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Self-Assembled Peptide Nanostructures for Photoelectrochemical Bioanalysis Application: A Proof-of-Concept Study
摘要： Currently, one of important research directions of photo-electrochemical (PEC) bioanalysis is to exploit innovative photoactive species and their elegant implementations for selective detection and signal transduction. Different from existing candidates for photoelectrode development, this study, exemplified by the cationic dipeptide nanoparticles (CDNPs), reports the first demonstration of self-assembled peptide nanostructures (SAPNs) for the PEC bioanalysis. Specifically, the CDNPs were prepared as representative materials and then immobilized onto the indium tin oxide (ITO) electrode for the PEC differentiation of several commonly involved biomolecules such as ascorbic acid (AA) and L-cysteine. Significantly, the experimental results disclosed that the CDNPs possessed unique photocathodic responses and good analytical performance toward AA detection in terms of rapid response, high stability, and excellent selectivity. This work demonstrates the great potential of the large SAPN family for the future PEC bioanalysis development and has not been reported to our knowledge.
关键词： ascorbic acid detection,photoelectrochemical bioanalysis,cationic dipeptide nanoparticles,self-assembled peptide nanostructures
更新于2025-09-16 10:30:52
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Detection of Ascorbic Acid Using Green Synthesized Carbon Quantum Dots
摘要： 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.
关键词： electrochemical sensor,selective detection,ascorbic acid,carbon quantum dots,microwave irradiation
更新于2025-09-16 10:30:52
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Blue LED light irradiation enhances L-ascorbic acid content while reducing reactive oxygen species accumulation in Chinese cabbage seedlings
摘要： Chinese cabbage is one of the most representative vegetables in Southeast Asia and a main source of L-Ascorbic acid (AsA) for the human diet. In this study, we applied di?erent light qualities (red, blue and white) supported by light-emitting diode (LED) device to enhance AsA content in Chinese cabbage (Brassica rapa ssp. pekinensis) seedlings. Based on our results, blue LED light irradiation with an intensity of 125 μmol m?2s?1 increased the AsA content of ?ve-day-grown Chinese cabbage seedlings by 40% compared with white LED light irradiation. Accordingly, blue LED light irradiation induced expression of the AsA biosynthetic- and recycling-related genes. Interestingly, the reactive oxygen species (ROS) content of Chinese cabbage seedlings was decreased by blue LED light irradiation. In addition, the technology improving AsA content by blue LED light irradiation was applicable to other edible vegetable sprouts as well as to Chinese cabbage sprouts. Conclusively, our report introduces a source technology for arti?cially improving the AsA content of Chinese cabbage seedlings by applying blue LED light, which implies that application of certain types of LED light enables on-purpose cultivation of crops.
关键词： Chinese cabbage,Blue light,Ascorbic acid (AsA),Light-emitting diode (LED),Antioxidant
更新于2025-09-12 10:27:22
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Nutrient Levels in Brassicaceae Microgreens Increase Under Tailored Light-Emitting Diode Spectra
摘要： To increase the nutritional value and levels of essential minerals in vegetable food, microgreens are promising targets. The metabolic processes of microgreens can be managed with different cultivation techniques, which include manipulating the properties of light derived by light-emitting diodes (LEDs). In this study Brassicaceae microgreens (kohlrabi Brassica oleracea var. gongylodes, broccoli Brassica oleracea, and mizuna Brassica rapa var. Japonica) were cultivated under different light spectral quality, and the metabolic changes insoluble sugars (hexoses and sucrose), ascorbic acid, β-carotene, and contents of non-heme iron (Fe) and its connection with magnesium (Mg) or calcium (Ca) levels were monitored. Plants grew under the primary LED light spectrum (the combination of blue light at 447 nm, red at 638 and 665 nm, and far-red at 731 nm) or supplemented with LED green light at 520 nm, yellow at 595 nm, or orange at 622 nm. The photoperiod was 16 h, and a total PPFD of 300 μmol m-2 s-1 was maintained. Under supplemental yellow light at 595 nm, the content of soluble carbohydrates increased significantly in mizuna and broccoli. Under all supplemental light components, β-carotene accumulated in mizuna, and ascorbic acid accumulated significantly in kohlrabi. Under supplemental orange light at 622 nm, Fe, Mg, and Ca contents increased significantly in all microgreens. The accumulation of Fe was highly dependent on promoters and inhibitors of Fe absorption, as demonstrated by the very strong positive correlations between Fe and Ca and between Fe and Mg in kohlrabi and broccoli, and the strong negative correlations between Fe and β-carotene and between Fe and soluble carbohydrates in kohlrabi. Thus, the metabolic changes that occurred in treated microgreens led to increases in the contents of essential nutrients. Therefore, selected supplemental LED wavelengths can be used in the cultivation of Brassicaceae microgreens to preserve and increase the contents of specific nutritionally valuable metabolites.
