Sang-Hyo Kim

A dual gold nanoparticle conjugate-based lateral flow assay (LFA) method for the analysis of troponin I.

For signal amplification without an additional operation step in a gold nanoparticle (AuNP)-based lateral flow assay (LFA), a new and simple method utilizing two AuNP-antibody conjugates was developed. The 1st conjugate was the AuNP immobilized with an anti-troponin I antibody and blocked with bovine serum albumin (BSA), and the 2nd conjugate was the AuNP immobilized with an anti-BSA antibody and blocked with human serum albumin. The two conjugates were encapsulated in different pads, respectively. A scheme of the LFA system is described in the part A of first figure. The size of the two conjugates was very critical in the detection sensitivity of troponin I. When 10nm for the 1st and 40 nm for the 2nd were used, the detection sensitivity increased about a 100-fold compared to the conventional LFA. We could detect as low as 0.01 ng/mL troponin I in 10 min using the dual AuNP conjugate-based LFA, which was successfully applied in the analysis of serum samples of patients with myocardial infarction.

New families of binary sequences with low correlation

For a positive integer, n, new families, S and U, of binary sequences of period 2/sup n/-1 with low correlations are proposed, where for some positive integer, e, S is defined for odd n/e and U for even n/e. The family S has four-valued correlations and is a generalization of the family of Gold-like sequences introduced by S. Boztas and P.V. Kumar (see ibid., vol.40, p.532-7, 1994). The family U, which is also a generalization of the sequence family defined by P. Udaya (Polyphase and frequency hopping sequences obtained from finite rings, Ph.D. dissertation, Dept. Elec. Eng., Indian Inst. Technol., Kanpur, 1992), has six-valued correlations. The relationship between Gold-like sequences and Gold sequences is the same as the relationship between the family S and the family constructed from the binary sequences partially contributed by R. Gold (see ibid., vol.IT-14, p.154-6, 1968), T. Kasami (see Coordinated Sci. Lab., Univ. of Illinois,Urbana-Champaign, Tech. Rep. R-285, AD 632574, 1966), and Welch. Using a lifting idea (No, J.-S. and Kumar, P.V., ibid., vol.35, p.371-9, 1989) for the families S and U, families of binary sequences with the same correlation distributions and large linear span are also constructed.

AC frequency characteristics of coplanar impedance sensors as design parameters

Glass-based microchannel chips were fabricated using photolithographic technology, and Pt thin-film microelectrodes, as coplanar impedance sensors, were integrated on them. Longitudinal design parameters, such as interelectrode spacing and electrode width, of coplanar impedance sensors were changed to determine AC frequency characteristics as design parameters. Through developing total impedance equations and modeling equivalent circuits, the dominant components in each frequency region were illustrated for coplanar impedance sensors and the measured results were compared with fitted values. As the ionic concentration increased, the value of the frequency-independent region decreased and cut-off frequencies increased. As the interelectrode spacing increased, cut-off frequencies decreased and total impedance increased. However, the width of each frequency-independent region was similar. As the electrode area increased, f(low) decreased but f(high) was fixed. We think that the decrease in R(Sol) dominated over the influence of other components, which resulted in heightening f(low) and f(high). The interelectrode spacing is a more significant parameter than the electrode area in the frequency characteristics of coplanar sensors. The deviation of experimentally obtained results from theoretically predicted values may result from the fringing effect of coplanar electrode structure and parasitic capacitance due to dielectric substrates. We suggest the guidelines of dominant components for sensing as design parameters.

New constructions of quaternary low correlation zone sequences

In this paper, given a composite integer n, we propose a method of constructing quaternary low correlation zone (LCZ) sequences of period 2/sup n/-1 from binary sequences of the same length with ideal autocorrelation. These new sequences are optimal with respect to the bound by Tang, Fan, and Matsufuji. The correlation distributions of these new quaternary LCZ sequences constructed from m-sequences and Gordon-Mills-Welch (GMW) sequences are derived.

High sensitivity detection of 16s rRNA using peptide nucleic acid probes and a surface plasmon resonance biosensor

A signal enhancing method allowing highly sensitive detection of E. coli 16s rRNA was developed using peptide nucleic acid (PNA) as a capture probe and a surface plasmon resonance (SPR) sensor as a detector. 16s rRNA has been used as a genetic marker for identification of organisms, and can be analyzed directly without PCR amplification due to the relatively high number of copies. PNA has a neutral backbone structure, therefore hybridization with 16s rRNA results in the ionic condition being changed from neutral to negative. A cationic Au nanoparticle was synthesized and used for signal amplification by ionic interaction with 16s rRNA hybridized on the PNA probe-immobilized SPR sensor chip. This method resulted in a detection limit of E. coli rRNA of 58.2+/-1.37 pg mL(-1). Using this analytical method, Staphylococcus aureus was detected without purification of rRNA.

Linear complexity over F/sub p/ and trace representation of Lempel-Cohn-Eastman sequences

In this article, the linear complexity over F/sub p/ of Lempel-Cohn-Eastman (1977) sequences of period p/sup m/-1 for an odd prime p is determined. For p=3,5, and 7, the exact closed-form expressions for the linear complexity over F/sub p/ of LCE sequences of period p/sup m/-1 are derived. Further, the trace representations for LCE sequences of period p/sup m/-1 for p=3 and 5 are found by computing the values of all Fourier coefficients in F/sub p/ for the sequences.

