Understanding fluid flows in extended nanospace (10-1000 nm) is a fundamental issue to develop novel
nanofluidic systems. The present study measured pressure driven flows in
a 410 nm fused silica channel by 100- 300 kPa. A nanoscale particle tracking
method using 64 nm fluorescent particle and the evanescent wave with total
internal reflection of laser beam was developed to obtain the flow profile.
The particle position in the nanochannel was determined from the fluorescent
intensity, which is proportional to the evanescent wave intensity decaying
exponentially from the wall. Flow velocity in the nanochannel, which is
smaller than the optical diffraction limit, was successfully obtained.
This study provides basic knowledge of fluid and mass transport in nanospace.
Because the characteristic features of metal nanoparticles arise from their unique size-dependent properties, including localized surface plasmon resonance and Coulomb charging effects, the convenient size control holds a prominent position in metal nanoparticles synthesis. Multidentate organic ligand molecules have potentials not only to passivate the inorganic nanoparticles but also to tune their structures and functions. Here, we designed a series of rigid bidentate ligands and investigated the size focusing effects depending on different distances between the two coordination sites on the gold nanoparticles. The diameter of the ligand-protected gold nanoparticles increased with increases in the distances between the two coordination sites, confirming that the size of the metal NPs could be controlled by changing the ligand structure. We discovered that the cross linking of surface atoms by the bidentate ligand plays an important roles for the size focusing. This result gives us a novel opportunity to control the size of metal NPs by designing the structure of multidentate ligands.
We carried out femtosecond transient reflectivity measurements to probe the electron-phonon coupling constant (λ) in an electron-beam-irradiated peanut-shaped C60 polymer film. By investigating the temperature-dependent carrier dynamics, we found λ ≃ 0.06, which is smaller than the value of alkali-doped C60 compounds, in which adjacent C60 molecules are weakly connected via a few carbon atoms. This implies that an increase in the number of carbon atoms connecting the adjacent C60 molecules reduces the magnitude of λ in C60-related materials.
A novel system for immobilizing enzymes onto nanoparticles has been developed. Enzymes of Tk-subtilisin attached Met-tag to C-terminus were successfully immobilized onto the surface of gold/iron-oxide composite nanoparticles. Immobilization by the Met-tag system was more effective to maintain enzyme activity than that by the carbbodiimide method.
Nanomaterials which exhibit both stability and functionality are currently considered to hold the most promise as components of nanotechnology devices. Thiolate (RS)-protected gold nanoclusters (Aun(SR)m) are attracting significant attention in this regard and, among these, the magic clusters are believed to be the best candidates since they are the most stable. We are engaged in investigating the effects of heteroatom doping and protection by functional ligands on the stability and physical/chemical properties of these clusters. Through these studies, we aims to establish methods of modifying magic Aun(SR)m clusters as a means of creating metal clusters that are both robust and functional. This paper reports our studies toward the creation of highly stable nanomaterials.
Thiolate-protected Au25 clusters were used to load monodisperse gold nanoclusters (1.2 ± 0.3 nm) onto
BaLa4Ti4O15 to create photocatalysts. The photocatalytic activity of the
resulting material for water splitting was determined to be 2.6 times higher
than that of catalysts loaded with larger gold nanoparticles (10−30 nm)
via conventional photodeposition.
Buckling instabilities in soft materials, specifically wrinkling, have led to the formation of unique surface patterns for a wide range of applications that are related to surface topography and its dynamic tuning. In this study, we present the fabrication of various wrinkle structures on a PDMS elastomer using 3D-streching method and application for SERS active surface on these structure with a metal deposition.