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Reseach 2011-2012

Dynamic SERS imaging inside a living cell is demonstrated with the use of a gold nanoparticle, which travels through the intracellular space to probe local molecular information over time. Simultaneous tracking of particle motion and SERS spectroscopy allows us to detect intracellular molecules at 65 nm spatial resolution and 50 ms temporal resolution, providing molecular maps of organelle transport and lisosomal accumulation. Multiplex spectral and trajectory imaging will enable imaging of specific dynamic biological functions such as membrane protein diffusion, nuclear entry, and rearrangement of cellular cytoskeleton.

Dynamic SERS Imaging of Cellular Transport Pathways with Endocytosed Gold Nanoparticles
Jun Ando, Katsumasa Fujita, Nicholas I. Smith, and Satoshi Kawata
Nano Lett. 2011, 11, 5344-5348

FE-SEM image taken after rising the sample with supercritical CO2.

(a) Emission spectra from the cell applied with a sinusoidal electric field (160 V/μm, 600.0 Hz) with various phase shiftings, (b) slope efficiency characteristics of the laser with and without electric field, and (c) demonstration of wavelength-swept lasing from the ChLC film.

Wavelength tuning was demonstrated in a cholesteric liquid crystal based on refractive index modulation. A simple fabrication method in which a network of nano pores is formed in a photo polymerized ChLC film was presented, and wavelength-swept lasing from a single free standing film was demonstrated. These nano composite films are potentially useful to realize ultra compact wavelength swept lasers.

Tunable Lasing from a Cholesteric Liquid Crystal Film Embedded with a Liquid Crystal Nanopore Network

Yo Inoue, Hiroyuki Yoshida, Kenta Inoue, Yusuke Shiozaki, Hitoshi Kubo, Akihiko Fujii, and Masanori Ozaki

Advanced Materials Volume 23, 5498, published online:14 NOV 2011

Short (organicfluorophores MitoTracker Orange) and long (lanthanides TPA-Eu) lifetime PL components were drawn with different pseudocolors (pseudo color: green for prompt PL and red for delayed PL). Scale bar: 50  μ m.
We designed and synthesized a novel luminescent europium(III) complex probe, TPA-Eu. Combined with TRL microscopy, we could separate live-cell imaging from background autofluorescence. The long-lifetime PL of TPA-Eu labels on cell surface proteins can be selectively detected even in the presence of FBS. The covalent probe labeling enabled long time-lapse imaging lasting at least several hours. Both of these virtues are quite valuable especially for in vivo imaging experiments, because the autofluorescence of animal bodies severely hampers detection of faint PL signals, and in vivo studies usually take at least several hours. For further applications, intracellular protein labeling may be desired. As we expected from the anionic structure, TPA-Eu did not permeate into living cells. More hydrophobic or cationic lanthanide complexes should be chosen for intracellular protein labeling.
We also demonstrated a unique application—lifetime based multicolor imaging—by exploiting pulse-gating technology. This multicolor imaging system would yield almost the same data as multicolor fluorescence imaging with different filter sets. Because this technique is orthogonal to the conventional wavelength-based multicolor imaging, simultaneous use of both wavelength-based and lifetimebased multicolor imaging techniques could increase the number of color channels. For example, three emission filter sets (blue, green, and red) and two lifetime settings (short and long) yield six channels. Considering that differently colored luminescent lanthanides such as terbium(III) or dysprosium(III) are also suitable for TRL measurements, simultaneous imaging of a larger number of proteins can be achieved in future.

Covalent Protein Labeling with a Lanthanide Complex and Its Application to Photoluminescence Lifetime-Based Multicolor Bioimaging

Shin Mizukami, Taku Yamamoto, Akimasa Yoshimura, Shuji atanabe, Kazuya Kikuchi
Angewandte Chemie International Edition Volume 50, Issue 37, pages 8750–8752, September 5, 2011
SEM images of Au nanorods/PMMA aggregated spots produced at a stationary focused spot of Ti:sapphire laser light. The laser intensity was 1.5 GW/cm2 and the exposure time was (a) 7.5 s and (b) 10 s, respectively. (c) High magnification image of (b). The spot consisted of Au nanorods individually wrapped by a PMMA layer. (d) Hypothetical mechanism of the formation of Au nanorods aggregation.

