Missing Piece in Colloidal Stability─Morphological Factor of Hydrophobic Nanoparticles.

Hydrophobic nanoparticles (NPs) in water were considered unstable because they lack the repulsive electrostatic interaction and steric effect to prevent aggregation. In this study, porous hydrophobic NPs of two star-shaped giant molecules, , were found to be stable in water and able to retain their kinetic stability in a wide range of temperatures, pH values, and ionic strengths. Unlike the solid hydrophobic NPs that aggregate even with the negative zeta potential (ζ) induced by surface-structured hydrogen-bonded (SHB) water, the porous morphology of NPs reduces the entropically driven hydrophobic effect to prevent aggregation.

Water-Induced Self-Assembly of Amphiphilic Discotic Molecules for Adaptive Artificial Water Channels.

Inspired by the induced-fit mechanism in nature, we developed the process of water-induced self-assembly (WISA) to make water an active substrate that regulates the self-assembly and function of amphiphilic discotic molecules (ADMs). The ADM is an isotropic liquid that self-assembles only when in contact with water. Characterization results indicate that water fits into the hydrophilic core of the ADMs and induces the formation of a hexagonal columnar phase (Col), where each column contains a hydrated artificial water channel (AWC).

Vibrational couplings and energy transfer pathways of water's bending mode.

Coupling between vibrational modes is essential for energy transfer and dissipation in condensed matter. For water, different O-H stretch modes are known to be very strongly coupled both within and between water molecules, leading to ultrafast dissipation and delocalization of vibrational energy. In contrast, the information on the vibrational coupling of the H-O-H bending mode of water is lacking, even though the bending mode is an essential intermediate for the energy relaxation pathway from the stretch mode to the heat bath.

Vesicular Membrane with Structured Interstitial Water.

Self-assembled vesicles with structured (tetrahedral order with strong hydrogen bonds) interstitial water are reported. The vesicles, known as MCsome, are assembled from metal carbonyl compounds, FpR (Fp = (Cp)Fe(PPh)(CO)(CO-), Cp = cyclopentadiene, R = CBithiophene, CPyrene or C) with the Fp heads exposed to water. The R groups are surrounded by the interstitial water with the hydrogen bonding strength variable depending on the hydrophobicity of R groups.

Organelle specific simultaneous Raman/green fluorescence protein microspectroscopy for living cell physicochemical studies.

We demonstrate a novel bio-spectroscopic technique, "simultaneous Raman/GFP microspectroscopy". It enables organelle specific Raman microspectroscopy of living cells. Fission yeast, Schizosaccharomyces pombe, whose mitochondria are green fluorescence protein (GFP) labeled, is used as a test model system.

Phonon confinement and size effect in Raman spectra of ZnO nanoparticles.

We study Raman spectra of ZnO nanoparticles of 5-12 nm size in the whole range of the first-order phonon bands. We apply the 3D phonon confinement model (PCM) for the interpretation of the observed Raman spectra. It is found that PCM is well applicable to the acoustic modes as well as to the optical ones, despite the fact that PCM has been thought not to be suitable for acoustic phonons.

A General Approach for Estimating Lamella-Thickness Distribution in Polymers with Low-Frequency Raman Spectroscopy: Application to Lamella Formation in Crystallizing Polyethylene.

A general method for estimating lamella-thickness distribution in semicrystalline polymers has been developed and applied to polyethylene (PE). The longitudinal acoustic mode (LAM) of PE appears at very low frequencies (i.e.

Polarizability tensor invariants of H, HD, and D.

We report an exhaustive compilation of wavelength-dependent matrix elements over the mean polarizability (α¯) and polarizability anisotropy (γ) operators for the rovibrational states of the H, HD, and D molecules together with an accompanying computer program for their evaluation. The matrix elements can be readily evaluated using the provided codes for rovibrational states with J = 0-15 and v = 0-4 and for any laser wavelengths in the interval 182.25-1320.

