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Keun-hyeung Lee - One of the best experts on this subject based on the ideXlab platform.

  • Selective and Sensitive Detection of Heavy Metal Ions in 100% Aqueous Solution and Cells with a Fluorescence Chemosensor Based on Peptide Using Aggregation-Induced Emission
    Analytical Chemistry, 2016
    Co-Authors: Lok Nath Neupane, Heon Joo Park, Keun-hyeung Lee
    Abstract:

    A fluorescent peptidyl chemosensor for the detection of heavy metal ions in aqueous solution as well as in cells was synthesized on the basis of the peptide receptor for the metal ions using an aggregation-induced emission fluorophore. The peptidyl chemosensor (1) bearing tetraphenylethylene fluorophore showed an exclusively selective turn-on response to Hg2+ among 16 metal ions in aqueous buffered solution containing NaCl. The peptidyl chemosensor complexed Hg2+ ions and then aggregated in aqueous buffered solution, resulting in the significant enhancement (OFF-On) of emissions at around 470 nm. The fluorescent sensor showed a highly sensitive response to Hg2+, and about 1.0 equiv of Hg2+ was enough for the saturation of the emission intensity change. The detection limit (5.3 nM, R2 = 0.99) of 1 for Hg2+ ions was lower than the Maximum Allowable Level of Hg2+ in drinking water by EPA. Moreover, the peptidyl chemosensor penetrated live cells and detected intracellular Hg2+ ions by the turn-on response.

  • Highly sensitive and selective detection of Al(III) ions in aqueous buffered solution with fluorescent peptide-based sensor.
    Bioorganic & Medicinal Chemistry Letters, 2016
    Co-Authors: Gi Won Hwang, Keun-hyeung Lee
    Abstract:

    Abstract A fluorescent sensor based on a tripeptide (SerGluGlu) with a dansyl fluorophore detected selectively Al(III) among 16 metal ions in aqueous buffered solutions without any organic cosolvent. The peptide-based sensor showed a highly sensitive turn on response to aluminium ion with high binding affinity (1.84 × 104 M−1) in aqueous buffered solutions. The detection limit (230 nM, 5.98 ppb) of the peptide-based sensor was much lower than the Maximum Allowable Level (7.41 μM) of aluminium ions in drinking water demanded by EPA. The binding mode of the peptide sensor with aluminium ions was characterized using ESI mass spectrometry, NMR titration, and pH titration experiments.

  • Efficient ensemble system based on the copper binding motif for highly sensitive and selective detection of cyanide ions in 100% aqueous solutions by fluorescent and colorimetric changes.
    Analytical Chemistry, 2015
    Co-Authors: Kwan Ho Jung, Keun-hyeung Lee
    Abstract:

    A peptide-based ensemble for the detection of cyanide ions in 100% aqueous solutions was designed on the basis of the copper binding motif. 7-Nitro-2,1,3-benzoxadiazole-labeled tripeptide (NBD-SSH, NBD-SerSerHis) formed the ensemble with Cu2+, leading to a change in the color of the solution from yellow to orange and a complete decrease of fluorescence emission. The ensemble (NBD-SSH–Cu2+) sensitively and selectively detected a low concentration of cyanide ions in 100% aqueous solutions by a colorimetric change as well as a fluorescent change. The addition of cyanide ions instantly removed Cu2+ from the ensemble (NBD-SSH–Cu2+) in 100% aqueous solutions, resulting in a color change of the solution from orange to yellow and a “turn-on” fluorescent response. The detection limits for cyanide ions were lower than the Maximum Allowable Level of cyanide ions in drinking water set by the World Health Organization. The peptide-based ensemble system is expected to be a potential and practical way for the detection ...

  • Recyclable Hypersensitive Fluorescent Dipeptidyl Chemosensor Based on Silica Nanoparticles Using Signal Amplification for the Detection of Hg(II) and Cu(II) in Aqueous Solutions
    Bulletin of The Korean Chemical Society, 2015
    Co-Authors: Songyi Han, Kwan Ho Jung, Lok Nath Neupane, Ponnaboina Thirupathi, Keun-hyeung Lee
    Abstract:

    Silica nanoparticles (SiNPs) were synthesized for the detection of heavy metal ions by conjugating a dipeptidyl fluorescent chemosensor (DPN) into the SiNPs using a click reaction. Among the 14 metal ions tested, SiNPs conjugated with DPN (DPNSi) showed sensitive responses toward Hg(II) and Cu(II) ions in aqueous solutions. The detection limits of DPNSi were determined to be 3.8 and 16.5 nM for Hg(II) and Cu(II) ions, respectively, in aqueous solutions. Moreover, the sensitivity of DPNSi to Hg(II) ions was significantly higher than that of DPN. DPNSi was sufficiently sensitive for monitoring the Maximum Allowable Level of Hg(II) and Cu(II) ions in drinking water demanded by the Environmental Protection Agency (EPA). DPNSi could be recycled for the detection and removal of toxic mercury ions in aqueous solutions by regeneration with glutathione.