New cyclic relative difference sets constructed from d-homogeneous functions with difference-balanced property

For a prime power q, we show that a cyclic relative difference set with parameters (q/sup n/-1/q-1,q-1,q/sup n-1/,q/sup n-2/) can be constructed from a d-homogeneous function from F/sub q//sup n//spl bsol/{0} onto F/sub q/ with difference-balanced property, where F/sub q//sup n/ is the finite field with q/sup n/ elements. This construction method enables us to construct several new cyclic relative difference sets with parameters (p/sup n/-1/p/sup l/-1,p/sup l/-1,p/sup n-l/,p/sup n-2l/) from p-ary sequences of period p/sup n/-1 with ideal autocorrelation property introduced by Helleseth and Gong. Using a lifting idea, other new cyclic relative difference sets can be constructed from the Helleseth-Gong (HG) sequences. Also, the 3-ranks and the trace representation of the characteristic sequences of cyclic relative difference sets from a specific class of ternary HG sequences and ternary Lin sequences are derived.

A Dielectric Biosensor Using the Capacitance Change with AC Frequency Integrated on Glass Substrates

Glass-based microchannel chips were fabricated using photolithographic technology, and Pt thin-film microelectrodes as dielectric biosensors were integrated on them. From capacitance-frequency measurements at various interelectrode distances and ionic concentrations, a significant difference between deionized (DI) water and tris-ethylenediaminetetraacetic acid (EDTA) (TE) buffer was observed in the low-frequency region. Although the capacitance (CM) of the DI water decreased as the interelectrode distance increased, that of the TE buffer was similar up to a frequency of 100 Hz, after which it was spilt in the same manner as the DI water above 100 Hz. As the ionic concentration increased, the CM of the TE buffer increased and the slope in the low frequency region changed from -0.875 to -0.425. The point where the slope changed shifted towards the frequency increase. These observations were clarified from the viewpoint of interfacial phenomena, such as the electrical double layer and Faradaic reactions, the dielectric constant related to conductivity, and the capacitance inversely proportional to the interelectrode distance. The addition of deoxyribonucleic acid (DNA) molecules (10 ng/µl) increased the capacitance and dielectric loss in the TE buffer at low frequency. It is feasible to use dielectric properties for the rapid and direct detection of biomolecules, particularly DNA molecules, without using labels or indicators.

Polymer Nanoparticles for Smart Drug Delivery

In the recent decades, polymers are widely used as biomaterials due to their favorable properties such as good biocompatibility, easy design and preparation, a variety of structures and interesting bio-mimetic character. Especially in the field of smart drug delivery, polymer played a significant role because it can deliver therapeutic agents directly into the intended site of action, with superior efficacy. The ideal requirements for designing nano-particulate delivery system are to effectively be controlled particle size, surface character; enhance permeation, flexibility, solubility and release of therapeutically active agents in order to attain the target and specific activity at a predetermined rate and time. The smart drug delivery systems have been successfully made by the advances in polymer science in the bio-nano‐ technology field. Recently, these advances have been found in various medical applications for nano-scale structures in smart drug delivery. The smart drug delivery systems should possess some important feature such as pre-scheduled rate, self controlled, targeted, predetermined time and monitor the delivery. The smart drug delivery system enhances the polymer nanoparticle better stage to their therapy regimen. They are drug carriers of natural, semi-synthetic, and synthetic polymeric nature at the nano-scale to micro-scale range. The polymeric particles are collectively named as spheres and capsules. The most of the polymeric nanoparticles with surfactants offer stability of various forms of active drugs and have useful to smart release properties. There are numerous biological applications have been reported for the nano-scale to micro-scale sized particles, such as site-targeted, controlled, and enhanced bioavailability of hydrophobic drugs [1-4]. Due to the nanoparticles size the drugs have been targeting into various applications, such as, various cancers targeting has been shown to be promising [5]. Moreover, polymeric particles proved their effectiveness in stabilizing and protecting the drug molecules such as proteins, peptides, or DNA molecules from various environmental hazards degradation [2-4, 6, 7]. So these polymers are affording the potential for various protein and gene delivery. Numerous methods had been available to fabricate

Amphiphilic triblock copolymer and a microfluidic device for porous microfiber fabrication

This paper shows successful fabrication of different diameter porous microfibers using a novel, simple and cost effective polydimethylsiloxane (PDMS)-based microfluidic device in which an amphiphilic ABA triblock copolymer, poly(p-dioxanone-co-caprolactone)-block-poly(ethylene oxide)-block-poly(p-dioxanone-co-caprolactone) (PPDO-co-PCL-b-PEG-b- PPDO-co-PCL) in dichloromethane (CH2Cl2), and de-ionized water (DI H2O) were taken in two inlets to extrude porous fibers through the outlet utilizing a dual mechanism of immersion precipitation and solvent evaporation. The flow rates of the two inlet solutions (core and sheath) were controlled such that 5–50 μl min−1 and 100 ml h−1 were used, respectively, to produce 2–200 μm diameter porous microfibers. Controlled fibronectin (an adhesive protein) release from the scaffold was observed until 8 weeks in an in vitro protein release study, which could be due to the slower scaffold PCL block degradation rate until 8 weeks of the in vitro degradation analysis. Cytocompatibility of our porous scaffold was demonstrated for its applicability as a cell culture scaffold or implant material by means of analysis of surface hydrophilicity (water and cell suspension contact angles) and mitochondrial activity (WST-1 proliferation test) using L929 mouse fibroblasts cell line. In summary, the experimental results suggest that combined use of the microfluidic device and amphiphilic triblock copolymer produces varied diameter porous fiber scaffolds which can be potentially used as a controlled protein/drug release carrier for tissue regeneration and/or drug delivery applications.