The aim of this study is to develop a near-infrared spectroscopy (NIRS)-based system that recognizes pleasant and unpleasant human emotions based on cerebral blood flow (CBF) in order to understand the minds of patients whose brain function is severely impaired. The forehead region is easily accessible to NIRS measurements, whereas the role of the anterior prefrontal cortex (PFC) in the processing of emotion remains to be elucidated. METHODSInitially, using event-related NIRS we examined changes in oxygenated hemoglobin (oxyHb) as an indicator of regional CBF changes, which reflect brain activity directly related to emotions, but not to cognitive operations in the anterior frontal regions, during viewing affective pictures. The event-related potentials (ERPs), systemic blood pressure, and pulse rate were also measured simultaneously. RESULTSThe event-related analysis of changes in oxy-Hb for a 6 s-picture presentation period showed that very unpleasant emotion was accompanied by an increase in oxy-Hb in the bilateral ventrolateral PFCs, while very pleasant emotion was accompanied by a decrease in oxy-Hb in the left dorsolateral PFC. There were no significant differences in either ERPs or autonomic nervous system activities between the two emotional states. CONCLUSIONThese findings suggest the possibility of recognizing patients' emotions from CBF changes.

Although SERS spectroscopy, which is sensitive to molecular vibration states, offers label-free visualization of molecules, identification of molecules and their reliable large-area imaging remains to be developed. Limitation comes from difficulties in fabricating a SERS-active substrate with homogeneity over a large area. Here, we overcome this hurdle by utilizing a self-assembled nanostructure of boehmite that is easily achieved by a hydrothermal preparation of aluminum as a template for subsequent gold (Au) deposition. This approach brought about random arrays of Au-nanostructures with a diameter of ∼125 nm and a spacing of <10 nm, ideal for the hot-spots formation. The substrate, which we named "gold nanocoral" (GNC) after its coral reef-like shape, exhibited a small variability of signal intensities (coefficient value <11.2%) in detecting rhodamine 6G molecule when 121 spots were measured over an area of 10 × 10 mm(2), confirming high uniformity. The transparent nature of boehmite enabled us to conduct the measurement from the back-side of the substrate as efficiently as that from the front-side. We then conducted tissue imaging using the mouse ischemic brain adhered on the GNC substrate. Through nontargeted construction of two-dimensional-Raman-intensity map using differential bands from two metabolically distinct regions, that is, ischemic core and contralateral-control areas, we found that mapping using the adenine ring vibration band at 736 cm(-1) clearly demarcated ischemic core where high-energy adenine phosphonucleotides were degraded as judged by imaging mass spectrometry. Such a detection capability makes the GNC-based SERS technology especially promising for revealing acute energy derangement of tissues.

Gold deposition with diagonal angle towards boehmite-based nanostructure creates random arrays of horse-bean-shaped nanostructures named gold-nanofève (GNF). GNF generates many electromagnetic hotspots as surface-enhanced Raman spectroscopy (SERS) excitation sources, and enables large-area visualization of molecular vibration fingerprints of metabolites in human cancer xenografts in livers of immunodeficient mice with sufficient sensitivity and uniformity. Differential screening of GNF-SERS signals in tumours and those in parenchyma demarcated tumour boundaries in liver tissues. Furthermore, GNF-SERS combined with quantum chemical calculation identified cysteine-derived glutathione and hypotaurine (HT) as tumour-dominant and parenchyma-dominant metabolites, respectively. CD44 knockdown in cancer diminished glutathione, but not HT in tumours. Mechanisms whereby tumours sustained HT under CD44-knockdown conditions include upregulation of PHGDH, PSAT1 and PSPH that drove glycolysis-dependent activation of serine/glycine-cleavage systems to provide one-methyl group for HT synthesis. HT was rapidly converted into taurine in cancer cells, suggesting that HT is a robust anti-oxidant for their survival under glutathione-suppressed conditions.

