Joon-Hyung Jin

Conductivity in the I2-doped PBMPV conducting polymers

Abstract A series of I 2 -doped poly[2-buthoxy-5-methoxy-1,4-phenylenevinylene] (PBMPV) conducting polymers were synthesized and systematically studied by means of electrical conductivity measurements. The conductivity vs degree of doping as well as in situ and aging measurements reveal a peculiar behavior attributable to the dopant kinetics.

Label-free Electrochemical Detection of the Human Adenovirus 40/41 Fiber Gene

A nanoporous silicon-based label-free DNA biosensor was fabricated to monitor rapidly enteric adenovirus types 40 and 41, a leading cause of viral gastroenteritis in children. Nanoporous silicon (NPS) was formed by an anodic etching process in a mixture solution containing hydrofluoric acid and ethanol. The polypyrrole (PPy) film was directly electropolymerized on The NPS substrate. Twenty-five base pairs of probe DNA (pDNA), derived from the fiber gene, was electrochemically doped on the PPy-coated NPS substrate. The conductivity change due to the immobilized pDNA and hybridized target DNA (tDNA) was expressed as an arbitrary factor, γ, which is a normalized numerical term used for the selective quantification of the tDNA. γ was inversely proportional to the concentration of complementary tDNA, but independent of the non-complementary tDNA. The sensitivity slope for detecting tDNAc was -1.54 μM(-1), based on the factor γ in the range of 0.4 to 1.0 μM of tDNA. The surface roughness was characterized using atomic force microscopy.

Photovoltaic performance of multi-wall carbon nanotube/PEDOT:PSS composite on the counter electrode of a dye-sensitized solar cell

A composite of poly(3,4-ethylendioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) and multi-walled carbon nanotubes (MWCNTs) was cyclovoltametrically electropolymerized on a fluorine-doped tin oxide (FTO) substrate and used as a counter electrode for a dye-sensitized solar cell. The PEDOT:PSS–MWCNT composite film was investigated using scanning electron microscopy (SEM), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The CV diagrams showed that the PEDOT:PSS–MWCNT composite film has better electro-catalytic activity for the I−/I3− redox reaction than the conventional platinized FTO. The best energy conversion efficiency was observed in EIS data with an MWCNT content of 0.002 wt %.

Electrochemical properties of a fully integrated, singlewalled carbon nanotube coplanar three-electrode system on glass substrate.

Fully integrated carbon nanotube-based three-electrode electrochemical systems were photolithographically prepared on glass substrates and electrochemically characterized. O(2) plasma treatment of the transferred single-walled carbon nanotube (SWCNT) film was voltammetrically optimized in terms of applied plasma power and the elapsed time. The patterned thin film Ag layer was chemically oxidized in an acidic solution for various dip times to form a chlorinated Ag layer. The Nernstian behavior of as-prepared and seven-day-aged Ag/AgCl thin-film electrodes was investigated for optimization, and the electrodes electrochemical attributes were compared to a commercial reference electrode. A quality control evaluation and a performance assessment of the fully integrated SWCNT-transferred sensing systems were performed using cyclic voltammetry. The proposed SWCNT-based three-electrode device exhibited clear electrochemistry under voltammetric conditions, and is therefore a candidate for use in all electrochemical biosensors.

Biointerfacial Property of Plasma-Treated Single-Walled Carbon Nanotube Film Electrodes for Electrochemical Biosensors

The single-walled carbon nanotube (SWCNT)-based thin film was spray-coated on the Pt support and functionalized using O2 plasma. The effects of plasma treatment on the biointerfacial properties of the SWCNT films were analyzed by cyclic voltammogram (CV), electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV). The plasma-functionalized (pf) SWCNT electrodes modified with Legionella pneumophila-specific probe DNA strands showed a much higher peak current and a smaller peak separation in differential pulse voltammetry and a lower charge transfer resistance, compared to the untreated samples. These results suggest that the pf-SWCNT films have a better electrocatalytic character and an electron transfer capability faster than the untreated SWCNTs, due to the fact that the oxygen-containing functional groups promote direct electron transfer in the biointerfacial region of the electrocatalytic activity of redox-active biomolecules.

Electroactivity of chemical and plasma modified single-walled carbon nanotubes to application of glucose detection

Acid treatment to the carbon nanotubes (CNTs) is widely used to produce chemical functional group-substituted CNTs. However, more effective substitution of chemical functional groups is available with the O2 plasma treatment because the O2 plasma targets not only the end position but also the side-wall region of the CNTs. Amperometric results from glucose oxidase (GOD)-modified CNT electrodes confirmed that at least two times of larger effective working electrode area was observed with the O2 plasma treatment as compared to the acid treatment.