Selective Detection Of Ascorbic Acid Research Articles

Ultrathin PtTeNi nanosheets as a peroxidase mimic for colorimetric detection of ascorbic acid

Utilizing the peroxidase (POD) activity of nanozymes to construct the colorimetric sensors is a popular strategy for assessing the antioxidant capacity of biological molecules, but the detection sensitivity is often compromised by their low enzymatic activity. Pt-based nanozymes, favored by their regulated nanostructures, well provide numerous binding sites for H2O2, and exhibit enhanced POD performance. Here, we utilized a simple hydrothermal method to synthesize PtTeNi nanomaterials featured with the ultrathin sheets for detecting biological antioxidant (ascorbic acid (AA) as the model). With the TMB-H2O2 system as the colorimetric substrate, PtTeNi nanomaterial exhibited superior POD-like activity with a higher Vmax (5.02 × 10−4 mM s−1) and lower Km (3.14 mM)) in contrast to natural HRP. AA significantly inhibited the colorimetric reaction of PtTeNi-TMB-H2O2 system via competitively binding OH generated by PtTeNi-mediated H2O2 catalysis and further blocking oxTMB formation. Inspired by this fact, the PtTeNi-TMB-H2O2 colorimetric sensor successfully realized highly sensitive and selective detection of AA with a good linear range from 5 μM to 500 μM and the detection limit of 2.94 μM. For analyzing the total antioxidant capability and AA contents in actual samples (commercial drinks and vitamin C tablets), the PtTeNi-based colormetric method displayed comparable results with the commercial total antioxidant capacity assay kit, with the advantages of easy operation, convenient storage and high stability. This work fully affirms the excellent enzyme-like performance of Pt-based nanomaterial and confirms the feasibility of nanozymes-based colorimetric sensing strategy in detecting antioxidant capability of biological molecules.

Highly sensitive colorimetric detection of ascorbic acid using molecularly imprinted photonic crystal hydrogel sensor

Molecular imprinted photonic crystal hydrogel (MICPH) sensors have gained recognition as an efficient platform for selectively detecting analyte molecules. In the present work, we report the development and implementation of a colorimetric sensor based on MIPCH for the selective detection of Ascorbic acid (AA). The fabrication process of the MIPCH sensor involves the photo-polymerization of a hydrogel precursor solution containing AA molecules, which is encapsulated in the interstitial spaces of photonic crystal (PC) opal film. Following the encapsulation, these molecules are selectively removed from the hydrogel network, forming an AA-MIPCH sensor. The sensor exhibits a vivid structural color that redshifts upon rebinding with different concentrations of AA molecules. This alteration in structural coloration serves as a straightforward and visually discernible indicator of the sensor response and enables the quantitative measurement of the target molecule. The sensor exhibits remarkable sensitivity, featuring a low limit of detection (LoD) of 0.011 µM with high selectivity, minimal response time, and promising long-term stability. In addition, the sensor demonstrates its capability to detect the AA even from the complex matrix. A CNN-based deep learning algorithm in MATLAB® was employed to quantitatively predict the concentration of the target molecule. The integration with the machine learning algorithm yields a highly efficient and accurate smart sensor system that is well-suited for real-time sensing of ascorbic acid.

A ratiometric fluorescence sensor based on Mn doped ZnS QDs for highly selective detection of ascorbic acid

A ratiometric fluorescence sensor based on Mn doped ZnS QDs was designed to detect ascorbic acid with highly selectivity. The synthesized Mn doped ZnS QDs showed a new luminescence performance due to new electron hole recombination center formed in the nanocrystals. The dopant-related luminescence of Mn2+ appeared at 590 nm, and the best dopant-related luminescence effect can be obtained by changing the doping amount of Mn2+ during the synthesis process. Ascorbic acid (AA) is known to be oxidized by Fe3+ to generate dehydroascorbic acid (DHAA). If DHAA combined with o-phenylenediamine (OPD), a fluorescent product quinoxaline DFQ was obtained. Mixing DFQ with Mn doped ZnS QDs, two fluorescence emission appeared at 434 nm and 590 nm. After optimizing the concentration of Fe3+ and OPD, solution pH and reaction time, the results showed a good linear relationship between AA and the ratio of F434/F590. The linear range of this ratiometric fluorescence sensor for detection of ascorbic acid were 0.5–40 μmol·L−1 and 40–80 μmol·L−1, and the detection limit was low to 0.21 μmol·L−1. Compared with the single fluorescence analysis method for AA detection, this work has stronger anti-interference and greatly improved sensitivity and selectivity by ratiometric fluorescence.

