NF and PANI. Thus, it was shown that the nanocomposites could be utilized for the laboratory-based detection of AA by various methods and could give rapid results.

Detection of Ascorbic Acid Using Green Synthesized Carbon Quantum Dots

In this work, carbon quantum dots (CQDs) were synthesized by microwave irradiation and were electropolymerized on glassy carbon electrode (GCE) to establish an electrochemical sensor for the selective detection of ascorbic acid (AA). Electrochemical behaviors of the prepared sensor were investigated by cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS). Herein, two wide linear responses were obtained in ranges of 0.01-3 mM and 4-12 mM with a low detection limit of 10 μM to AA. High sensitivities (44.13 μA-1 μM-1 cm-2, 9.66 μA-1 μM-1 cm-2, respectively) corresponding to the linear ranges were also achieved. In addition, the electrochemical sensor exhibited good selectivity and robust anti-interference ability toward AA in the presence of dopamine (DA) and uric acid (UA). These results showed that this sensor can be used as a promising tool to detect AA in real complex systems.

Carbon-Shielded Three-Dimensional Co–Mn Nanowire Array Anchored on Ni Foam with Dual-Enzyme Mimic Performance for Selective Detection of Ascorbic Acid

Carbon-shielded 3D Co–Mn nanowire array on Ni foam (CoMn NW/NF@C) was successfully prepared by the solvothermal and thermal annealing processes. The CoMn NW/NF@C exhibits peroxidase/catalase dual-m...

Tuning the luminescence of nitrogen-doped graphene quantum dots synthesized by pulsed laser ablation in liquid and their use as a selective photoluminescence on–off–on probe for ascorbic acid detection

In this work, nitrogen-doped graphene quantum dots (N-GQDs) were synthesized by pulsed laser ablation in liquid using Nd:YAG laser (532 nm). Graphite target was ablated in dimethylformamide, as solvent and nitrogen source, and the microstructure as well as optical properties of N-GQDs were studied. The N-GQDs structure consists of a graphitic core with oxygen and nitrogen functionalities and particle size about 3 nm, as demonstrated by X-ray photoelectron spectroscopy, Raman spectroscopy and transmission electron microscopy. The as-prepared N-GQDs structure was modified by solvothermal treatment at 65, 90 and 120 °C reducing the oxygen functional groups, adding nitrogen and restoring the π-conjugated structure of N-GQD. The N-GQDs exhibit UV–Vis absorption spectrum with the characteristic π-π* and n – π* electronic transitions of the GQDs with a large amount of oxygen and nitrogen functionalities. These N-GQDs exhibited a visible light photoluminescence centered at 486 nm upon an excitation of 410 nm and the photoluminescence intensity enhanced up to 4.05% of quantum yield after solvothermal treatment. The N-GQDs dispersion was used for selective detection of ascorbic acid, through a signal-off and signal-on system. The results show the use of N-GQDs as a competent photoluminescence sensor for metal ions and ascorbic acid.

Electrochemical sensor based on Ni/reduced graphene oxide nanohybrids for selective detection of ascorbic acid

Nowadays, graphene is integrated with different nanomaterials to form unique composite materials. Decorating the surface of graphene sheets with Ni nanoparticles (Ni NPs) is one of the popular methods. In this paper, a newly advanced electrochemical sensor based on the nanohybrid of graphene oxide modified with Ni NPs was developed with a facile and effective one-pot solvothermal strategy, which was synthesized by using hydrothermal method and followed calcining under Ar flow. The as-prepared composites were characterized via X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), infrared spectrometry, and voltammetric methods. The results reveal that Ni/reduced graphene oxide (rGO) composite exhibit remarkable electrocatalytic performance toward detecting ascorbic acid (AA). After calcination in the argon gas at 450 °C, as-synthesized Ni/rGO has uniform particle size distribution with the average particle size of 10 nm. The corresponding line arrange and detection limit are estimated to be from 0.01 mM to 1.15 mM (r = 0.99919) and 0.61μM at a signal-to-noise ratio of 3.