Fabrication of Au nanorod aggregates microstructures by means of 
a femtosecond near-infrared laser is demonstrated. The laser 
light was tightly focused into colloidal Au nanorods dispersed 
in photopolymerizable metyl-methacrylate (MMA) compound to 
induce two-photon polymerization (TPP). TPP of MMA glued the 
nanorods together to form solid microstrucures of aggregates. 
The laser light excited a local surface plasmon, resulting in 
confinement of TPP in the vicinity of nanorods. Concurrenly 
occurring optical accumulation of nanorods created a unique 
mechanism for the formation of nanorod aggregates into desired 
microstructures. This technique would be a clue for a novel 
micro/nanofabrication method for plasmonic materials and devices.

Laser fabrication of Au nanorod aggregates microstructures assisted by two-photon polymerization
Masui K, Shoji S, Asaba K, Rodgers TC, Jin F, Duan XM, Kawata S.
22786 Nov 2011 VOL 19 OPTICS EXPRESS

the amount of center frequency shift is lineally increasing with each input peak power

We report the attempt of optical quantization and coding in 5-bit parallel format for photonic A/D conversion. The proposed system is designed to realize generation of 32 different optical codes in proportion to the corresponding signal levels when fed a certain range of amplitude-varied input pulses to the setup. Optical coding in a bit-parallel format made it possible, that provides 5bit optical codes from 32 optical quantized pulses. The 5-bit parallel operation of an optical quantization and coding module with 5 multi-ports was tested in our experimental setup.

Five-bit parallel operation of optical quantization and coding for photonic analog-to-digital conversion
Tsuyoshi Konishi, Koji Takahashi, Hideki Matsui, Takema Satoh, and Kazuyoshi Itoh
OPTICS EXPRESS/ 15 August 2011 Vol. 19,  No. 17 16106

Fluorescence images of a single FND with a diameter of approximately 100 nm. The fluorescence images were obtained by demodulation at the fundamental frequency (a, 10 kHz) and the harmonic frequencies (b, 20 kHz), (c, 30 kHz), and (d, 40 kHz). 

Fluorescence images of FNDs and mitochondria in macrophages in the focal plane (x-y image). a) Dual-color image constructed with a confocal image of mitochondria and a SAX image of FNDs, b) mitochondria and FNDs imaged simultaneously without SAX, c) confocal and d) SAX image of FNDs after bleaching the mitochondria staining dye. The distribution of mitochondria in a) was obtained by subtracting c) from b). 
The combination of SAX microscopy and FNDs is a powerful technique to image the distribution of particles taken into cells with high spatial resolution.
We report the use of fluorescent nanodiamonds (FNDs) as a photostable fluorescent probe for high resolution saturated excitation (SAX) microscopy. We confirmed that FNDs show a nonlinear fluorescence response under saturated excitation conditions generated by intense excitation light. Using FNDs, we quantified the spatial resolution improvement inherent in SAX microscopy, and experimentally demonstrated the scalability of the spatial resolution of SAX microscopy.
For improving the spatial resolution while keeping the temporal resolution, a FND possessing a larger absorption cross-section and a shorter fluorescence lifetime is desirable since it would allow rapid cycling of fluorescence excitation and emission, resulting an increase in the number of fluorescence photons detectable in a unit time. The photostability of the FNDs allowed us to perform nanoparticle imaging of a multicolor-stained macrophage cell with a spatial resolution beyond the diffraction limit.

SAX microscopy with fluorescent nanodiamond probes for high-resolution fluorescence imaging
Masahito Yamanaka, Yan-Kai Tzeng, Shogo Kawano, Nicholas I. Smith, Satoshi Kawata, Huan-Cheng Chang, and Katsumasa Fujita
Biomedical Optics Express, Vol. 2, Issue 7, pp. 1946-1954 (2011)

We are developing organic thin-film solar cells utilizing low-weighted molecular semiconductors. Bulk hetero junction solar cells utilizing soluble phthalocyanine derivative, C6PcH2 (1,4,8,11,15,18,22,25-octahexylphthalocyanine) were investigated. The active layer was fabricated by spin-coating the mixed solution of C6PcH2 and PCBM, and active layer thickness dependence was investigated, and the optimized active layer thickness was clarified to be 120 nm. By inserting MoO3 hole transport buffer layer between the positive electrode and active layer, the fill factor and energy conversion efficiency were improved to be 0.50 and 3.2%, respectively. The tandem organic thin-film solarcell was also fabricated utilizing active layer materials of C6PcH2 and P3HT and the interlayer of LiF/Al/MoO3 structure, and a high open-circuit voltage of 1.27 V was achieved.

