Showing papers by "Hye Jin Lee published in 2010"

Attomolar detection of protein biomarkers using biofunctionalized gold nanorods with surface plasmon resonance

Abstract: This paper describes an ultrasensitive surface plasmon resonance (SPR) detection method using biofunctionalized gold nanorods for the direct detection of protein biomarkers. Immunoglobulin E (IgE), which has separate antibody and DNA aptamer binding sites, was chosen as a model protein for which a sandwich assay platform was designed. Detection was achieved via the specific adsorption of unlabelled IgE proteins onto the surface immobilized aptamer followed by the specific adsorption of anti-IgE coated gold nanorods (Au-NRs). Using the biofunctionalized nanorods in conjunction with SPR, we were able to directly measure IgE proteins at attomolar concentrations. This is a remarkable 108 enhancement compared to conventional SPR measurements of the same surface sandwich assay format ‘anti-IgE/IgE/surface bound IgE-aptamer’ in the absence of gold nanorod signal amplification.

Amperometric proton selective sensors utilizing ion transfer reactions across a microhole liquid/gel interface

Abstract: A new cost-effective amperometric proton selective sensor utilizing a single microhole interface between two immiscible electrolyte solutions (ITIES) is developed. The sensing methodology is based on measuring currents associated with proton transfer across the interface assisted by a proton selective ionophore. The ellipse shaped micro-interface was first fabricated by simple mechanical punching with a sharp needle on a thin PVC film (12 μm thick) commercially available as a food wrapping material. The microhole was then filled up with a gellified polyvinylchloride (PVC)-2-nitrophenyloctylether (NPOE) to create a single microhole liquid/liquid interface. Direct ion transfer reactions across the polarized interface serving as ion sensing platforms were studied using cyclic voltammetry. In order to enhance the selectivity of proton sensing, a proton selective ionophore, octadecyl isonicotinate (ETH1778), was incorporated into the organic gel layer and their electrochemical sensing characteristics were investigated using cyclic voltammetry and differential pulse stripping voltammetry. As an example, we employed the proton selective sensor for the determination of glucose concentrations. The detection scheme involves two steps: (i) protons are first generated by the oxidation of glucose with glucose oxidase in the aqueous phase; and (ii) the current associated with the proton transfer across the interface is then measured for correlating the concentration of glucose.

Degradation of malic acid in wine by immobilized Issatchenkia orientalis cells with oriental oak charcoal and alginate.

Abstract: Aims: To test degradation of malic acid content in wine by immobilized Issatchenkia orientalis KMBL 5774 cells recently isolated from Korean wine pomace as a malic acid-degrading yeast. Methods and Results: I. orientalis KMBL 5774 cells were immobilized using a mixture of oriental oak (Quercus variabilis) charcoal with sodium alginate. When the immobilized yeast cells were observed on a scanning electron microscope, cells were efficiently immobilized on the surface area of the charcoal. A Korean wine containing a high level of malic acid was treated with the immobilized yeast cells. The HPLC analysis of the malic acid content in the treated wine showed the malic acid content was reduced to 0AE75 mg ml )1 after treatment from the original content of 8AE96 mg ml )1 , representing 91AE6% of the malic acid was degraded during the treatment. Conclusions: The immobilization of the malic acid-degrading yeasts with oriental oak charcoal and sodium alginate is useful for degradation of malic acid in wines containing a high level of malic acid with no significant increase in other acids. Significance and Impact of the study: Malic acid is sometimes detrimental to the quality of wines when present at high concentrations in some varieties. The immobilized I. orientalis KMBL5774 cells appear to be a promising candidate in view of developing biotechnological methods for reduction of malic acid contents in wine.

The Effect of Coating Thickness on the Electrochemical Properties of a Li-La-Ti-O-coated Li(Ni0.3Co0.4Mn0.3)O2 Cathode

Abstract: A Li[Ni0.3Co0.4Mn0.3]O2 cathode was modified by coating with Li-La-Ti-O, and the effect of the coating thickness on their electrochemical properties was studied. The thickness of the coating on the surface of Li[Ni0.3Co0.4Mn0.3]O2 was increased by increasing the wt % of the coating material. The rate capability of the Li-La-Ti-O-coated electrode was superior to that of the pristine sample. 1- and 2-wt %-coated samples showed considerable improvement in capacity retention at high C rates. However, the rate capability of a 5-wt %-coated sample decreased. All the coated samples showed a high discharge capacity and slightly improved cyclic performance under a high cut-off voltage (4.8 V) condition. Results of a storage test confirmed that the Li-La-Ti-O coating layer was effective in suppressing the dissolution of the transition metals as it offered protection from the attack of the acidic electrolyte. In particular, the 2- and 5-wt %-coated samples showed a better protection effect than the 1-wt %-coated sample.