Detection of ascorbic acid by persistent luminescent nanoparticles based on CoOOH nanosheets modification.

Persistent luminescent nanomaterials (PLNPs) Zn0.8Ga2O4: Cr3+, Zr3+ with high brightness and good dispersion were prepared by hydrothermal method. The PLNPs were used as luminescent units, and CoOOH nanosheets were used as quenching agents. Based on the fluorescence internal filtering effect, the luminescence of PLNPs were effectively quenched by CoOOH modification on the surface of PLNPs. However, the introduction of ascorbic acid (AA) restored the luminescence of PLNPs and successfully achieved highly sensitive and selective detection of AA. This was due to a selective redox reaction between CoOOH and AA, in which CoOOH was reduced to Co2+. The degree of luminescence recovery of PLNPs showed a good linear relationship with AA concentration in the range 5-250 µM, with a detection limit of 0.72 µM. Therecovery of actualspikedsamples were 97.9-102.2%. This method isexpected to provide reference for the study of other redox substances in biological systems.

Selective detection of ascorbic acid by tuning the composition and fluorescence of the cesium lead halide perovskite nanocrystals

Lead halide perovskite nanocrystals (PNCs) have attracted intense attention due to their excellent optoelectronic properties. In this work, a series of water-stable CsPb(Br/I)3 PNCs fluorescent probes were prepared using an anion exchange method. It was found that the PNCs probes could be used to detect ascorbic acid (AA) in water, and interestingly, the FL spectra of the PNCs probes can be adjusted by controlling the concentration of KI in anion exchange to improve the detection selectivity of AA. The high sensitivity and selectivity make CsPb(Br/I)3 PNCs an ideal material for AA sensing. The concentration of AA can be linearly measured in the range from 0.01 to 50 μM, with a detection limit of 4.2 nM. The reason for the enhanced FL of CsPb(Br/I)3 PNCs was studied, and it is considered that AA causes the aggregation of CsPb(Br/I)3 PNCs. This strategy of improving the selectivity of the probe to the substrate by adjusting the spectrum will significantly expand the application of PNCs in the field of analysis 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.

Dual-spot ratiometric microfluidic paper-based analytical device for accuracy and precision improvement

Instrumental and environmental fluctuations are common sources of error in smartphone-based optical detection, significantly affecting the accuracy of analytical measurements. In this regard, spotting the sample and reference simultaneously and in close proximity compensates for the fluctuations. This “dual-spot” design is similar to the double-beam technique used in spectrophotometry, which reduces fluctuations in the results. The underlying hypothesis is that any instrumental and/or environmental factors influencing the color intensity in the detection zones will similarly impact the color intensity in the control zone under the same conditions. To test our design, a ratiometric microfluidic paper-based analytical device (μPAD), functionalized with a mixture of green-emissive carbon dots (CDs) and red-emissive ethidium bromide, was developed for the selective detection of ascorbic acid (AA). The green emission of the CDs is quenched by both AA and Fe3+; NaF was thus loaded onto the 3D connector as a masking agent to remove the interference effect of the Fe3+ ions. The color variations were monitored under a UV lamp, using a smartphone to capture the images, and the RGB intensities were processed using the Color Grab application. The proposed double-spot method greatly enhanced the analytical precision and accuracy of the device. A linear working range from 0 to 125 μM was obtained, and the limit of detection was 2.71 μM. The μPAD was successfully used for the detection of AA in human serum, with recoveries from 87.27 to 98.52 %.