COMMUNICATIONnanoparticle distance using stimuli-responsive polymers, [ 25,26 ] elastomers, [ 27 ] and DNA [ 28,29 ] have been developed. However, the structures formed using these approaches differ from that of the ideal SERS substrate, which has an extensive regular structure, as described above. Although there is a report on SERS substrates in which gap distance can uniformly change, it did not show the enhancement of trapping effi ciency of large molecules by active gap control. [ 30 ] To address this issue, we have fabricated tunable plasmonic nanostructures with a highly ordered structure through the combination of the self-assembled gold nanoparticles (GNPs) and the use of a hydrogel as a substrate. In our previous report, we demonstrated the transfer of gold dot patterns, fabricated by photolithography and electron-beam lithography, and confi rmed changes in the interval between dots by volume change in the gel. [ 31 ] This result indicates that the gap distance in the GNP-assembled fi lm can be controlled on the gel. Our approach in this study is shown in Scheme 1 . Here, we demonstrate that active gap distance control using tunable plasmonic substrates can signifi cantly intensify the SERS signals of proteins. Therefore, we propose the use of an open-to-closed system for active gap distance control for the sensitive detection of biomacromolecules by SERS.Highly ordered GNP thin fi lm was prepared using the cast method following our previous report. [ 32 ] GNPs (diameter: 20 nm) coated with fl uorinated tetraethylene glycol (FTEG) ligand were cast on piranha-cleaned glass or silicon substrates and dried under ambient conditions. The solvent quickly evaporated and a thin blue-colored fi lm was formed from a redcolored colloidal solution ( Figure 1 B-i, Figure S1A, Supporting Information). This color change resulted from the plasmon coupling effect due to the close proximity of the GNPs. The extinction spectra of this colloidal solution and thin fi lm showed a plasmonic peak shift of ≈90 nm ( Figure S1B, Supporting Information). Atomic force microscopic (AFM) images of the GNP thin fi lm showed that GNPs formed a well-packed, mostly mono-layered, structure with minimum defects on the solid substrates ( Figure S1C, Supporting Information). Scanning electron microscope (SEM) observation of the GNP fi lm prepared on a supported carbon membrane for transmission electron microscopy gave a clear image showing that the interparticle (center-to-center) distance and the gap distance were ≈20.5 nm and ≈1.5 nm, respectively ( Figure S1D, Supporting Information).Transfer of the GNP thin fi lms onto gels was performed by in situ polymerization on the substrates (Figure 1 A). [ 31 ] Molds A surface plasmon resonance is a coherent oscillation of the surface conduction electrons excited by electromagnetic radiation. Research on such light-metal interactions, which are known as plasmonics, has attracted a great deal of attention due to their potential applications in optical or photonic devices and sensors. [1][2][3][4] In...

We present large-area ultrathin metasurfaces that transmit visible light and reflect near-infrared (NIR) wavelengths. These visible-transparent metasurfaces consist of 10 nm-thick monolayer of randomly dispersed silver nanodisks, that is only λ/90 thickness at the reflection peak wavelength. Calculated optical properties of the structure show that the reflectance for NIR wavelengths increases monotonically as a function of increasing nanodisk density, while the absorption saturates and scattering of visible light decreases. We demonstrate that the proposed structure is easy to fabricate with chemically synthesized silver particles using the bottom-up method and has industrially applications.

Control over the orientation of metal nanorods is important for both fundamental and applied research. We show that gold nanorods (GNRs) can be aligned in a single direction by adsorbing positively charged GNRs onto a double-strand DNA-grafted substrate through electrostatic interaction. The ordered structure can be optimized by controlling the density of the positive charges on the surface of the GNRs. We found, in agreement with the results of theoretical simulation, that the resultant structure exhibits plasmonic properties that are dependent on the GNR orientation relative to the direction of an oscillating electric field. Our approach provides new insights into the polymer-assisted self-assembly of rod-shaped nanoparticles utilizing electrostatic interactions.

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The self-assembly of gold nanoparticles (GNPs) into a defined structure, particularly hollow capsule structures, provides great potential for applications in materials science and medicine. However, the complexity of the parameters for the preparation of those structures through self-assembly has limited access to critical mechanistic questions. With this in mind, we have studied GNP vesicle (GNV) formation through self-assembly by the surface modification of GNPs with low-molecular-weight ligands. Here, we successfully prepared GNVs composed of GNPs with a diameter of 30 nm by surface modification with carboxylic acid-terminated fluorinated oligo(ethylene glycol) ligands (CFLs). As the carboxylic acid has two states (protonated and deprotonated), the balance of the attraction and repulsion between GNPs covered with CFLs is tunable. Sodium carboxylate-terminated fluorinated oligo(ethylene glycol) ligands (SCFLs) provided smaller GNVs than did CFLs at 0.8 × 10 NPs/mL. Time-course study revealed that CFL-covered GNPs quickly form small aggregates and gradually grow to larger GNVs (ca. 200 nm), but no gradual growth was observed for SCFL-covered GNPs. This result indicated that the electrostatic repulsion inhibits fusion of the small GNVs. The size of the GNVs formed with the aid of CFLs was independent of the initial GNP concentration, but the extinction spectra were concentration-dependent. Electron microscopy imaging and simulations supported the defect formation in the assemblies. These results provided new insights into the vesicle formation mechanism.