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Yongkeun Park - One of the best experts on this subject based on the ideXlab platform.

  • measurements of complex refractive index change of photoactive yellow protein over a wide wavelength range using hyperspectral quantitative phase imaging
    Scientific Reports, 2018
    Co-Authors: Kyeoreh Lee, Hyotcherl Ihee, Young-min Kim, Jaehwang Jung, Yongkeun Park
    Abstract:

    A novel optical holographic Technique is presented to simultaneously measure both the real and imaginary components of the complex refractive index (CRI) of a protein solution over a wide visible wavelength range. Quantitative phase imaging was employed to precisely measure the optical field transmitted from a protein solution, from which the CRIs of the protein solution were retrieved using the Fourier Light Scattering Technique. Using this method, we characterized the CRIs of the two dominant structural states of a photoactive yellow protein solution over a broad wavelength range (461–582 nm). The significant CRI deviation between the two structural states was quantified and analysed. The results of both states show the similar overall shape of the expected rRI obtained from the Kramers–Kronig relations.

  • Measurements of complex refractive index change of photoactive yellow protein over a wide wavelength range using hyperspectral quantitative phase imaging
    NATURE PUBLISHING GROUP, 2018
    Co-Authors: Kyereh Lee, Hyotcherl Ihee, Young-min Kim, Jaehwang Jung, Yongkeun Park
    Abstract:

    A novel optical holographic Technique is presented to simultaneously measure both the real and imaginary components of the complex refractive index (CRI) of a protein solution over a wide visible wavelength range. Quantitative phase imaging was employed to precisely measure the optical field transmitted from a protein solution, from which the CRIs of the protein solution were retrieved using the Fourier Light Scattering Technique. Using this method, we characterized the CRIs of the two dominant structural states of a photoactive yellow protein solution over a broad wavelength range (461-582 nm). The significant CRI deviation between the two structural states was quantified and analysed. The results of both states show the similar overall shape of the expected rRI obtained from the Kramers-Kronig relations. © 2018 The Author(s

  • Measurements of complex refractive indices of photoactive yellow protein
    arXiv: Chemical Physics, 2015
    Co-Authors: Kyeoreh Lee, Hyotcherl Ihee, Young-min Kim, Jaehwang Jung, Yongkeun Park
    Abstract:

    A novel optical Technique for measuring the complex refractive index (CRI) of photoactive proteins over the wide range of visible wavelengths is presented. Employing quantitative phase microscopy equipped with a wavelength swept source, optical fields transmitted from a solution of photoactive proteins were precisely measured, from which the CRIs of the photoactive proteins were retrieved with the Fourier Light Scattering Technique. Using the present method, both the real and imaginary RIs of a photoactive yellow protein (PYP) solution were precisely measured over a broad wavelength range (461 - 582 nm). The internal population of the ground and excited states were switched by blue Light excitation (445 nm center wavelength), and the broadband refractive index increments of each state were measured. The significant CRI deviation between in the presence and absence of the blue excitation was quantified and explained based on the Kramers-Kronig relations.

  • static and dynamic Light Scattering of healthy and malaria parasite invaded red blood cells
    Journal of Biomedical Optics, 2010
    Co-Authors: Yongkeun Park, Monica Diezsilva, Dan Fu, Gabriel Popescu, Wonshik Choi, Ishan Barman, S Suresh, Michael S Feld
    Abstract:

    We present the Light Scattering of individual Plasmodium falciparum-parasitized human red blood cells Pf-RBCs, and demonstrate progressive alterations to the Scattering signal arising from the development of malaria-inducing parasites. By selectively imaging the electric fields using quantitative phase microscopy and a Fourier transform Light Scattering Technique, we calculate the Light Scattering maps of individual Pf-RBCs. We show that the onset and progression of pathological states of the Pf-RBCs can be clearly identified by the static Scattering maps. Progressive changes to the biophysical properties of the Pf-RBC membrane are captured from dynamic Light Scattering. © 2010 Society of Photo-Optical Instrumentation Engineers.

