Won Seok Han

A Selective Fluoroionophore Based on BODIPY‐functionalized Magnetic Silica Nanoparticles: Removal of Pb2+ from Human Blood

Get the lead out: The title fluorescence receptor exhibits a high affinity and selectivity for Pb(2+) over competing metal ions in water (see picture) with an overall emission change of approximately 8-fold at the emission maximum for Pb(2+). The fluorescence receptor can remove 96 % of 100 ppb Pb(2+) from human blood, and can be useful and effective for the selective and rapid removal of Pb(2+) in vivo.

A Chromo‐Fluorogenic Tetrazole‐Based CoBr2 Coordination Polymer Gel as a Highly Sensitive and Selective Chemosensor for Volatile Gases Containing Chloride

Crystalline coordination polymers are a newer class of organic–inorganic hybrid nanomaterials created by infinitely extending metal–ligand coordination interactions. These polymers show promise in a broad range of applications, including gas storage, molecular sieves, ion exchange, sensing, magnetism, and catalysis. [1, 2] Recently, a rational-design strategy for supramolecular gels based on the concept of coordination polymers is attracting interest. [3–6] In particular, recent studies have demonstrated that simple bridging organic units can facilitate the formation of coordination polymer gels in the absence of auxiliary moieties (e.g., urea, sugar, cholesterol, long alkyl chains), offering new possibilities to produce functional soft materials from structurally

Lysine-Functionalized Silver Nanoparticles for Visual Detection and Separation of Histidine and Histidine-Tagged Proteins

A new chromogenic chemosensor based on lysine-functionalized silver nanoparticles 1 was prepared and characterized by transmission electron microscopy (TEM), Fourier transform Raman, and ultraviolet-visible (UV-vis) spectroscopy. The color changes of nanoparticles 1 in the absence and the presence of metal ion were observed upon addition of various amino acids and proteins in aqueous solution. Among the various amino acids, the sensor 1 in the absence of metal ion shows a novel colorimetric sensor with capability to probe histidine and histidine-tagged proteins. On the other hand, the color changes of 1 in the presence of metal ions such as KCl or NiCl(2) did not occur with any amino acids. Therefore, the sensor 1 in the absence of metal ion responds selectively to histidine, a response which can be attributed to its aggregation induced by histidine with high numbers of electrostatic interactions. This highly selective sensor 1 allows a rapid quantitative assay of histidine to concentrations as low as 5.0 microM, providing a new tool for the direct measurement of histidine and histidine-tagged proteins in vitro system. Furthermore, we examined the effect of pH on absorbance (A(520)) of 1 in the presence of histidine (pH 4-12). The absorbance under basic conditions was higher than that under acidic or neutral conditions, in accord with the stronger aggregation of 1 with histidine by electrostatic interaction between the carboxylate anion of 1 and ammonium protons of histidine under basic conditions.

A Highly Sensitive and Selective Turn‐On Fluorogenic and Chromogenic Sensor Based on BODIPY‐Functionalized Magnetic Nanoparticles for Detecting Lead in Living Cells

A new fluoro-chromogenic chemosensor based on BODIPY-functionalized Fe(3)O(4)@SiO(2) core/shell nanoparticles 1 has been prepared. Chemosensor 1 exhibits a high affinity and selectivity for Pb(2+) over competing metal ions tested. Moreover, confocal microscopy, and flow cytometry experiments established that 1 can be used for detecting Pb(2+) levels within living cell.

Stimuli-responsive supramolecular nanostructure from amphiphilic calix[4]arene and its three-dimensional dendritic silver nanostructure.

We synthesized a tetrameric amphiphilic molecule ( 1) based on a calix[4]arene building block that self-assembled into different tunable and stable aggregation structures at different pH values in aqueous solution. The amphiphilic calix[4]arene molecule ( 1) formed a spherical structure at pH 3. However, 1 formed a hollow necklacelike structure of 500 nm diameter at pH 7. These results indicate that the self-assembled morphologies of 1 are strongly dependent on pH values. In addition, a 3D dendritic silver nanostructure was obtained by the self-assembly of 1 at pH 7.

Thymidine-functionalized silica nanotubes for selective recognition and separation of oligoadenosines

Thymidine receptor residues were covalently attached to the inner side wall of silica nanotubes (SNTs). The adsorption capacities of the thymidine-functionalized silica nanotubes (T-SNTs) with nucleic acids and oligonucleic acids were evaluated. The T-SNTs exhibited excellent selectivity both in recognition and separation of adenosine and adenosine-based oligonucleotides, because adenosine and oligoadenosine were selectively bound to the inner surface of T-SNTs by formation of complementary intermolecular hydrogen bonds. On the other hand, guanosine, cytosine and oligoguanosine derivatives were not bound to the T-SNTs. The T-SNTs selectively separated 95% of oligoadenosine from a mixture of equal amounts of oligocytosine and oligoguanosine. Our results imply that the T-SNTs can be used as a selective receptor and separator for the extraction and separation of adenosine and oligoadenosine derivatives in aqueous solution.