Development of turn-on fluorescent sensor based on green emissive carnosine-modified tannic acid carbon dots for the selective detection of ascorbic acid

Ascorbic acid (AA) is an indispensable biological antioxidant with anti-aging potential in neurological disorders such as Parkinson’s and Alzheimer’s. Its abnormal concentrations in physiological fluids like human serum can lead to neurological complications. In this study, a turn-on fluorescent sensor was developed using dipeptide (i.e., carnosine) modification of the polyphenolic tannic acid (TA) carbon dots (CDs) (TATA-CDs) for AA detection. Blue-fluorescent TATA-CDs were synthesized using the hydrothermal treatment of the TA and ethylene glycol-bis(β-aminoethyl ether)-N,N,N′,N′-tetraacetic acid (EGTA) as a nitrogen (N) dopant. TATA-CDs were functionalized with carnosine (TATA-Car CDs) using a facile stirring reaction. Their morphological and optical properties were studied via TEM, XRD, UV–Vis, and fluorescence spectroscopy. TATA-Car CDs displayed green fluorescence with excitation and emission wavelength maxima of 400 and 509 nm, respectively. These novel CDs are responsible for the selective turn-on fluorescence sensing of AA (0 to 15 nM) when mixed with copper (Cu2+) ions and deliver a low detection limit of 1.34 nM. The practicality and feasibility of TATA-Car CDs were investigated in human serum samples. From this perspective, the proposed fluorescent sensor is more suitable for the real-time monitoring of AA in different neurological disorders.

The g-C3N4/BSA@MnO2 nanocomposites fluorescent off-on probe for detection and imaging of ascorbic acid in living cells

g-C3N4/BSA@MnO2 fluorescent off-on probe was constructed for sensitive and selective detection of ascorbic acid (AA). BSA@MnO2 nanoparticles using bovine serum albumin (BSA) as a template were anchored on the surface of graphite-phase carbon nitride nanosheets (g-C3N4 NSs) via electrostatic attraction to synthesize the g-C3N4/BSA@MnO2 nanocomposites. The fluorescence of g-C3N4 NSs was quenched by BSA@MnO2 nanoparticles (NPs) via fluorescence resonance energy transfer (FRET) and recovered in the presence of AA via the redox reaction between AA and MnO2. The nanocomposites therefore realized the fluorescent off–on detection of AA. Asatisfactory linear range of 0–120 μM and a limit of detection of 133 nM were obtained. The nanoprobe was applied for the detection of AA in food and drug samples as well as the fluorescent images of exogenous AA in Raw cells. The results showed that the nanoprobe possessed excellent properties for AA detection and broadened the biochemical analysis applications of g-C3N4-based nanomaterials.

Ce4+/Ce3+ as the switch of AIE-copper nanoclusters for highly selective detection of ascorbic acid in soft drinks

An ultrasimple “turn-on” sensor for indirectly detecting ascorbic acid (AA) was prepared using N-acetyl-L-cysteine stabilized copper nanoclusters (NAC-CuNCs) via the AIE (aggregation-induced emission) effect controlled by Ce4+/Ce3+ redox reaction. This sensor fully utilizes the different properties of Ce4+ and Ce3+. Non-emissive NAC-CuNCs were synthesized by a facile reduction method. NAC-CuNCs easily aggregate in the presence of Ce3+ due to AIE, resulting in fluorescence enhancement. However, this phenomenon cannot be observed in the presence of Ce4+. Ce4+ possesses strong oxidizing ability and produces Ce3+ by reacting with AA via a redox reaction, followed by switching on the luminescence of NAC-CuNCs. Moreover, the fluorescence intensity (FI) of NAC-CuNCs increases with the concentration of AA in the range of 4–60 µM, with the limit of detection (LOD) as low as 0.26 µM. This probe with excellent sensitivity and selectivity was successfully used in the determination of AA in soft drinks.

A non-oxidation reduction strategy for highly selective detection of ascorbic acid by “on-off-on” photoluminescence switches