Zhanguang Chen - One of the best experts on this subject based on the ideXlab platform.

  • high sensitivity determination of curcumin in human urine using gemini zwitterionic surfactant as a probe by resonance Light Scattering Technique
    Phytochemical Analysis, 2012
    Co-Authors: Li Zhu, Jinbin Liu, Xi Chen, Shengwang Liang, Guomin Zhang, Zhanguang Chen
    Abstract:

    Introduction Curcumin is a popular plant medicine that is extracted from turmeric dry rhizomes of Curcuma longa Linn. The study of curcumin is well established and is currently becoming a centre of attention. Objective To develop a steady and simple assay for curcumin determination at the nanogram level based on the intense resonance Light Scattering (RLS) enhancement due to the interaction between curcumin and phosphodiesters quaternary ammonium salt (PQAS). Methodology PQAS, a new kind of Gemini zwitterionic surfactant, was used as the probe for the determination of curcumin by the RLS Technique. A series of validation experiments was also performed. Results A linear relationship was constructed between the ΔIRLS and the concentration of curcumin. The linear regression equation was presented as ΔIRLS = 8.37 + 44.92c (µg/mL) with the regression coefficient r = 0.9987 (n = 12) and the linear range was 0.08–60.0 µg/mL. The detection limit (3σ) was 2.6 ng/mL. Conclusion The proposed method can be used to detect the content of curcumin in human urine samples and this new assay using PQAS as a probe was more sensitive and displayed a wider linear range than that reported previously. Copyright © 2011 John Wiley & Sons, Ltd.

  • determination of antibacterial quaternary ammonium compound in lozenges and human serum by resonance Light Scattering Technique
    Journal of Pharmaceutical and Biomedical Analysis, 2008
    Co-Authors: Zhanguang Chen, Yurui Peng, Junhui Chen, Li Zhu
    Abstract:

    Abstract A method for the specific determination of an antibacterial quaternary ammonium compound Dequalinium chloride (DQC) was described in this paper. At pH 0.5, the resonance Light Scattering (RLS) intensity of sodium dodecyl benzene sulfonate (SDBS) remarkably was enhanced by adding DQC. A RLS peak at 392.0 nm was found, and the enhanced intensity of RLS at this wavelength was proportional to the concentration of DQC in the range of 0.096–2.88 μg/mL. The detection limit was 2.98 ng/mL and the correlation coefficient was r  = 0.9988 ( n  = 9). The method was applied to the analysis of DQC in lozenges and human serum. The results indicated that the method was sensitive, simple, practical and useful in the clinical assay.

  • a novel histidine assay using tetraphenylporphyrin manganese iii chloride as a molecular recognition probe by resonance Light Scattering Technique
    Analytica Chimica Acta, 2006
    Co-Authors: Zhanguang Chen, Jinbin Liu, Yali Han, Li Zhu
    Abstract:

    Abstract A novel histidine-selective method has been developed for the determination of histidine in aqueous solutions by resonance Light Scattering (RLS) Technique. At pH 8.0, the weak RLS intensity of tetraphenylporphyrin manganese (III) chloride [MnTPPCl] was greatly enhanced by the addition of histidine with the maximum peak located at 483 nm. Under the optimum conditions, it was found that the enhanced RLS intensity was in proportion to the concentration of histidine in the range 7.8 × 10 −7 –2.4 × 10 −5  mol l −1 . Low detection limit of 9.2 × 10 -8  mol l −1 has been achieved. The histidine concentrations in synthetic samples and real samples were determined with satisfactory results. The sensitivity and selectivity of this method are high enough to permit the determination of trace amounts of histidine without any significant interference from high levels of other components such as common anions and especially, other amino acids.