Sandwich-structured nanoparticles-grafted functionalized graphene based 3D nanocomposites for high-performance biosensors to detect ascorbic acid biomolecule

We present a highly sensitive and selective nano-biosensor for rapid, stable and highly reproducible detection of ascorbic acid (AA) in the presence of dopamine, uric acid and other interferences by a three-layer sandwich arrangement of nitrogen-doped functionalized graphene (NFG), silver nanoparticles (AgNPs) and nanostructured polyaniline (PANI) nanocomposite. The enhanced AA electrochemical properties of the NFG/AgNPs/PANI electrode is attributed to the superior conductivity of the NFG-PANI and the excellent catalytic activity of AgNPs. The critical modification of the AgNPs-grafted NFG-PANI coated on very low-cost fluorine doped tin oxide electrode (FTOE) increased the charge transfer conductivity of the electrode (the resistance drops down from 11,000 Ω to 6 Ω). The nano-biosensor was used to accurately detect AA in vitamin C tablets with the recovery of 98%. The sensor demonstrated a low detection limit of 8 µM (S/N = 3) with a very wide linear detection range of 10–11,460 µM, good reproducibility and excellent selectivity performance for AA detection. The results demonstrate that this nanocomposite is a promising candidate for rapid and selective detection of AA in practical clinical samples.

Hydrothermal Synthesis of Boron Nitride Quantum Dots/Poly(Luminol) Nanocomposite for Selective Detection of Ascorbic Acid

Boron nitride quantum dots (BNQDs) were synthesized hydrothermally using boric acid and urea. High-resolution transmission electron microscopy (HR-TEM) analysis confirmed the formation of BN quantum dots with the lattice size of 0.227 nm. Fourier-transform infrared (FT-IR) and Ultraviolet–visible (UV-Vis) spectroscopies revealed the B-N, O-H and N-H bond formation in the BNQDs and the maximum absorption wavelength at 269 nm. BNQDs exhibited strong fluorescence emission at a wavelength of 330 nm. Furthermore, BNQDs were coated onto a glassy carbon electrode (GCE). Followed by, poly(luminol) (Plu) was electrochemically deposited onto BNQDs/GCE from 0.1 M H2SO4 containing 0.5 mM luminol in order to prepare nanocomposite (hybrid film) coated electrode with improved stability and electrochemical activity. Due to unique nature and synergetic effect between BNQDs and Poly(luminol), as-prepared hybrid Plu/BNQDs film coated GCE showed improved electrocatalytic activity for vitamin C (ascorbic acid, AA) oxidation at 0.2 V. The calibration graph was obtained from 10 to 100 μM AA by amperometry and limit of detection (LOD) was found to be 1.107 μM. The interference effects were also carried out in the presence of uric acid (UA), dopamine (DA) and glucose (Glu). Interestingly, UA, DA and Glu did not produce significant responses on the Plu/BNQDs/GCE which indicated good selectivity of the sensor for AA. Moreover, Plu/BNQDs/GCE based sensor showed reproducible and repeatable analytical performances. We propose that the Plu/BNQDs based hybrid film can be used as a selective sensor probe for the detection of the AA.

Non-oxidation reduction strategy for highly selective detection of ascorbic acid with dual-ratio fluorescence and colorimetric signals

Ascorbic acid (AA), one of the most important vitamins, acts a critical role in various physiological reactions and is involved in many diseases. Thus, the development of highly selectivity methods for detecting AA level with the presence of different reducing substances is of great significance in complicated serum matrix. In this paper, a non-oxidation reduction regulation (NRR) strategy was designed to construct a novel dual-ratio fluorescence and colorimetric dual-readout assay for highly selective detection of AA. The strategy involves three processes: Ag+ oxidated o-phenylenediamine (OPD) to 2,3-diaminophenazine (OPDox), AA inhibited the generation of OPDox and the AA was oxidized to dehydroascorbic acid (DHAA). The specific performance of DHAA NRR, due to the condensation reaction between dicarbonyl group of DHAA and diamine group of OPD, that is confirmed by ESI-MS and 1H NMR spectra analysis, can remarkably enhance the selectivity of AA detection. Additionally, the proposed method based on NRR strategy not only provides a sensing platform for probing AA but also shows promising outlook in biomedical studies.