  • Highly sensitive colorimetric detection of HgII and CuII in aqueous solutions: from amino acids toward solid platforms
    The Analyst, 2015
    Co-Authors: Joo-young Park, Lok Nath Neupane, Keun-hyeung Lee
    Abstract:

    A chemosensor (NBD-H) based on an amino acid with 7-nitro-2,1,3-benzoxadiazole was used for selective detection of HgII and CuII among 15 metal ions in aqueous solutions by a colorimetric change. NBD-H sensitively differentiated HgII and CuII in aqueous solutions by a color change; a pink color for HgII and an orange color for CuII. NBD-H showed nanomolar detection limits for HgII (176 nM, R2 = 0.996) and CuII (163 nM, R2 = 0.996). The detection limit for CuII was much lower than the Maximum Allowable Level of CuII in drinking water recommended by the U.S. EPA. The binding mode study showed that deprotonation of the NH group of NBD-H played a critical role in the binding and sensing of metal ions. NBD-H immobilized on PEG-PS resin maintained the potent binding affinity and sensing ability for the metal ions. The resin with NBD-H was recyclable for the detection of metal ions in 100% aqueous solutions.

Tzi Bun Ng - One of the best experts on this subject based on the ideXlab platform.

  • boletus edulis nitrite reductase reduces nitrite content of pickles and mitigates intoxication in nitrite intoxicated mice
    Scientific Reports, 2015
    Co-Authors: Weiwei Zhang, Guoting Tian, Shanshan Feng, John Wong, Yongchang Zhao, Xiao Chen, Hexiang Wang, Tzi Bun Ng
    Abstract:

    Pickles (picked vegetables), a traditional dish favored by many Chinese, are mildly salted and lactic acid-fermented vegetables in China. During pickle fermentation, vegetables are immersed in a 6–8% salt solution and left to undergo lactic acid fermentation for 4–10 days at different temperatures. Lactobacillus produced or added during this fermented process is known to be beneficial to human health1. These bacteria contribute to the homeostasis of the microbial environment in the intestinal tract and maintain intestinal health. Metabolic activities of Lactobacillus during fermentation produces lactic acid, folic acid and vitamins which boost the human immune system. In addition, pickles exert the health-promoting effects of producing weight loss and preventing myocardial infarction and atherosclerosis. On the other hand, nitrite which deleteriously affects health is inevitably produced as a result of fermentation during the course of pickle production. Nitrite is a strong oxidizing agent. It oxidizes ferrous hemoglobin which transports oxygen in the blood to ferric hemoglobin. As a consequence, hemoglobin loses its oxygen transport capability leading to hypoxia2,3,4,5. In the acidic environment produced by gastric acid, nitrite is converted into carcinogenic nitrosamine6,7. Hence, the presence of nitrite in pickles is a bottleneck which limits further development of the pickle industry. More and more attention is drawn to the problem of the presence of nitrite in pickles, now that there is increased awareness of people about food safety. The National Food Safety Department in China has developed a standard for regulating the Levels of nitrite and nitrate in vegetables and their products. According to the national food safety standard in China regarding the Maximum Allowable Level of contaminant in food (GB2762-2005), the nitrite content in preserved vegetables should not exceed 20 mg/kg sample. The mushroom Boletus edulis is well known for being delicious and nutritious. The crispy fruiting bodies can be sliced and eaten raw. When the mushroom is used to prepare soup, it gives off a pleasant fragrant smell. B. edulis is also nutritious because of the abundance of amino acids, polysaccharides and vitamins. Reports on its antitumor and antioxidant activities have recently been published8,9,10,11,12. In our investigation, it was disclosed that the fruiting bodies of B. edulis were capable of eliciting a marked reduction of the nitrite content in pickles. Hence we added the fruiting bodies during the process of pickle production and investigated the effect on nitrite content in pickles. This provides a new approach and technology for lowering the nitrite content in pickles.