  • use of sodium lauroyl sarcosinate in a high sensitivity protein assay by resonance Light Scattering Technique
    Journal of Biomolecular Screening, 2006
    Co-Authors: Zhanguang Chen, Jinbin Liu, Yizeng Liang, Fenglian Ren
    Abstract:

    A simple and high-sensitivity method has been developed for the determination of proteins in aqueous solutions by resonance Light Scattering (RLS) Technique. At pH 3.4 and ionic strength 1.2 x 10(-3), the weak RLS intensity of sodium lauroyl sarcosinate was greatly enhanced by the addition of proteins with the maximum peak located at 391 nm. Under the optimum conditions, the enhanced RLS intensities were in proportion to the concentrations of proteins in the range of 0.04 to 2.1 microg/mL for lysozyme, 0.0025 to 1.2 microg/mL for bovine serum albumin, 0.0075 to 0.9 microg/mL for human serum albumin, 0.02 to 1.4 microg/mL for gamma-globulin, 0.02 to 0.8 microg/mL for egg albumin, and 0.01 to 0.6 microg/mL for hemoglobin. Low detection limits ranging from 0.8 ng/mL to 4.3 ng/mL depending on the kind of proteins that have been achieved. The protein concentrations in synthetic samples and real biochemical samples were determined with satisfactory results. This method presented here is not only sensitive and simple but also reliable and suitable for practical bioassay applications.

Golnaz Farhat - One of the best experts on this subject based on the ideXlab platform.

  • detecting apoptosis using dynamic Light Scattering with optical coherence tomography
    Journal of Biomedical Optics, 2011
    Co-Authors: Golnaz Farhat, Adrian Mariampillai, Victor X D Yang, Gregory J Czarnota, Michael C Kolios
    Abstract:

    A dynamic Light Scattering Technique is implemented using optical coherence tomography (OCT) to measure the change in intracellular motion as cells undergo apoptosis. Acute myeloid leukemia cells were treated with cisplatin and imaged at a frame rate of 166 Hz using a 1300 nm swept-source OCT system at various times over a period of 48 h. Time correlation analysis of the speckle intensities indicated a significant increase in intracellular motion 24 h after treatment. This rise in intracellular motion correlated with histological findings of irregularly shaped and fragmented cells indicative of cell membrane blebbing and fragmentation.

Shenyang Tong - One of the best experts on this subject based on the ideXlab platform.

  • determination for micro amounts of nucleic acids by a resonance Light Scattering Technique with dequalinium chloride
    Talanta, 2001
    Co-Authors: Shenyang Tong
    Abstract:

    Abstract Based on the strong enhancement effect of nucleic acids on resonance Light Scattering of dequalinium chloride, the determination method for micro amounts of nucleic acids has been developed. Under the experimental conditions (5.0×10−5 mol l−1 dequalinium, pH 7.0, at room temperature) the linear range of this assay is 0.04–10.0 μg ml−1 for calf thymus DNA and fish sperm DNA, and 0.04–35.0 μg ml−1 for yeast RNA. The detection limits (3σ) are 6.2 ng ml−1 for calf thymus DNA, 7.4 ng ml−1 for fish sperm DNA, and 7.0 ng ml−1 for yeast RNA, respectively. Almost no interference can be observed from ionic strength, proteins, nucleoside, and most of the metal ions. Six synthetic samples were determined satisfactorily.

  • determination of nucleic acids by a resonance Light Scattering Technique with α β γ δ tetrakis 4 trimethylammoniumyl phenyl porphine
    Analytical Chemistry, 1996
    Co-Authors: Cheng Zhi Huang, Shenyang Tong
    Abstract:

    The resonance Light-Scattering Technique, using a spectrofluorometer, was first developed as a sensitive instrumental analysis method. At pH 7.48 and ionic strength 0.004, the extent of Light-Scattering of α,β,γ,δ-tetrakis[4-(trimethylammoniumyl)phenyl]porphine (TAPP) is enhanced by nucleic acids near 432 nm. There are linear relationships between the enhanced extents of Light-Scattering and the concentrations of nucleic acids in the range of 1.8 × 10-7−10.8 × 10-7 M for calf thymus and fish sperm DNA and in the range of 1.8 × 10-7−1.8 × 10-6 M for yeast RNA. The limit of determination (3σ) is 4.1 × 10-8 M for calf thymus DNA, 4.6 × 10-8 M for fish sperm DNA, and 6.7 × 10-8 M for yeast RNA. Mechanism study indicates that nucleic acids react with the title porphyrin in two modes, depending on the concentrations of nucleic acids. When the molar ratio of nucleic acids to TAPP is smaller than 4:1, the hypochromicity and fluorescence quenching of TAPP by nucleic acids appear, and the enhancement of resonance l...

