이재승 교수

Color is everything: Hg2+ in aqueous media is detected by the formation of thymidine–Hg2+–thymidine coordination complexes, which raises the melting temperature of the DNA-hybridized gold nanoparticle probes and thus the temperature at which the probes disperse and effect a purple-to-red color change. The method has very high sensitivity and selectivity, and it provides a simple and fast colorimetric readout (see picture).

We report a new strategy for preparing silver nanoparticle-oligonucleotide conjugates that are based upon DNA with cyclic disulfide-anchoring groups. These particles are extremely stable and can withstand NaCl concentrations up to 1.0 M. When silver nanoparticles functionalized with complementary sequences are combined, they assemble to form DNA-linked nanoparticle networks. This assembly process is reversible with heating and is associated with a red shifting of the particle surface plasmon res

We report the development of a highly sensitive and selective colorimetric detection method for cysteine based upon oligonucleotide-functionalized gold nanoparticle probes that contain strategically placed thymidine-thymidine (T-T) mismatches complexed with Hg2+. This assay relies upon the distance-dependent optical properties of gold nanoparticles, the sharp melting transition of oligonucleotide-linked nanoparticle aggregates, and the very selective coordination of Hg2+ with cysteine. The conce

A synthesis strategy for the systematic control of the pore wall thickness has been developed for the mesoporous silicas with 2-D hexagonal order using ionic and nonionic surfactant mixtures. The mesoporous silicas have been used as templates for the synthesis of 2-D hexagonally ordered mesoporous carbons with controlled pore diameters. The synthesis strategy and results are useful not only for tailoring the properties of the mesoporous materials but also for extending our insights into the synt

The safe and effective delivery of RNA therapeutics remains the major barrier to their broad clinical application. Here we develop a new nanoparticulate delivery system based on inorganic particles and biodegradable polycations. First, gold nanoparticles were modified with the hydrophilic polymer poly(ethylene glycol) (PEG), and then small interfering RNA (siRNA) was conjugated to the nanoparticles via biodegradable disulfide linkages, with approximately 30 strands of siRNA per nanoparticle. The

Farbe ist alles: Hg2+ lässt sich in wässrigen Medien durch die Bildung von Thymidin-Hg2+-Thymidin-Koordinationskomplexen nachweisen, die die Schmelztemperatur der DNA-hybridisierten Goldnanopartikelsonden erhöht und damit die Temperatur, bei der die Sonden unter Farbänderung von Violett zu Rot dispergieren. Das Verfahren ist sehr empfindlich und selektiv und ermöglicht ein einfaches und schnelles kolorimetrisches Auslesen (siehe Bild).

We have developed a chip-based scanometric method for the detection of mercuric ion (Hg (2+)). This method takes advantage of the cooperative binding and catalytic properties of DNA-functionalized gold nanoparticles and the selective binding of a thymine-thymine mismatch for Hg (2+). The limit of detection of this assay in buffer and environmentally relevant samples (lake water) is 10 nM (2 ppb) Hg (2+), which is the U.S. Environmental Protection Agency (EPA) limit of [Hg (2+)] for drinkable wat

We present a novel method for size-selectively separating mixtures of nanoparticles in aqueous media utilizing the inherent chemical recognition properties of DNA and the cooperative binding properties of DNA-functionalized gold nanoparticles. We have determined that the melting temperatures (T(m)s) of aggregates formed from nanoparticles interconnected by duplex DNA are dependent upon particle size. This effect is proposed to derive from larger contact areas between the larger particles and the

We describe the facile synthesis of stable gold nanoparticle clusters densely functionalized with DNA (DNA-AuNP clusters) using dithiothreitol and monothiol DNA and their thermally reversible assembly properties. The size of the clusters exhibits a very narrow distribution and can be easily controlled by adjusting the stoichiometry of dithiothreitol and DNA, leading to a variety of colors due to the surface plasmon resonance of the AuNP clusters. Importantly, the DNA-AuNP clusters exhibit highly

We have investigated the hybridization properties of DNA-gold nanoparticle conjugates and have discovered that the hybridization properties are dramatically affected by controlling various synthetic and environmental conditions. We have further demonstrated that moderate DNA loading instead of high loading per nanoparticle significantly enhances the hybridization rates of DNA-gold nanoparticle conjugates, which allows one to precisely design their hybridization properties to distinguish a single

An accurate method of analysis is presented for optically preamplified receivers using an eigenfunction expansion technique in the optical frequency domain. Excluding three conventional simplifying assumptions on optical filters, electrical circuits, and amplified spontaneous emission, our method can give accurate predictions to the bit-error probabilities in real systems where the amplified spontaneous emission is the dominant noise.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xl