Studying anti-oxidative properties of inclusion complexes of α-lipoic acid with γ-cyclodextrin in single living fission yeast by confocal Raman microspectroscopy.

α-lipoic acid (ALA) is an essential cofactor for many enzyme complexes in aerobic metabolism, especially in mitochondria of eukaryotic cells where respiration takes place. It also has excellent anti-oxidative properties. The acid has two stereo-isomers, R- and S- lipoic acid (R-LA and S-LA), but only the R-LA has biological significance and is exclusively produced in our body.

Cylindrical micelles of a POSS amphiphilic dendrimer as nano-reactors for polymerization.

A low generation amphiphilic dendrimer, POSS-AD, which has a POSS core and eight amphiphilic arms, was synthesized and used as a nano-reactor to produce well-defined polymer nano-cylinders. Confirmed by small-angle X-ray scattering (SAXS), Raman and NMR spectrometry, monodispersed cylindrical micelles that contain a hydrophilic cavity with a diameter of 2.09 nm and a length of 4.

Analysis of root surface properties by fluorescence/Raman intensity ratio.

The aim of this study is to evaluate the existence of residual calculus on root surfaces by determining the fluorescence/Raman intensity ratio. Thirty-two extracted human teeth, partially covered with calculus on the root surface, were evaluated by using a portable Raman spectrophotometer, and a 785-nm, 100-mW laser was applied for fluorescence/Raman excitation. The collected spectra were normalized to the hydroxyapatite Raman band intensity at 960 cm.

Imaging phospholipid conformational disorder and packing in giant multilamellar liposome by confocal Raman microspectroscopy.

Liposomes are closed phospholipid bilayer systems that have profound applications in fundamental cell biology, pharmaceutics and medicine. Depending on the composition (pure or mixture of phospholipids, presence of cholesterol) and preparation protocol, intra- and inter-chain molecular interactions vary leading to changes in the quality (order and packing) of liposomes. So far it is not possible to image conformational disorders and packing densities within a liposome in a straightforward manner.

Tilted Two-Dimensional Array Multifocus Confocal Raman Microspectroscopy.

A simple and efficient two-dimensional multifocus confocal Raman microspectroscopy featuring the tilted-array technique is demonstrated. Raman scattering from a 4 × 4 square foci array passing through a 4 × 4 confocal pinhole array is tilted with a periscope. The tilted array of Raman scattering signals is dispersed by an imaging spectrograph onto a CCD detector, giving 16 independent Raman spectra formed as 16 bands with different heights on the sensor.

On-site Direct Detection of Astaxanthin from Salmon Fillet Using Raman Spectroscopy.

A new technology employing Raman spectroscopy is attracting attention as a powerful biochemical technique for the detection of beneficial and functional food nutrients, such as carotenoids and unsaturated fatty acids. This technique allows for the dynamic characterization of food nutrient substances for the rapid determination of food quality. In this study, we attempt to detect and measure astaxanthin from salmon fillets using this technology.

Estimating Percent Crystallinity of Polyethylene as a Function of Temperature by Raman Spectroscopy Multivariate Curve Resolution by Alternating Least Squares.

We have recently demonstrated a methodology to estimate the percent crystallinity (PC) of polymers directly with Raman spectroscopy and multivariate curve resolution (MCR) by alternating least-squares (ALS). In the MCR-ALS methodology, the Raman spectrum of a semicrystalline polymer is separated into two constituent components (crystalline and molten/amorphous) and their corresponding concentrations. The methodology necessitates that the Raman spectrum at any temperature be a linear combination of two MCR spectral components (one molten and one crystalline).

Microscopic solvation environments in a prototype room-temperature ionic liquid as elucidated by resonance Raman spectroscopy of iodine and bromine.

Microscopic solvation environments in a prototype ionic liquid, bmimTfN; 1-butyl-3-methyl-imidazolium-bis(trifluoromethanesulfonyl)imide, have been studied with the use of halides, X and X (X=I, Br; n=3,5), as molecular probes. Resonance Raman spectroscopy has been used to detect these halogen species existing in bmimTfN as well as in reference solvents including heptane, cyclohexane, KX/HO and benzene. In heptane and cyclohexane, only free X species are detected.