关键词： microgreens,Brassicaceae,carbohydrates,β-carotene,ascorbic acid,mineral elements,light-emitting diodes
更新于2025-09-11 14:15:04
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Study of Bi-directional detection for ascorbic acid and sodium nitrite based on Eu-containing luminescent polyoxometalate
摘要： Eu-containing polyoxometalate K13Eu(SiMoW10O39)2·28H2O (Eu-SiMoW) owns the stimu-chromic and photo-luminescence properties. An ingenious test of ascorbic acid (AA) and sodium nitrite (NaNO2) was carried out based on the dual properties of Eu-SiMoW in solutions. First, the redox reaction of Eu-SiMoW and AA generated the blue reduced Eu-SiMoW, accompanied by fluorescence quenching; then the redox reaction of the reduced Eu-SiMoW and NaNO2 made Eu-SiMoW back to its original pale yellow state with red luminescence. Accordingly, the content of AA and NaNO2 could be measured by the reversible change of color and luminescence of Eu-SiMoW. This bi-directional detection method is first discovered and proven to be a simple and effective method for the detection of AA and NaNO2. The proposed method exhibited a linear response range (LRR) from 0.1 to 0.9 mmol L?1 with a limit of detection (LOD) of 0.53 μmol L?1 in UV–vis spectra and 4.67 μmol L?1 in luminescence spectra for AA as well as a LRR from 0.05 to 0.4 mmol L?1 with a LOD of 1.16 μmol L?1 in UV–vis spectra and 5.39 μmol L?1 in luminescence spectra for NaNO2. Moreover, the fluorescence switching of Eu-SiMoW could be realized by reacting with reductant and oxidant through the redox reaction. The detection mechanism is considered as a fluorescence resonance energy transfer process between discolor component SiMoW and luminescence component Eu in Eu-SiMoW.
关键词： Ascorbic acid,Sodium nitrite,Bi-directional detection,Eu-polyoxometalate,Luminescence switching
更新于2025-09-10 09:29:36
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Investigating the electrochemical behaviour and detection of uric acid on ITO electrodes modified with differently doped N-graphene films
摘要： Sensitive and selective electrochemical sensors based on indium-doped tin oxide electrodes (ITO) modified with differently nitrogen-doped graphene (NGr) films were successfully developed for the individual and simultaneous determination of uric acid (UA) in the presence of ascorbic acid (AA). The influence of the contents of various N-configurations on the detection of UA on the NGr/ITO based sensors is herein reported for the first time. The contents of various N-configurations on the NGr/ITO electrodes displayed varying promotional effects of the electro-oxidation of UA; attributed to the unique properties of the NGr films arising from the N-configurations. In particular, three N-doped materials prepared with varying amount of graphitic-N, pyrrolic-N, and pyridinic-N allowed the individual detection of UA, in the presence of AA, in the concentration range from 2-320 μM with the detection limits of 0.043 μM to 0.19 μM. Finally, the NGr/ITO-based sensors exhibited successful simultaneous detection of UA and AA, depicting detection limits of 0.051 - 0.19 μM and 0.93 – 5.1 μM within the concentration ranges of 6 - 280 μM and 8 – 800 μM, for the detection of UA and AA, respectively. The study provided insight into an understanding as to how the different contents of N-configurations influenced the electrocatalytic activity of NGr/ITO electrodes for the individual and simultaneous detection of uric acid.
关键词： nitrogen-doped graphene,uric acid,indium-doped tin oxide,ascorbic acid,electrochemical sensors
更新于2025-09-09 09:28:46
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Light regulation of vitamin C in tomato fruit is mediated through photosynthesis
摘要： Higher levels of irradiance result in higher accumulation of ascorbate in leaves and fruits. Photosynthesis and respiration are an integral part of the physiological mechanism of light regulation of ascorbate in leaves, but little is known about the light regulation of ascorbate in fruit. The aim of this study was to investigate whether fruit illumination alone is sufficient for ascorbate increase in tomato fruit and whether this light signal is mediated by respiration and photosynthesis. First the changes of ascorbate with the progress of fruit development were investigated and subsequently detached fruit of different tomato genotypes were exposed to different irradiances and spectra. Measurements were performed on ascorbate, respiration, photosynthesis and chlorophyll content of the fruit. When attached to the plant, there was no effect of development on ascorbate from the mature green to the red stage. Detached fruit stored in darkness did not accumulate ascorbate. However, when exposed to 300-600 μmol m-2 s-1 light detached mature green fruit (photosynthetically active) substantially accumulated ascorbate, while mature red fruit (non-photosynthetically active) did not respond to light. Photosynthesis correlated with this increase of ascorbate while no correlation between respiration and ascorbate was found. Spectral effects on ascorbate in detached tomato fruit were limited. These results indicate that the signal for light regulation of ascorbate is perceived locally in the fruit and that fruit illumination alone is sufficient for a considerable increase in ascorbate levels for as long as the fruit contains chlorophyll. It is shown that photosynthetic activity of the fruit is an integral part of the response of ascorbate to light in tomato fruit. The light induced increase in ascorbate levels occurred in a range of genotypes, indicating a universal effect of light to ascorbate in tomato fruit.
关键词： photosynthesis,respiration,vitamin C,irradiance,ascorbic acid,spectrum
更新于2025-09-04 15:30:14