Silver nanoparticles decorated stain-etched mesoporous silicon for sensitive, selective detection of ascorbic acid

Novel silver nanoparticles decorated porous silicon (AgNPs-PSi) was fabricated via stain etching of Si, followed by simple immersion plating of Ag and applied successfully for enhanced electro-oxidation and quantification of ascorbic acid (AA). The newly developed nanocomposite consists of mesoporous Si (<20 nm) decorated by crystalline 15–50 nm AgNPs. Remarkable sensing performance was achieved with high sensitivity (1.279 μA μM cm−2), fast response time (<5 s), wide linear range (20–600 μM: R2 = 0.9933), low limit of detection (0.83 μM at S/N = 3) and excellent anti-interference and repeatability behavior. The current Ag-PSi modified glassy carbon electrode was further applied to a commercially available vitamin C supplement with satisfactory detection result.

Simultaneous Determination of Ascorbic Acid, Uric Acid and Tryptophan by Novel Carbon Nanotube Paste Electrode.

In the present paper, electrochemical methods were used to investigate the behavior of ascorbic acid at a carbon paste electrode modified with 2,2'-((1E)-(1,2 phenylenebis(azanylylidene)) bis(methanylylidene))bis(benzene-1,4-diol) (PBD) and oxidized multiwall carbon nanotubes. The modified carbon paste electrode showed high electrocatalytic activity toward ascorbic acid; the current was enhanced significantly relative to the situation prevailing when an unmodified carbon paste electrode was used. Cyclic voltammetry was used to investigate the redox properties of this modified electrode at various solution pH values and at various scan rates. Using differential pulse voltammetry, the calibration curves for AA were obtained over the range of 1.0-80.0 and 80-4000.0 μM, respectively. The detection limit was 0.3 μM. The present method provides a simple method for selective detection of ascorbic acid. DPV also was used for simultaneous determination of AA, uric acid, and tryptophan at the modified electrode. Finally, the proposed electrochemical sensor was used for determinations of these substances in in biological systems and pharmaceutical samples.

Fluorescent and photoacoustic bifunctional probe for the detection of ascorbic acid in biological fluids, living cells and in vivo.

Photoacoustic imaging (PAI) has emerged as a promising clinical technology, thanks to its high-resolution in deep tissues. However, the lack of specificity towards analytes limits further application of the PA probe in molecular imaging. To this end, we herein report a PA and fluorescence (FL) dual-modal probe for the selective detection of ascorbic acid (AA). To realize this design, cobalt oxyhydroxide (CoOOH) was adopted as a multifunctional platform (PA contrast agent, FL quencher and specific oxidant to AA) and hybridized with red-emissive carbon dots (RCDs). In the presence of AA, CoOOH is reduced to Co2+ and meanwhile releases RCDs, resulting in the decrease of PA and recovery of FL signals. We demonstrated the AA detection capabilities of the probe in complicated biological fluids (human serum and urine), living cells, and dual-modal FL/PA imaging in vivo. This work revealed the PAI capacity of CoOOH for the first time, which may inspire researchers to design other CoOOH-based PA probes and further employ RCDs in biology and the clinic.

Rapid and sensitive colorimetric detection of ascorbic acid in food based on the intrinsic oxidase-like activity of MnO2 nanosheets.

In this paper, we report a colorimetric sensor for the rapid, selective detection of ascorbic acid (AA) in aqueous solutions. Single-layered MnO2 nanosheets were established as an artificial oxidase; consequently colorless 3,3´,5,5´-tetramethylbenzidine (TMB) was oxidized to a blue product (oxTMB), with increase in absorbance at 650 nm. The absorbance of the reaction system decreased after introduction AA, which reduced MnO2 into Mn2+ . Under optimum conditions, a detection limit of 62.81 nM for AA in aqueous solutions could be achieved. The linear response range for AA was 0.25-30 μM with a correlation coefficient of 0.996. Importantly, the MnO2 nanosheet-TMB chromogenic reaction exhibited great selectivity as there was no interference from other metal ions, amino acids and small biological molecules. The proposed colorimetric sensing of AA could be applied for fruit, juice and pharmaceutical samples. Moreover, the proposed sensor showed satisfying performance, including low cost, easy preparation, rapid detection, and good biocompatibility.