Our Work
Template synthesis of hollow silver hexapods using hexapod-shaped silver oxide mesoparticles
We use morphology-controlled silver oxide (Ag2O) mesoparticles as a sacrificial template to make well-defined Ag mesoparticles. The hexapod-shaped Ag2O mesoparticles are synthesized by retarding its reaction rate using bis (p-sulfonatophenyl) phenylphosphine dehydrate dipotassium as a ligand, and reduced into Ag hexapods by sodium borohydride. Complete conversion of Ag2O into Ag is confirmed by a series of characterization procedure, and the shape and size of Ag2O hexapods are retained during the reduction process. Reduced Ag hexapods have hollow inner structure, and interestingly show single crystalline phase, which is contrary to the previous report. A new mechanism is introduced to explain formation of hollow structure and its single crystalline phase.
We use morphology-controlled silver oxide (Ag2O) mesoparticles as a sacrificial template to make well-defined Ag mesoparticles. The hexapod-shaped Ag2O mesoparticles are synthesized by retarding its reaction rate using bis (p-sulfonatophenyl) phenylphosphine dehydrate dipotassium as a ligand, and reduced into Ag hexapods by sodium borohydride. Complete conversion of Ag2O into Ag is confirmed by a series of characterization procedure, and the shape and size of Ag2O hexapods are retained during the reduction process. Reduced Ag hexapods have hollow inner structure, and interestingly show single crystalline phase, which is contrary to the previous report. A new mechanism is introduced to explain formation of hollow structure and its single crystalline phase.
Investigation of Gold and Silver Nanoparticles as Acid–base pH Indicators and Their Transition pH Ranges
A shift of surface plasmon resonance for such aggregated gold nanoparticles can be applied to pH indicators, allowing for the substitution of traditional organic-based pH indicators. The most important characteristic of pH indicators is the transition pH range. Herein, gold and silver nanoparticles are prepared using different reducing agents, and their transition pH ranges are examined. The results showed that all nanoparticles prepared in this study exhibit similar transition pH ranges spanning 11.9–13.0, regardless of the nanoparticle material, reducing agents, and concentration.
A shift of surface plasmon resonance for such aggregated gold nanoparticles can be applied to pH indicators, allowing for the substitution of traditional organic-based pH indicators. The most important characteristic of pH indicators is the transition pH range. Herein, gold and silver nanoparticles are prepared using different reducing agents, and their transition pH ranges are examined. The results showed that all nanoparticles prepared in this study exhibit similar transition pH ranges spanning 11.9–13.0, regardless of the nanoparticle material, reducing agents, and concentration.
Formation of rod-shaped domains in Langmuir–Blodgett films composed of 7,8-dimethyl-10-dodecyl isoalloxazine
The present study shows that rod-shaped domains are formed in LB films composed of DDIwhen the DDImonolayer is compressed beyond a specific limiting area. The formation mechanismfor rod-shaped domains can be surmised from the surface pressure–mean molecular area isotherm curve and atomic force microscopy data. The fluorescence lifetimes of the rod-shaped domains or nondomainsweremeasured. The data is discussed in terms of the suggested formation mechanism of rod-shaped domains.
The present study shows that rod-shaped domains are formed in LB films composed of DDIwhen the DDImonolayer is compressed beyond a specific limiting area. The formation mechanismfor rod-shaped domains can be surmised from the surface pressure–mean molecular area isotherm curve and atomic force microscopy data. The fluorescence lifetimes of the rod-shaped domains or nondomainsweremeasured. The data is discussed in terms of the suggested formation mechanism of rod-shaped domains.
Alignment Strategies for the Assembly of Nanowires
with Submicron Diameters
We report two complementary methods that are simple and effective for the alignment of both individual and multiple nanowires over large areas. In both schemes, Au nanowires (360nm diameter, 5mm long) are assembled and aligned by employing either capillary or mechanical forces. In these studies, capillary-force-based approaches have proven useful for the alignment of groups of wires over large areas, while mechanical force approaches are better suited for the
individual placement of nanowires.
with Submicron Diameters
We report two complementary methods that are simple and effective for the alignment of both individual and multiple nanowires over large areas. In both schemes, Au nanowires (360nm diameter, 5mm long) are assembled and aligned by employing either capillary or mechanical forces. In these studies, capillary-force-based approaches have proven useful for the alignment of groups of wires over large areas, while mechanical force approaches are better suited for the
individual placement of nanowires.
Actuation of Self-Assembled
Two-Component Rodlike Nanostructures
A model for predicting the effects of stimuli-induced contraction of the polypyrrole ends of two-segment gold-polypyrrole nanorods on their assembly into curved superstructures is presented. The model and experimental data presented here show that small changes (ca. 3%) in the diameter of the polypyrrole segment of each rod will induce dramatic changes (up to 20%) in the radii of the resulting superstructures, providing a convenient means for actuating their opening and closing. We show experimentally that this actuation can be affected via humidity, temperature, and light.
Two-Component Rodlike Nanostructures
A model for predicting the effects of stimuli-induced contraction of the polypyrrole ends of two-segment gold-polypyrrole nanorods on their assembly into curved superstructures is presented. The model and experimental data presented here show that small changes (ca. 3%) in the diameter of the polypyrrole segment of each rod will induce dramatic changes (up to 20%) in the radii of the resulting superstructures, providing a convenient means for actuating their opening and closing. We show experimentally that this actuation can be affected via humidity, temperature, and light.