Vanhaecke Frank - One of the best experts on this subject based on the ideXlab platform.

  • Tracing Mercury Pollution along the Norwegian Coast via Elemental, Speciation, and Isotopic Analysis of Liver and Muscle Tissue of Deep-Water Marine Fish (Brosme brosme)
    2019
    Co-Authors: Rua-ibarz Ana, Bolea-fernandez Eduardo, Måge Amund, Frantzen Sylvia, Sanden Monica, Vanhaecke Frank
    Abstract:

    Liver and muscle tissue of tusks (Brosme brosme) have been analyzed for their THg and MeHg concentrations and Hg isotopic signatures for tracing Hg pollution along the Norwegian coast. Clear differences between tissue types and locations were established. At five of the eight locations, the Hg concentration in muscle exceeded the Maximum Allowable Level of 0.5 mg kg–1 wet weight. δ202Hg values in both tissue types indicated that Hg speciation affects the bulk Hg isotopic signature. Tusk liver seems to be more sensitive to immediate changes and to anthropogenic inorganic Hg, while the muscle rather reflects the Hg accumulated over a longer period of exposure. The δ202Hg values of liver and muscle also enabled different sources of Hg and exposure pathways to be distinguished. δ202Hgmuscle–δ202Hgliver showed a clear correlation with the % MeHg in tusk liver for the coastal waters, but not for the fjords. The absence of significant differences in Δ199Hg values between both tissues of tusk from the same location suggests that in vivo metabolic processes are the underlying reason for the differences in Hg speciation and in δ202Hg values. This work highlights the importance of selecting different tissues of marine fish in future Hg monitoring programs

  • Tracing Mercury Pollution along the Norwegian Coast via Elemental, Speciation, and Isotopic Analysis of Liver and Muscle Tissue of Deep-Water Marine Fish (Brosme brosme)
    2019
    Co-Authors: Rua-ibarz Ana, Bolea-fernandez Eduardo, Måge Amund, Frantzen Sylvia, Sanden Monica, Vanhaecke Frank
    Abstract:

    Liver and muscle tissue of tusks (Brosme brosme) have been analyzed for their THg and MeHg concentrations and Hg isotopic signatures for tracing Hg pollution along the Norwegian coast. Clear differences between tissue types and locations were established. At five of the eight locations, the Hg concentration in muscle exceeded the Maximum Allowable Level of 0.5 mg kg–1 wet weight. δ202Hg values in both tissue types indicated that Hg speciation affects the bulk Hg isotopic signature. Tusk liver seems to be more sensitive to immediate changes and to anthropogenic inorganic Hg, while the muscle rather reflects the Hg accumulated over a longer period of exposure. The δ202Hg values of liver and muscle also enabled different sources of Hg and exposure pathways to be distinguished. δ202Hgmuscle–δ202Hgliver showed a clear correlation with the % MeHg in tusk liver for the coastal waters, but not for the fjords. The absence of significant differences in Δ199Hg values between both tissues of tusk from the same location suggests that in vivo metabolic processes are the underlying reason for the differences in Hg speciation and in δ202Hg values. This work highlights the importance of selecting different tissues of marine fish in future Hg monitoring programs.publishedVersio

Weiwei Zhang - One of the best experts on this subject based on the ideXlab platform.

  • boletus edulis nitrite reductase reduces nitrite content of pickles and mitigates intoxication in nitrite intoxicated mice
    Scientific Reports, 2015
    Co-Authors: Weiwei Zhang, Guoting Tian, Shanshan Feng, John Wong, Yongchang Zhao, Xiao Chen, Hexiang Wang, Tzi Bun Ng
    Abstract:

