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S, N co-doped graphene quantum dots-induced ascorbic acid fluorescent sensor: Design, characterization and performance
摘要： In this work, new detection route for ascorbic acid was designed. First, highly luminescent sulfur and nitrogen doped graphene quantum dots (S,N-GQDs) were prepared via simple hydrothermal method using citric acid and thiourea as the C, N and S sources respectively. The prepared S,N-GQDs are characterized by XRD, HRTEM, FTIR, EDS and PL. Investigations showed that prepared S,N-GQDs have a good photostability and excitation-dependent emission fluorescence. Prepared S,N-GQDs showed maximum excitation wavelength and emission wavelength at 400 and 462nm, respectively. In the following, prepared S,N-GQDs were applied as a photoluminescence probe for detection of ascorbic acid (AA). The designed sensor was based on “off-on” detection mode. The developed sensor had a linear response to AA over a concentration range of 10-500μM with a detection limit of 1.2μM. The regression equation is Y = 0.0014 X+1.2036, where Y and X denote the fluorescence peak intensity and AA concentration, respectively.
关键词： Graphene quantum dots,Quantum confinement,Fluorescence sensor,Nanostructures,Water-soluble vitamin,Quenching
更新于2025-11-14 15:32:45
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Abiotic reductive deiodination of iodinated organic compounds and X-ray contrast media catalyzed by free corrinoids
摘要： Iodinated X-ray contrast media are known for their stability concerning deiodination in the aquatic environment under aerobic conditions. In this study, we demonstrate the abiotic reductive deiodination of the iodinated contrast media iopromide, iopamidol and diatrizoate in the presence of corrinoids. In addition, triiodinated benzoic acid derivatives with iodine atoms bound at different positions were investigated. Corrinoids like cyanocobalamin (vitamin B12) and dicyanocobinamide served as electron shuttles and as catalysts between the reducing agent (e.g., titanium (III) citrate) and the electron accepting iodinated compound. The concentration decrease of the iodinated compounds followed first-order kinetics with rate constant kobs depending on the iodinated compound. A linear correlation between the rate of iodide release and the corrinoid concentration was observed, with deiodination rates for dicyanocobinamide twice as high as for vitamin B12. Reducing agents with a less negative standard redox potential like dithiothreitol or cysteine caused slower deiodination as the cobalt center was only reduced to its CoII oxidation state. With a temperature increase from 11 to 23 °C, the concentrations of released iodide doubled. A complete deiodination was only observed for the iodinated contrast media but not for structurally similar iodinated benzoic acid derivatives.
关键词： Vitamin B12,X-ray contrast media,Abiotic,Deiodination,Bank filtration,Corrinoids
更新于2025-09-23 15:22:29
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Vitamin C Determination by Ultraviolet Spectroscopy and Multiproduct Calibration
摘要： In this work the vitamin C was determined in industrialized nectar juices through ultraviolet (UV) spectroscopy and multiproduct multivariate calibration, based on partial least squares (PLS) regression. Since samples with different flavors, sugar content (light or not) were together in the model construction, it can be considered as a multiproduct and, due to the heterogeneity of the samples, it was necessary to optimize the calibration and validation sets by outliers elimination. The model was developed and validated by the evaluation of the figures of merit such as: accuracy, sensitivity, analytical sensitivity, adjust, linearity, relative prediction deviation, limits of detection and quantification, indicating that the multiproduct model developed from UV spectroscopy and PLS regression can be used in the industrial routine analysis as an alternative to titration or other time and reagent consuming methods. Here, it was evidenced that the UV-PLS multiproduct model provides advantages as being free of sample preparation steps, is suitable to be updated in order to measure other parameters, does not generates residues and is feasible to be implemented for on-line monitoring. Furthermore, the application of multivariate calibration in multiproduct models is extremely attractive from the industrial point of view.
关键词： multiproduct calibration,vitamin C,PLS,UV spectroscopy
更新于2025-09-23 15:21:21
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Graphene quantum dot-gold hybrid nanoparticles integrated aptasensor for ultra-sensitive detection of vitamin D3 towards point-of-care application
摘要： Vitamin D is a sunshine vitamin required by the body for various physiological activities. Deficiency of vitamin D (≤ 29 ng mL-1) can cause dental diseases, sarcopenia, osteoporosis, depression, type 2 diabetes, cancer, etc. Additionally, elevated levels of vitamin D (>150 ng mL-1) can result in numerous infirmities such as anorexia, irregular heartbeat, hypercalcemia, fatigue, etc. Hence, periodic detection can help maintain an appropriate level (≥ 30 ng mL-1) of vitamin D in blood serum. Conventional techniques used for the detection of vitamin D are expensive, time consuming, require skilled work force and a specialised laboratory. Herein, we report a portable electrochemical aptasensor for the detection of vitamin D3 using graphene quantum dot-gold (GQD-Au) hybrid nanoparticles. The developed aptasensor has a linear range of 1 nM – 500 nM, limit of detection (LOD) of 0.70 nM (0.28 ng mL-1), limit of quantification (LOQ) of 2.09 nM (0.84 ng mL-1), sensitivity of 0.90 Ω nM-1 mm-2 and a response time <1 minute. The sensor shows high specificity towards vitamin D3, a good stability, shelf life of over 35 days and nearly 98% recovery with serum samples. The developed sensor has been integrated with controlled electronics, thus establishing a portable prototype.