Label-free Chemical Imaging of Fungal Spore Walls by Raman Microscopy and Multivariate Curve Resolution Analysis.

Fungal cell walls are medically important since they represent a drug target site for antifungal medication. So far there is no method to directly visualize structurally similar cell wall components such as α-glucan, β-glucan and mannan with high specificity, especially in a label-free manner. In this study, we have developed a Raman spectroscopy based molecular imaging method and combined multivariate curve resolution analysis to enable detection and visualization of multiple polysaccharide components simultaneously at the single cell level.

Determination of Percent Crystallinity of Side-Chain Crystallized Alkylated-Dextran Derivatives with Raman Spectroscopy and Multivariate Curve Resolution.

We demonstrate a methodology to estimate the percent crystallinity of polymers directly with Raman spectroscopy and multivariate curve resolution (MCR) by alternating least-squares (ALS). In this methodology, the Raman spectrum of semicrystalline polymer is separated into two constituent components (crystalline and molten) and their corresponding concentrations. The percent crystallinity can be estimated as the change in area intensity of the molten spectral-component when polymer cools from a temperature above melting point to room temperature.

Automatic and objective oral cancer diagnosis by Raman spectroscopic detection of keratin with multivariate curve resolution analysis.

We have developed an automatic and objective method for detecting human oral squamous cell carcinoma (OSCC) tissues with Raman microspectroscopy. We measure 196 independent Raman spectra from 196 different points of one oral tissue sample and globally analyze these spectra using a Multivariate Curve Resolution (MCR) analysis. Discrimination of OSCC tissues is automatically and objectively made by spectral matching comparison of the MCR decomposed Raman spectra and the standard Raman spectrum of keratin, a well-established molecular marker of OSCC.

Simultaneous imaging of fat crystallinity and crystal polymorphic types by Raman microspectroscopy.

The crystalline states of fats, i.e., the crystallinity and crystal polymorphic types, strongly influence their physical properties in fat-based foods.

Pathogenesis of acute hepatopancreatic necrosis disease (AHPND) in shrimp.

Acute hepatopancreatic necrosis disease (AHPND), also called early mortality syndrome (EMS), is a recently emergent shrimp bacterial disease that has resulted in substantial economic losses since 2009. AHPND is known to be caused by strains of Vibrio parahaemolyticus that contain a unique virulence plasmid, but the pathology of the disease is still unclear. In this study, we show that AHPND-causing strains of V.

Communication: three-dimensional model for phonon confinement in small particles: quantitative bandshape analysis of size-dependent Raman spectra of nanodiamonds.

Raman spectroscopy of nano-scale materials is facing a challenge of developing a physically sound quantitative approach for the phonon confinement effect, which profoundly affects the phonon Raman band shapes of small particles. We have developed a new approach based on 3-dimensional phonon dispersion functions. It analyzes the Raman band shapes quantitatively in terms of the particle size distributions.

Imaging molecular crystal polymorphs and their polycrystalline microstructures in situ by ultralow-frequency Raman spectroscopy.

Ultralow-frequency Raman spectroscopy that can measure vibrational bands at as low as ±10 cm(-1) has enabled facile in situ imaging of polycrystalline microstructures such as grains and grain boundaries with high polymorph specificity. We demonstrate this method by investigating microcrystals of two distinct polymorphs of 1,1'-binaphthyl using a microscope.

In vivo live cell imaging for the quantitative monitoring of lipids by using Raman microspectroscopy.

A straightforward in vivo monitoring technique for biomolecules would be an advantageous approach for understanding their spatiotemporal dynamics in living cells. However, the lack of adequate probes has hampered the quantitative determination of the chemical composition and metabolomics of cellular lipids at single-cell resolution. Here, we describe a method for the rapid, direct, and quantitative determination of lipid molecules from living cells using single-cell Raman imaging.