Bulk heterojunction organic solar cells utilizing 1,4,8,11,15,18,22,25-octahexylphthalocyanine
Tetsuro Hori, Naoki Fukuoka, Tetsuya Masuda, Yasuo Miyake, Hiroyuki Yoshida, Akihiko Fujii, Yo Shimizu and Masanori Ozaki
Solar Energy Materials and Solar Cells, Vol. 95, No. 11, pp. 3087-3092, (2011)

A new holographic technique based on surface plasmons that can 
reconstruct true 3D color images, where the colors are reconstructed by satisfying resonance conditions of surface 
plasmon polaritons for individual wavelengths. Such real 3D 
color images can be viewed from any angle, just like the original object. The paper is introduced at many web cites as e. g. "Plasmons Create Beautiful Full-Color Holograms" and "Quantum 
effect fuels colour-fast holograms".

Surface-Plasmon Holography with White-Light Illumination
Miyu Ozaki, Jun-ichi Kato, and Satoshi Kawata
218 8 APRIL 2011 VOL 332 SCIENCE

Two-dimensional spectral images (6×52 pixels) of PE (a) and ES cells (b) and their profiles (c) (PE cells, blue; ES cells, red) along the line shown in their images. Images and profiles refer to 719-cm−1
(A) and 937-cm−1 (B) bands. The total exposure time was 120 s. 
Spectral intensity increases as follows: black<green<blue<purple<orange<white.
Scale bars, 5 μm.
Raman microspectroscopy (a laser Raman confocal microscope, RAMAN-11; Nanophoton, Osaka, has the capacity to detect the biochemical changes encountered with the early stages of embryonic stem (ES) cell differentiation. The Raman signature of 
primitive endoderm (PE) cells was distinguished from that of the ES cells. It was shown that the PE cells had reduced contents of nucleic acids, lipids, and carbohydrates and an elevated content of
proteins when compared with the undifferentiated ES cells.
Also, it was demonstrated that the most significant change was observed at 937 cm−1 (glycogen and proteins), and we identified the I1033/I937 intensity ratio as a significant Raman biomarker to distinguish between PE cells and undifferentiated ES cells. Finally, a population of relatively pure PE cells was identified in the core of Embryoid bodies (EBs) and which was attributed to the gathering of the scattered leftover PE cells, at the interior of the EBs, to 
receive the signal of selective death.

Discrimination of primitive endoderm in embryoid bodies
by Raman microspectroscopy

Maha A. El-Hagrasy & Eiichi Shimizu & Masato Saito &
Yoshinori Yamaguchi & Eiichi Tamiya

Anal Bioanal Chem DOI 10.1007/s00216-011-5554-6 November 2011

The enhancement of thermal radiation in the terahertz region is presented theoretically by using the spoof surface plasmon mode on the microcavity array. We found that the terahertz wave is radiated selectively in a vertical direction. As a result, a quasi-monochromatic terahertz source can be created.

Thermal radiation control in the terahertz region using the spoof surface plasmon mode
Yosuke Ueba, Junichi Takahara, and Tadao Nagatsuma

March 15, 2011 / Vol. 36, No. 6 / OPTICS LETTERS 909
EdU is readily incorporated into cellular DNA during DNA replication and accumulates in the nucleus.

Raman image obtained from HeLa cells treated with EdU by merging the images at 749, 2123, and 2849 cm-1, which were assigned to the blue, red, and green channels, respectively. The image acquisition time was 49 min.

The alkyne peak (2123 cm-1) was detected in the nucleus but not in the cytoplasm of HeLa cells treated with EdU.
We have achieved click-free visualization of the alkyne-tagged cell proliferation probe EdU by means of Raman microscopy. To our knowledge, this is the first example of direct imaging of an alkyne-modified molecule in living cells. The results demonstrate the potential of the alkyne moiety as an excellent Raman tag for live-cell imaging of small molecules. At least in the case of EdU, the ethynyl group is small enough not to affect the biological activity of the parent small molecule, and this result indicates that click-free imaging using Raman microscopy has the potential to be a powerful methodology for chemical biology research. It should be mentioned that the imaging speed of our approach could be further improved by application of nonlinear Raman techniques such as coherent anti-Stokes Raman scattering (CARS) and stimulated Raman scattering (SRS) microscopy. These efforts are just beginning, and Raman imaging of other small, alkyne-tagged molecules as well as the development of improved instrumentation is under way.