关键词： electrochemical,graphene quantum dot-gold hybrid,aptasensor,Vitamin D3,nanoparticles
更新于2025-09-23 15:21:01
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Evaluation of a Ultraviolet B Light Emitting Diode (LED) for Producing Vitamin D <sub/>3</sub> in Human Skin
摘要： Aim: A commercially available light emitting diode (LED) that transmitted narrow band ultraviolet B (UVB) radiation was evaluated for its efficacy and efficiency to produce vitamin D3 in human skin. Materials and Methods: Human skin samples were obtained from surgical procedures. The LED had peak emission wavelength of 295 nm. Skin samples were exposed to the UVB-LED for varying times and then were analyzed by high-pressure liquid chromatography (HPLC) to determine the vitamin D3 content. Results: There was a statistically significant time- and dose- dependent increase in the percent of 7-dehydrocholesterol that was converted to vitamin D3 in the skin type II samples; 1.3%±0.5, 2.3%±0.6 and 4.5%±1.67 after exposure to 0.75 (11.7 mJ/cm2), 1.5 (23.4 mJ/cm2) and 3 (46.8 mJ/cm2) minimal erythemal doses (MEDs), respectively. Conclusion: The UVB-LED was effective and efficient in generating vitamin D3 in human skin, in vitro. The amount of vitamin D3 production increased in a dose-dependent fashion with increased UVB energy. UVB-LEDs can be developed for devices that can efficiently produce vitamin D3 in human skin.
关键词： vitamin D3,human skin,ultraviolet B radiation,Previtamin D3,ultraviolet radiation light emitting diode (LED)
更新于2025-09-23 15:21:01
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A new parameterization of the UV irradiance altitude dependence for clear-sky conditions and its application in the on-line UV tool over Northern Eurasia
摘要： A new method for calculating the altitude UV dependence is proposed for different types of biologically active UV radiation (erythemally-weighted, vitamin-D-weighted and cataract-weighted types). We show that for the specified groups of parameters the altitude UV amplification (AUV) can be presented as a composite of independent contributions of UV amplification from different factors within a wide range of their changes with mean uncertainty of 1% and standard deviation of 3% compared with the exact model simulations with the same input parameters. The parameterization takes into account for the altitude dependence of molecular number density, ozone content, aerosol and spatial surface albedo. We also provide generalized altitude dependencies of the parameters for evaluating the AUV. The resulting comparison of the altitude UV effects using the proposed method shows a good agreement with the accurate 8-stream DISORT model simulations with correlation coefficient r>0.996. A satisfactory agreement was also obtained with the experimental UV data in mountain regions. Using this parameterization we analyzed the role of different geophysical parameters in UV variations with altitude. The decrease in molecular number density, especially at high altitudes, and the increase in surface albedo play the most significant role in the UV growth. Typical aerosol and ozone altitude UV effects do not exceed 10-20%. Using the proposed parameterization implemented in the on-line UV tool (http://momsu.ru/uv/) for Northern Eurasia over the PEEX domain we analyzed the altitude UV increase and its possible effects on human health considering different skin types and various open body fraction for January and April conditions in the Alpine region.
关键词： UV radiation,altitude dependence,RT modelling,cataract-weighted irradiance,erythemally-weighted irradiance,vitamin D-weighted irradiance,interactive UV-tool
更新于2025-09-23 15:21:01
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Effect of a topical antioxidant serum containing vitamin C, vitamin E, and ferulic acid after Qa??switched 1064a??nm Nd:YAG laser for treatment of environmenta??induced skin pigmentation
摘要： Background: Extrinsic skin aging caused by atmospheric pollutants is associated with a sustained inflammatory response which is a significant risk factor for lentigines and melasma. Aims: The aim of this study was to evaluate the efficacy of topical application of combination formulation of vitamin C, vitamin E, and ferulic acid as an adjuvant to Q-switched Nd:YAG (QSNY) lasers treatment in individuals with lentigines and melasma. Methods: A single blinded, prospective, randomized split-face trial was conducted. Eighteen men and women between 26 and 53 years old were treated with a combination antioxidant serum on one randomized side of their face immediately after QSNY laser and twice daily for 2 weeks. Patients were evaluated using digital photography and spectrometry to assess the melanin index and erythema index. Melasma severity score and global improvement scores also were assessed. Results: The treated side of the face exhibited a significantly greater reduction in the melanin index. There was no significant difference in post-treatment erythema. More clinical improvement was observed on the treated side compared with the untreated side. Conclusions: Our study suggests that topical application of a combination vitamins C, E, and ferulic acid antioxidant formula may be effective as an adjuvant option in QSNY lasers.