Great progress was made to detect ascorbic acid (AA) based on the photoluminescent nanoprobes/oxidant complexes by using the reducibility of AA. However, some reducing substances including cysteine and glutathione disturbed the accuracy of AA assay. Herein, a non-oxidation reduction regulation strategy was fabricated to construct a novel “on-off-on” photoluminescence model for highly selective determination of AA. Initially, copper nanoclusters capsulated into zeolitic imidazolate framework-8 (CuNCs@ZIF-8) was achieved. And then inorganic phosphate ions quenched the emission of CuNCs@ZIF-8 owing to the decomposition of ZIF-8 shell, rendering the signal in “turn-off” state. The linear range for phosphate ions was 1.0–60 μM with LOD of 0.35 μM. Interestingly, upon introducing AA into CuNCs@ZIF-8/phosphate, the emission of CuNCs@ZIF-8 recovered possibly due to the electronegativity improvement of metal core and surface rigidified through hydrogen bond interaction, and the system signal was “turned-on”. The LOD of AA was as low as 51 nM in a good linear range from 0.1 to 40 μM. Furthermore, CuNCs@ZIF-8 were used for AA detecting in tablets, beverages, and fresh fruits with the satisfactory recoveries from 96% to 104%. More importantly, a paper-based analytical device containing CuNCs@ZIF-8/phosphate were evaluated for the visual sensing of AA in food safety.

An irreversible paper-based profluorescent nitroxide probe for the selective detection of ascorbic acid.

Ascorbic acid (AA) or vitamin C plays multiple crucial roles, particularly as an antioxidant. This essentially biologically active molecule was selectively detected over other reductants by the synthesized profluorescent nitroxide probe ProN6via a switch-on method. After either a hydrogen atom or single electron transfer from AA to nitroxide, the resulting diamagnetic hydroxylamine was rapidly cyclized to form a fluorescent O-acylalkoxyamine. This cyclization prevented the reoxidation of the corresponding hydroxylamine to the nitroxide, leading to a high precision of detection. A kinetic fluorescence study indicated that ProN6 exhibited higher reactivity than ProN7. Density functional theory (DFT) calculations indicated that the Gibbs free energy of the AA-induced cascade reductive lactonization of ProN6 was lower than that of ProN5 and ProN7. The designed probe achieved the sensitive and specific detection of AA with detection limits of 77.9 nM and 195.9 μM in solution and on paper, respectively. The utilization of the probe as a paper-based fluorescent sensor demonstrated the good accuracy of the quantitative analysis of AA in commercial supplements.

A novel electrochemical aptasensor based on polyaniline and gold nanoparticles for ultrasensitive and selective detection of ascorbic acid.

Ascorbic acid (AA) is involved in many physiological activities of the body and plays an important role in maintaining and promoting human health. It is also present in many natural and artificial foods. Therefore, the development of highly sensitive and accurate AA sensors is highly desirable for human health monitoring, as well as other commercial application fields. Herein, an ultrasensitive and selective electrochemical sensor based on an aptamer was developed for the determination of AA for the first time. The aptasensor was fabricated by modifying a composite made of polyaniline (PANI) and gold nanoparticles (AuNPs) on a glassy carbon electrode. The morphologies and electrochemical properties of the resulting electrodes were characterized by various analytical methods. The results indicated relatively good electrical conduction properties of PANI for accelerated electron transfer. The modification with AuNPs provided signal amplification, suitable for applications as novel platforms for the sensitive sensing of AA. Under optimized conditions, the proposed aptasensor displayed a wide linear response toward the detection of AA from 1.0 to 1.0 × 105 ng L-1 coupled with a low detection limit of 0.10 ng L-1. The sensor also exhibited excellent selectivity and high stability, with at least 2000-fold higher sensitivity than similar previously reported methods. Importantly, the aptasensor exhibited promising properties for the determination of AA in real fruits, vegetables, and infant milk powder, thereby showing potential for food analysis.

Preparation of biomass-waste-derived carbon dots from apricot shell for highly sensitive and selective detection of ascorbic acid

• Low-cost synthesis of CDs was firstly achieved with biomass-waste apricot shell • The CDs showed good fluorescent response towards AA in the Fe 3+ -CDs system • A fluorescent sensor for AA was successfully fabricated based on CDs • The AA sensor is applicable for sensitive detection of H 2 O 2 in real samples An ascorbic acid (AA) fluorescence sensor was built using biomass-waste-derived carbon dots (CDs). The CDs were prepared using apricot shell biomass, which serves as an abundant starting source. The prepared CDs displayed good dispersion, uniform particle size, high photostability, and a greenish-yellow luminescence. The experimental results confirmed the greenish-yellow fluorescence was selectively quenched by Fe 3+ and then recovered selectively upon adding AA to the Fe 3+ -CD system, exhibiting an off-on phenomenon. The recovered fluorescence intensity was linear with AA concentration. The linear range is 1-100 μM and detection limit is 40 nM. Analysis of a real sample was also carried out to determine the AA content in human urine. The proposed strategy allowed efficient use of discarded apricot shells that have good economic, environmental, and medical benefits.