An Amperometric Proton Selective Sensor with an Elliptic Microhole Liquid/Gel Interface for Vitamin-C Quantification

Abstract: An amperometric ascorbic acid selective sensor utilizing the transfer reaction of proton liberated from the dissociation of ascorbic acid in aqueous solution across an elliptic micro-hole water/ organic gel interface is demonstrated. This redox inactive sensing platform offers an alternative way for the detection of ascorbic acid to avoid a fouling effect which is one of the major concerns in redox based sensing systems. The detection principle is simply measuring the current change with respect to the assisted transfer of protons by a proton selective ionophore (e.g., ETH 1778) across the micro-hole interface between the water and the polyvinylchloride-2-nitrophenyloctylether gel phase. The assisted transfer reaction of protons generated from ascorbic acid across the polarized micro-hole interface was first characterized using cyclic voltammetry. An improved sensitivity for the quantitative analysis of ascorbic acid was achieved using differential pulse stripping voltammetry with a linear response ranging from 1 to 100 µM concentrations of ascorbic acid. As a demonstration, the developed sensor was applied for analyzing the content of vitamin-C in different types of commercial pharmaceutical tablets and syrups, and a satisfactory recovery from these samples were also obtained.

Comparision of Blind Technique and Ultrasonography Guided Technique of Subacromial Subdeltoid Bursa Injection

Abstract: Objective: To evaluate the accuracy and effect of ultrasonography guided subacromial subdeltoid (SASD) bursa injection on the shoulder pain and function compared to blind technique. Method: Twenty-eight patients diagnosed as SASD bursitis were administered with SASD injection of corticosteroids randomly by either blind or US guided technique and then assessed by ultrasonography to confirm the accuracy. Shoulder pain and function were evaluated by visual analog scale with Hawkin's impingement test, active range of motion (ROM) of the shoulder, University of California-Los Angeles (UCLA) shoulder rating scale before and 1 week after the injection. Results: The accuracy of SASD injection using blind technique was 42.8%, however, US-guided injection showed 100% accuracy, significantly higher than blind technique (p

Genetic variation of umami taste genes in Koreans

Abstract: Umami is a pleasant savoury taste imparted by glutamate, a type of amino acid, and ribonucleotides, including inosinate and guanylate, which occur naturally in many foods including meat, fish, vegetables and dairy products. A heterodimer of TAS1R1 and TAS1R3 is known to function as umami taste receptor in humans. To address the association between genetic polymorphism of TAS1R1 / TAS1R3 genes and individual difference in umami taste sensitivity, we have examined the entire coding region of these genes using PCR-mediated direct sequencing analysis. A total of 11 SNPs were identified from 98 unrelated Korean individuals and were in Hardy-Weinberg Equilibrium. Four out of 11 SNPs were found in the exons and two of them were nonsynonymous ones. These coding SNPs (cSNPs), p.A372T in TAS1R1 and p.C757R in TAS1R3 genes, were common in Koreans, so these will be useful resource for further studies to find a functional allele for individual variation to umami taste sensitivity in our population.

Enhancement of CO Tolerance on Electrodeposited Pt Anode for Micro‐PEM Fuel Cells

Abstract: Electrodeposited and sprayed Pt anode catalysts were electrochemically characterised by CO stripping voltammetry as well as their activity to CO tolerance in micro-PEMFCs was demonstrated using polarisation measurements. While the onset and peak potentials of CO oxidation on the sprayed Pt/C varied with the CO coverage, these were lower (∼50 mV) with the electrodeposited Pt anode. This difference is attributed to the varying properties of the Pt–OH on either rough or smooth surface mainly created from different sizes of Pt particles. In fuel cell performance test, the electrodeposited Pt anode showed maximum power density of 360 mW cm–2 and it was markedly (∼110 mW cm–2) higher than the sprayed Pt/C anode. The enhanced activity of the electrodeposited Pt anode is also reflected by the fact that the entire amount of adsorbed CO becomes almost desorbed during the first three polarisation scans, while with the Pt/C anode at least five cycles are required.

Genetic Polymorph isms and Haplotype Analysis of Sweet Taste Receptor TAS1R2 Gene in the Korean Population

Abstract: Sweetness plays an important role in providing calories and promoting appetite for food. Since it has been known that genetic factor(s) is involved in individual differences in taste sensitivity in humans, this study aimed to examine genetic variations of the TAS1R2 gene, one of the components for tasting sweet compounds, by using DNA sequencing analysis from 98 unrelated Korean subjects. As a result, 12 different single nucleotide polymorphisms (SNPs) were identified in the hTAS1R2 gene and most of them were nonsynonymous. Also, two novel SNPs were found for the first time in this study. It was noted that the frequencies of these SNPs were common in the Korean population. 20 different haplotypes with coding SNPs (cSNPs) were also found in this study. Three out of these haplotypes were common, showing frequencies of > 10%. The repertoire and frequencies of cSNPs and haplotypes in the hTAS1R2 gene will provide information that will help identify a functional ligand receptor common in the Korean population.

Spr sensor for fuel measurement of a fuel cell having a modified metal thin film surface, and manufacturing method therefor

Abstract: The present invention relates to an SPR sensor for measuring the fuel concentration of a fuel cell, which can exactly and reproducibly measure the fuel concentration of a fuel cell and be applied to existing SPR sensors. The present invention also relates to a manufacturing method for the SPR sensor for measuring the fuel concentration of a fuel cell, which can enhance the properties of the SPR sensor without excessive increases in complicated processes and manufacturing costs.