Biomedical subjects

Yoon-Bo Shim

Publications and source records attributed to Yoon-Bo Shim.

22 records · Page 2Linked to original sources

PubMed2004

Development of an immunosensor for the detection of vitellogenin using impedance spectroscopy.

A simple and direct immunosensor for the determination of carp (Carassius auratus) vitellogenin (Vtg), a female-specific protein, has been proposed based on an antibody-captured conducting polymer-coated electrode. The monoclonal antibody specific to carp (C. auratus) Vtg was immobilized by covalent coupling to the carboxylic acid group on the polymer. The antibody immobilization and antibody-antigen interaction have been demonstrated by means of quartz crystal microbalance and impedance spectroscopic techniques. The impedance change occurred at the sensor surface due to the specific immuno-interaction was utilized to determine Vtg. The sensor showed high selectivity and sensitive response to Vtg in a buffered medium without redox probe. Vtg was determined in the linear range from 1.0 to 8.0 microg/l with the standard deviation of +/-0.13 (n =3) and the detection limit was determined to be 0.42 microg/l. This method was applied to the determination of Vtg in real male and female carp (C. auratus) serum samples.

Antibodies↗

PubMed2003

Direct electrochemistry of horseradish peroxidase bonded on a conducting polymer modified glassy carbon electrode.

Direct electron transfer process of immobilized horseradish peroxidase (HRP) on a conducting polymer film, and its application as a biosensor for H2O2, were investigated by using electrochemical methods. The HRP was immobilized by covalent bonding between amino group of the HRP and carboxylic acid group of 5,2':5',2"-terthiophene-3'-carboxylic acid polymer (TCAP) which is present on a glassy carbon (GC). A pair of redox peaks attributed to the direct redox process of HRP immobilized on the biosensor electrode were observed at the HRPmid R:TCAPmid R:GC electrode in a 10 mM phosphate buffer solution (pH 7.4). The surface coverage of the HRP immobilized on TCAPmid R:GC was about 1.2 x 10(-12) mol cm(-2) and the electron transfer rate (ks) was determined to be 1.03 s(-1). The HRPmid R:TCAPmid R:GC electrode acted as a sensor and displayed an excellent specific electrocatalytic response to the reduction of H2O2 without the aid of an electron transfer mediator. The calibration range of H2O2 was determined from 0.3-1.5 mM with a good linear relation.

Biosensing Techniques↗

PubMed2003

Characterization of an EDTA bonded conducting polymer modified electrode: its application for the simultaneous determination of heavy metal ions.

An EDTA bonded conducting polymer modified electrode (EDTA-CPME) was fabricated by polymerization of 3',4'-diamino-2,2';5',2''-terthiophene monomer on a GCE, followed by the reaction with EDTA in the presence of catalyst. The surface of the resulting modified electrode was characterized with EQCM, ESCA, SEM, Auger electron spectroscopy, scanning Auger microscopy, and electrochemical methods. The amounts of polymer and EDTA attached on the polymer film were determined. Simple immersing of the EDTA-CPME into a sample solution led to the chemical deposition through the complexation with Pb2+, Cu2+, and Hg2+ ions, simultaniously. Various experimental parameters that affect the simultaneous analysis of the metal ions, e.g., EDTA amount, pH, deposition time, and deposition temperature, were optimized. Calibration plots for the EDTA-CPME with square wave voltammetry were obtained in the concentration range between 5.0 x 10(-10) and 1.0 x 10(-7) M for Cu(II) and between 7.5 x 10(-10) and 1.0 x 10(-7) M for Pb(II) and Hg(II). The detection limits for Pb(II), Cu(II), and Hg(II) ions were determined to be about 6.0 x 10(-10), 2.0 x 10(-10), and 5.0 x 10(-10) M, respectively. Interference effects from other metal ions were studied at various pHs and it was found that there was little or no effect on the simultaneous determination. The stability of the EDTA-CPME was remarkably improved by coating the surface with the Nafion film, and the electrode can be used for more than one month. Analytical availability of the EDTA-CPME was demonstrated by the application for the certified standard urine reference material and tap water.

Journal Article↗

PubMed2003

Disposable amperometric immunosensor system for rabbit IgG using a conducting polymer modified screen-printed electrode.

A disposable and mediatorless immunosensor based on a conducting polymer (5,2':5'2"-terthiophene-3'-carboxylic acid) coated screen-printed carbon electrode has been developed using a separation-free homogeneous technique for the detection of rabbit IgG as a model analyte. Horseradish peroxidase (HRP) and streptavidin were covalently bonded with the polymer on the electrode and biotinylated antibody was immobilized on the electrode surface using avidin-biotin coupling. This sensor was based on the competitive assay between free and labeled antigen for the available binding sites of antibody. Glucose oxidase was used as a label and in the presence of glucose, H(2)O(2) formed by the analyte-enzyme conjugate was reduced by the enzyme channeling via HRP bonded on the electrode. The catalytic current was monitored amperometrically at -0.35 V vs. Ag/AgCl and this method showed a linear range of RIgG concentrations from 0.5 to 2 microg/ml with standard deviation +/-0.0145 (n=4). Detection limit was determined to be 0.33 microg/ml.

Animals↗