Imaging of EdU, an Alkyne-Tagged Cell Proliferation Probe, by Raman Microscopy
Hiroyuki Yamakoshi, Kosuke Dodo, Masaya Okada, Jun Ando, Almar Palonpon, Katsumasa Fujita, Satoshi Kawata, and Mikiko Sodeoka

J. Am. Chem. Soc., 2011, 133 (16), 6102-6105

Alzheimer's disease (AD) is marked by the accumulation of neuronal plaques from insoluble amyloid-beta (Aβ) peptides. Growing evidence for the role of Aβ oligomers in neuronal cell cytotoxicity and pathogenesis has prompted the development of novel techniques to better understand the early stages of aggregation. Near infrared (NIR) optical trapping was applied to characterize the early stages of Aβ aggregation in the presence of a β-sheet intercalating dye, Congo Red (CR), as the fluorescent marker. The integration of fluorescence analysis with NIR optical trapping has provided a new outlook into the first two hours of Aβ aggregation.

Optical trapping for the characterization of amyloid-beta aggregation kinetics
J. Veloso, Hiroyuki Yoshikawa, Xin R. Cheng, Eiichi Tamiya and Kagan Kerman 

Analyst, 2011, 136, 4164-4167

The atomically monodisperse Pt5 nanocluster has low cytotoxicity and a fluorescence quantum yield of 18 %. Furthermore, it can be used as a fluorescent probe for cellular imaging (see picture; gray sphere: Pt5 nanocluster; PAMAM (G4-OH): fourth-generation polyamidoamine dendrimer; scale bar 20 μm).

Fluorescent Platinum Nanoclusters: Synthesis, Purification, Characterization, and Application to Bioimaging
Shin-Ichi Tanaka, Jun Miyazaki, Dhermendra K. Tiwari, Takashi 
Jin, and Yasushi Inouye

Angew. Chem. Int. Ed. 2011, 50, 431 –435
Typical Raman map of adenine (10−9 M) (left), corresponding optical microscopic image (middle), and their overlay
image (right).
We report a large-scale, free standing and chemically stable SERS substrate for both resonant and nonresonant single molecule detection. Our robust substrate is made from wrinkled nanoporousAu79Ag21 films that contain a high number of electromagnetic "hot spots" with a local SERS enhancement larger than 109.

Single molecule detection from a large-scale SERS-active Au79Ag21 substrate
Hongwen Liu,  Ling Zhang, Xingyou Lang, Yoshinori Yamaguchi,     Hiroshi Iwasaki,  Yasushi Inouye, Qikun Xue & Mingwei Chen

Scientific Reports 1, Article number: 112 doi:10.1038/srep00112

The carrier mobility of octahexylphthalocyanine (C6PcH2) in the crystal phase (the hexagonal disordered columnar (Colhd) mesophase) was found to be strong negative temperature dependent for the hole mobility: a maximum drift mobility of 1.4 cm2·V-1·s-1 at -15 °C and smaller T dependent and a maximum mobility of 0.5 cm2·V-1·s-1 for the electrons.

High Carrier Mobility up to 1.4 cm2·V-1·s-1in Non-Peripheral Octahexyl Phthalocyanine
Yasuo Miyake, Youyu Shiraiwa, Keizo Okada, Hirosato Monobe, Tetsuro Hori, Naoyuki Yamasaki, Hiroyuki Yoshida, Michael J. Cook, Akihiko Fujii, Masanori Ozaki, and Yo Shimizu

Appl. Phys. Express 4 (2011) 021604 (3 pages)

ヘリウム大気圧低周波プラズマジェットにより活性種が生成され液中に02 ̄・が拡散しHOO・が生じて高い殺菌力が得られる。

プラズマ消毒治療のための液中殺菌技術とその物理化学モデル    北野勝久、 井川 聡、 谷 篤史

化学工学 75 p.356-358, 2011