Ionic liquid-functionalized carbon dots with positive surface charge for selective detection of ascorbic acid

Ionic liquid-functionalized carbon dots with positive surface charge for selective detection of ascorbic acid

Amino-functionalized perylenediimide derivative with dual fluorescence emission for the detection of ascorbic acid in vivo and in vitro.

The rapid, sensitive, and selective detection of ascorbic acid (AA) is of significance in medical assays and diagnostics. In this work, a new aminoperylenediimide (APDI) derived ratiometric fluorescent probe based on the specific redox reaction of cobalt oxyhydroxide (CoOOH) and AA was constructed. APDI exhibited dual fluorescence emission peaks at 549 and 596 nm with an excitation wavelength of 494 nm. In the presence of CoOOH, the dual fluorescence could be quenched. The dominant fluorescence quenching mechanism was caused by the inner filter effect. Using the red emission as a reference, the fluorescence intensity ratio (F549 /F596 ) was linearly correlated with the concentration of AA over a range of 0.05 to 1μM. The limit of detection for AA was found to be 17 nM. Importantly, the probe was successfully used to detect AA in living cells. Therefore, this high sensitivity and selectivity strategy could directly survey the AA levels in real samples.

A Continuously Tunable Full-Color Emission Nitrogen-Doped Carbon Dots and for Ultrasensitive and Highly Selective Detection of Ascorbic Acid.

Nitrogen-doped carbon dots exhibiting excitation-dependent full-color emissions (F-NCDs) were prepared via the one-step hydrothermal method with citric acid and phenylenediamine. Specifically, the emission wavelength of the F-NCDs tuned from 452 nm to 602 nm due to the introduction of new energy levels by C=O and C=N functional groups. We exploited its stability in illumination, ionic strength, and pH, as well as its specificity, sensitivity, especially in ascorbic acid (AA) detection. F-NCDs could measure the AA concentration in the linear ranges of 0~0.1 and 0.1~1 mmol/L with the detection limit (LOD, S/N = 3) as low as 2.6 nmol/L. Additionally, we successfully detected AA in bovine serum with our F-NCDs and obtained the result within 1 min. Because of full-color emission features, we believe our F-NCDs have a great potential in fluorescent sensor detection.

Solid‐state Synthesis of Cu doped CDs with Peroxidase‐mimicking Activity at Neutral pH and Sensing of Antioxidants

AbstractCarbon dots with peroxidase‐mimicking properties have attracted considerable attention for various sensing and biomedical applications. However, most peroxidase nanozymes do not show activity at neutral pH and only work in acidic conditions. In this work, crystalline Cu‐doped, Mn‐doped, and undoped carbon dots (CDs) are prepared via one‐step, solid‐state, microwave synthesis. Among them, Cu‐CDs demonstrate catalytic oxidation of 3,3′,5,5′‐tetramethylbenzidine (TMB) and 2,2′‐azino‐bis (3‐ethylbenzthiazoline‐6‐sulfonic acid) diammonium salt (ABTS) with H2O2 at pH 7 and pH 6 respectively. Our study shows that Mn‐doped and undoped CDs do not feature peroxidase‐like properties at pH=7. The mechanism and kinetics of the peroxidase‐mimicking reaction of Cu‐CDs were investigated by spectroscopic studies. Moreover, colorimetric sensing of different antioxidants was monitored based on the reduction of oxidized TMB, with selective detection of ascorbic acid in the range of ∼2–1000 μM with a limit of detection of 23.3 μM. This work introduces a facile strategy for synthesizing metal‐doped CDs with promising applications in biosensing and catalysis.

Noble-metal-free single-phase Co3V2O8with the structural integrity of nanofibers for the selective detection of ascorbic acid

Single-phase Co3V2O8with the structural integrity of nanofiber exhibits high electrocatalytic activity for the oxidation of ascorbic acid (AA).

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.