Li Zhu - One of the best experts on this subject based on the ideXlab platform.

  • high sensitivity determination of curcumin in human urine using gemini zwitterionic surfactant as a probe by resonance Light Scattering Technique
    Phytochemical Analysis, 2012
    Co-Authors: Li Zhu, Jinbin Liu, Xi Chen, Shengwang Liang, Guomin Zhang, Zhanguang Chen
    Abstract:

    Introduction Curcumin is a popular plant medicine that is extracted from turmeric dry rhizomes of Curcuma longa Linn. The study of curcumin is well established and is currently becoming a centre of attention. Objective To develop a steady and simple assay for curcumin determination at the nanogram level based on the intense resonance Light Scattering (RLS) enhancement due to the interaction between curcumin and phosphodiesters quaternary ammonium salt (PQAS). Methodology PQAS, a new kind of Gemini zwitterionic surfactant, was used as the probe for the determination of curcumin by the RLS Technique. A series of validation experiments was also performed. Results A linear relationship was constructed between the ΔIRLS and the concentration of curcumin. The linear regression equation was presented as ΔIRLS = 8.37 + 44.92c (µg/mL) with the regression coefficient r = 0.9987 (n = 12) and the linear range was 0.08–60.0 µg/mL. The detection limit (3σ) was 2.6 ng/mL. Conclusion The proposed method can be used to detect the content of curcumin in human urine samples and this new assay using PQAS as a probe was more sensitive and displayed a wider linear range than that reported previously. Copyright © 2011 John Wiley & Sons, Ltd.

  • determination of antibacterial quaternary ammonium compound in lozenges and human serum by resonance Light Scattering Technique
    Journal of Pharmaceutical and Biomedical Analysis, 2008
    Co-Authors: Zhanguang Chen, Yurui Peng, Junhui Chen, Li Zhu
    Abstract:

    Abstract A method for the specific determination of an antibacterial quaternary ammonium compound Dequalinium chloride (DQC) was described in this paper. At pH 0.5, the resonance Light Scattering (RLS) intensity of sodium dodecyl benzene sulfonate (SDBS) remarkably was enhanced by adding DQC. A RLS peak at 392.0 nm was found, and the enhanced intensity of RLS at this wavelength was proportional to the concentration of DQC in the range of 0.096–2.88 μg/mL. The detection limit was 2.98 ng/mL and the correlation coefficient was r  = 0.9988 ( n  = 9). The method was applied to the analysis of DQC in lozenges and human serum. The results indicated that the method was sensitive, simple, practical and useful in the clinical assay.

  • a novel histidine assay using tetraphenylporphyrin manganese iii chloride as a molecular recognition probe by resonance Light Scattering Technique
    Analytica Chimica Acta, 2006
    Co-Authors: Zhanguang Chen, Jinbin Liu, Yali Han, Li Zhu
    Abstract:

    Abstract A novel histidine-selective method has been developed for the determination of histidine in aqueous solutions by resonance Light Scattering (RLS) Technique. At pH 8.0, the weak RLS intensity of tetraphenylporphyrin manganese (III) chloride [MnTPPCl] was greatly enhanced by the addition of histidine with the maximum peak located at 483 nm. Under the optimum conditions, it was found that the enhanced RLS intensity was in proportion to the concentration of histidine in the range 7.8 × 10 −7 –2.4 × 10 −5  mol l −1 . Low detection limit of 9.2 × 10 -8  mol l −1 has been achieved. The histidine concentrations in synthetic samples and real samples were determined with satisfactory results. The sensitivity and selectivity of this method are high enough to permit the determination of trace amounts of histidine without any significant interference from high levels of other components such as common anions and especially, other amino acids.