    Pickles (picked vegetables), a traditional dish favored by many Chinese, are mildly salted and lactic acid-fermented vegetables in China. During pickle fermentation, vegetables are immersed in a 6–8% salt solution and left to undergo lactic acid fermentation for 4–10 days at different temperatures. Lactobacillus produced or added during this fermented process is known to be beneficial to human health1. These bacteria contribute to the homeostasis of the microbial environment in the intestinal tract and maintain intestinal health. Metabolic activities of Lactobacillus during fermentation produces lactic acid, folic acid and vitamins which boost the human immune system. In addition, pickles exert the health-promoting effects of producing weight loss and preventing myocardial infarction and atherosclerosis. On the other hand, nitrite which deleteriously affects health is inevitably produced as a result of fermentation during the course of pickle production. Nitrite is a strong oxidizing agent. It oxidizes ferrous hemoglobin which transports oxygen in the blood to ferric hemoglobin. As a consequence, hemoglobin loses its oxygen transport capability leading to hypoxia2,3,4,5. In the acidic environment produced by gastric acid, nitrite is converted into carcinogenic nitrosamine6,7. Hence, the presence of nitrite in pickles is a bottleneck which limits further development of the pickle industry. More and more attention is drawn to the problem of the presence of nitrite in pickles, now that there is increased awareness of people about food safety. The National Food Safety Department in China has developed a standard for regulating the Levels of nitrite and nitrate in vegetables and their products. According to the national food safety standard in China regarding the Maximum Allowable Level of contaminant in food (GB2762-2005), the nitrite content in preserved vegetables should not exceed 20 mg/kg sample. The mushroom Boletus edulis is well known for being delicious and nutritious. The crispy fruiting bodies can be sliced and eaten raw. When the mushroom is used to prepare soup, it gives off a pleasant fragrant smell. B. edulis is also nutritious because of the abundance of amino acids, polysaccharides and vitamins. Reports on its antitumor and antioxidant activities have recently been published8,9,10,11,12. In our investigation, it was disclosed that the fruiting bodies of B. edulis were capable of eliciting a marked reduction of the nitrite content in pickles. Hence we added the fruiting bodies during the process of pickle production and investigated the effect on nitrite content in pickles. This provides a new approach and technology for lowering the nitrite content in pickles.

Frank Vanhaecke - One of the best experts on this subject based on the ideXlab platform.

  • tracing mercury pollution along the norwegian coast via elemental speciation and isotopic analysis of liver and muscle tissue of deep water marine fish brosme brosme
    Environmental Science & Technology, 2019
    Co-Authors: Ana Ruaibarz, Eduardo Boleafernandez, Amund Maage, Sylvia Frantzen, Monica Sanden, Frank Vanhaecke
    Abstract:

    Liver and muscle tissue of tusks (Brosme brosme) have been analyzed for their THg and MeHg concentrations and Hg isotopic signatures for tracing Hg pollution along the Norwegian coast. Clear differences between tissue types and locations were established. At five of the eight locations, the Hg concentration in muscle exceeded the Maximum Allowable Level of 0.5 mg kg–1 wet weight. δ202Hg values in both tissue types indicated that Hg speciation affects the bulk Hg isotopic signature. Tusk liver seems to be more sensitive to immediate changes and to anthropogenic inorganic Hg, while the muscle rather reflects the Hg accumulated over a longer period of exposure. The δ202Hg values of liver and muscle also enabled different sources of Hg and exposure pathways to be distinguished. δ202Hgmuscle–δ202Hgliver showed a clear correlation with the % MeHg in tusk liver for the coastal waters, but not for the fjords. The absence of significant differences in Δ199Hg values between both tissues of tusk from the same locati...

  • Tracing Mercury Pollution along the Norwegian Coast via Elemental, Speciation, and Isotopic Analysis of Liver and Muscle Tissue of Deep-Water Marine Fish (Brosme brosme)
    2019
    Co-Authors: Ana Rua-ibarz, Amund Maage, Sylvia Frantzen, Monica Sanden, Eduardo Bolea-fernandez, Frank Vanhaecke
    Abstract:

    Liver and muscle tissue of tusks (Brosme brosme) have been analyzed for their THg and MeHg concentrations and Hg isotopic signatures for tracing Hg pollution along the Norwegian coast. Clear differences between tissue types and locations were established. At five of the eight locations, the Hg concentration in muscle exceeded the Maximum Allowable Level of 0.5 mg kg–1 wet weight. δ202Hg values in both tissue types indicated that Hg speciation affects the bulk Hg isotopic signature. Tusk liver seems to be more sensitive to immediate changes and to anthropogenic inorganic Hg, while the muscle rather reflects the Hg accumulated over a longer period of exposure. The δ202Hg values of liver and muscle also enabled different sources of Hg and exposure pathways to be distinguished. δ202Hgmuscle–δ202Hgliver showed a clear correlation with the % MeHg in tusk liver for the coastal waters, but not for the fjords. The absence of significant differences in Δ199Hg values between both tissues of tusk from the same location suggests that in vivo metabolic processes are the underlying reason for the differences in Hg speciation and in δ202Hg values. This work highlights the importance of selecting different tissues of marine fish in future Hg monitoring programs