So-Jung Park

A DNA array detection method is reported in which the binding of oligonucleotides functionalized with gold nanoparticles leads to conductivity changes associated with target-probe binding events. The binding events localize gold nanoparticles in an electrode gap; silver deposition facilitated by these nanoparticles bridges the gap and leads to readily measurable conductivity changes. An unusual salt concentration-dependent hybridization behavior associated with these nanoparticle probes was expl

We report how to control the self-assembly of magnetic nanoparticles and a prototypical amphiphilic block-copolymer composed of poly(acrylic acid) and polystyrene (PAA-b-PS). Three distinct structures were obtained by controlling the solvent-nanoparticle and polymer-nanoparticle interactions: (1) polymersomes densely packed with nanoparticles (magneto-polymersomes), (2) core-shell type polymer assemblies where nanoparticles are radially arranged at the interface between the polymer core and the

DNA hybridization enables the three-dimensional assembly of Au nanoparticles and streptavidin. The high-density DNA-modified Au nanoparticles were stable to nonspecific binding of streptavidin. Structural and melting investigations on the assemblies showed their formation was reversible.

Programmed -1 ribosomal frameshifting (-1 RF) is an essential regulating mechanism of translation used by SARS-CoV (severe acute respiratory syndrome coronavirus) to synthesize the key replicative proteins encoded by two overlapping open reading frames. The integrity of RNA pseudoknot stability and structure in the -1 RF site is important for efficient -1 RF. Thus, small molecules interacting with high affinity and selectivity with the RNA pseudoknot in the -1 RF site of SARS-CoV (SARS-pseudokno

Herein, we report a high-yield click synthesis and self-assembly of conjugated amphiphilic block copolymers of polythiophene (PHT) and polyethylene glycol (PEG) and their superstructures. A series of different length PHT(m)-b-PEG(n) with well-defined relative block lengths was synthesized by a click-coupling reaction and self-assembled into uniform and stably suspended nanofibers in selective solvents. The length of nanofibers was controllable by varying the relative block lengths while keeping

The spatial arrangement of plasmonic nanoparticles can dramatically affect their interaction with electromagnetic waves, which offers an effective approach to systematically control their optical properties and manifest new phenomena. To this end, significant efforts were made to develop methodologies by which the assembly structure of metal nanoparticles can be controlled with high precision. Herein, recent advances in bottom-up chemical strategies toward the well-controlled assembly of plasmon

We report a novel class of amphiphilic conjugated block copolymers composed of poly(3-octylthiophene) and poly(ethylene oxide) (POT-b-PEO) that exhibit highly tunable photoluminescence colors spanning from blue to red. POT-b-PEO self-assembles into various well-defined core/shell-type nanostructures as a result of its amphiphilicity. The self-assembly structure can be readily controlled by altering the solvent composition or by other external stimuli. The color change was completely reversible,

We report the size-controlled self-assembly of polymersomes through the cooperative self-assembly of nanoparticles and amphiphilic polymers. Polymersomes densely packed with magnetic nanoparticles in the polymersome membrane (magneto-polymersome) were fabricated with a series of different sized iron oxide nanoparticles. The distribution of nanoparticles in a polymersome membrane was size-dependent; while small nanoparticles were dispersed in a polymer bilayer, large particles formed a well-order

If a solution of DNA-coated nanoparticles is allowed to crystallize, the thermodynamic structure can be predicted by a set of structural design rules analogous to Pauling’s rules for ionic crystallization. The details of the crystallization process, however, have proved more difficult to characterize as they depend on a complex interplay of many factors. This chapter describes that this crystallization process is dictated by the individual DNA bonds and that the effect of changing structural or

Hollow silica nanoparticles can be spontaneously generated without a template on the basis of the porous nature of silica and the high surface energy on the nanometer scale. We show that solid silica particles synthesized by the Stober and microemulsion methods initially develop small pores inside the nanoparticles under slightly basic conditions as a result of base-catalyzed etching. With further reaction, those small seed pores merge into a single void to reduce the surface energy of small por

The complex, coupled mechanisms of charge transfer and oxidative damage in organic electronic devices (such as organic light-emitting diodes (OLED), solar cells, etc.) have been elucidated by a new technique that combines single-molecule spectroscopy with charge injection from a metal electrode. The experiments employed a sandwich device architecture (Au/TPD/MEH-PPV:PMMA/SiO2/ITO), essentially a modified OLED with a charge-blocking layer (SiO2) to suppress charge injection at the ITO electrode.

We report a synthetic approach to produce raspberry-like plasmonic nanostructures with unusually strong magnetic resonances, termed raspberry-like metamolecules (raspberry-MMs). The synthesis based on the surfactant-assisted templated seed-growth method allows for the simultaneous one-step synthesis and assembly of well-insulated gold nanoparticles. The aromatic surfactant used for the syntheses forms a thin protective layer around the nanoparticles, preventing them from touching each other and

Gold nanoshells covered with sharp rods called “spiky gold nanoshells” are synthesized by employing a silver-assisted seed-growth method for heterogeneous nanoparticle syntheses at polymer/water interfaces. It is found that silver ions in the growth solution play an important role in forming uniform gold shells as well as regulating the surface morphology. The optical properties of spiky gold nanoshells are investigated by single-particle scattering measurements, single-particle surface-enhanced