关键词： air pollution,lentigo,QS Nd:YAG laser,vitamin C,antioxidant
更新于2025-09-23 15:19:57
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Heterostructures of mesoporous TiO2 and SnO2 nanocatalyst for improved electrochemical oxidation ability of Vitamin B6 in pharmaceutical tablets
摘要： The detection of water soluble vitamins using electrochemical method is widely established in pharmaceutical quality control laboratories, and especially the recent advances in hybrid heterostructure nanomaterials has devoted to enhance the significant analytical parameters like sensitivity, selectivity and fast response time. Herein, we report the synthesis of a hybrid heterostructure comprising SnO2 nanoparticles supported mesoporous TiO2, and the obtained nanocomposite were fabricated over glassy carbon electrode (GCE) for the electrochemical oxidation of vitamin B6 in pharmaceutical tablets. The designed SnO2-TiO2/GC modified electrode exhibits well-defined oxidation peak with lowering over-potential and larger signal response compared to the pristine counterparts, and it is mainly due to the formation of abundant active surface layer offered by SnO2 cocatalyst, and thus significantly enhances the electrochemical surface area. Differential pulse voltammetry (DPV) measurements revealed a sharp increase in the anodic peak current upon addition of increasing concentration of vitamin B6. The analytical performance of the modified electrode displayed a wide linear range (0.1 - 31.4 μM), high selectivity, and excellent sensitivity (759.73 μA mM-1 cm-2) with low detection limit (35 nM). Thus, the resultant mesoporous hybrid nanocatalyst provides an efficient electrochemical platform for determination of various potential analytes.
关键词： electrochemical sensor,Tin oxide (SnO2) cocatalyst,mesoporous,Titanium dioxide (TiO2),Vitamin B6
更新于2025-09-19 17:15:36
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Upgrading the photocatalytic achievement of g-C3N4 nanosheets along decoration with Ag@TiO2 nanospheres for the preparation of vitamin B3
摘要： In this investigation, synthesis of ternary heterojunctions made of g-C3N4 sheets decorated with Ag@TiO2 nanospheres was successfully achieved. The reaction was initially started by combustion routine adopting silica of mesoporous type as a template to fabricate mesoporous C3N4 of graphite-like structure. After that, g-C3N4 nanosheets were decorated with TiO2 nanospheres and then TiO2 nanospheres were doped with Ag. Ag@TiO2/g-C3N4 ternary heterojunctions having 140 m2 g?1 specific surface area were produced. The resultant heterojunctions acquired a limited bandgap (2.26 eV) in addition to 3.4 nm pore size. The resultant Ag@TiO2/g-C3N4 nanocomposites were tested applying the photo-catalytic preparation of vitamin B3. It was observed that vitamin B3 could be synthesized adopting mesoporous Ag@TiO2/g-C3N4 ternary heterojunctions with a higher rate (33 times) than that when pristine TiO2 was adopted. The greater photo-catalytic action of the synthesized heterojunction might be correlated to the favorable Vis light absorption as well as the large separation between es and positive holes produced from inclusion of Ti3+ self-doping. In addition, huge amount of active sites was offered owing to the mesoporous network nature of the resultant heterojunctions. Finally, the dopant Ag nanoparticles positively supported the photocatalytic activity by its surface plasma resonance effect.
关键词： Ag@TiO2/g-C3N4 ternary heterojunctions,Vitamin B3,Visible photocatalyst
更新于2025-09-19 17:15:36
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Effects of ultraviolet irradiation with a LED device on bone metabolism associated with vitamin D deficiency in senescence-accelerated mouse P6
摘要： Aims: This study investigated effects of narrow-range ultraviolet irradiation (UVR) by a new UV–LED device on vitamin D supply and changes of bone in senescence-accelerated mouse P6 (SAMP6) with vitamin D deficiency. Main methods: We used female SAMP6 mice as a senile osteoporotic model. We set a total of 3 groups (n ? 4 per group); D-UVRt group (vitamin D deficient–dietary and UVR), D- (vitamin D deficient–dietary), and Dt groups (vitamin D contained–dietary). Mice in the D-UVR t group were UV–irradiated (305nm) with 1 kJ/m2 twice a week for 12 weeks from 20 to 32 weeks of age. Serum 25(OH)D, 1,25(OH)2D, and micro–computed tomography (CT) were assessed over time. Mechanical test, and histological assay were performed for femurs removed at 32 weeks of age. Key findings: UVR increased both serum 25(OH)D and 1,25(OH)2D levels at 4 and 8 weeks–UVR in the D-UVRt group compared with that in the D- group (P < 0.05, respectively). Relative levels of trabecular bone mineral density in micro–CT were higher in the D-UVRt group than in the D- group at 8 weeks–UVR (P ? 0.048). The ultimate load was significantly higher in the D-UVRt group than in the D- group (P ? 0.036). In histological assay, fewer osteoclasts and less immature bone (/mature bone) could be observed in the D-UVRt group than in the D- group, significantly. Significance: UVR may have possibility to improve bone metabolism associated with vitamin D deficiency in SAMP6 mice.
关键词： Vitamin D,Musculoskeletal system,Osteoporosis,Pathology,Endocrinology,Metabolism,Bone mineral density,LED,Physiology
更新于2025-09-19 17:13:59