Capillary Tube Surface-Enhanced Raman Scattering Substrate and High-Sensitivity Molecule Detection.

Surface-enhanced Raman scattering (SERS) greatly improves molecule sensitivity compared with ordinary Raman spectroscopy. To excite and detect SERS efficiently, we fabricated glass-made microcapillary tubes decorated with silver nanoparticles inside them. The capillary tubes work as sample containers, where the required sample volume is in the order of a few nanoliters. The capillary tubes also play the role of optical waveguides. The tubes guide the excitation laser light through them so that the light illuminates whole silver nanoparticles inside the tubes at once. The tubes guide the SERS light to the tube end efficiently. The decoration of silver nanoparticles inside the tubes was performed by the silver mirror reaction. By making the tubes thinner and longer, highly sensitive SERS spectroscopy can be achieved. Our method would be a powerful tool for high-sensitivity molecule detection where the sample volume and concentration are extremely low.

Ultrasmall all-optical plasmonic switch and its application to superresolution imaging.

Because of their exceptional local-field enhancement and ultrasmall mode volume, plasmonic components can integrate photonics and electronics at nanoscale, and active control of plasmons is the key. However, all-optical modulation of plasmonic response with nanometer mode volume and unity modulation depth is still lacking. Here we show that scattering from a plasmonic nanoparticle, whose volume is smaller than 0.001 µm(3), can be optically switched off with less than 100 µW power. Over 80% modulation depth is observed, and shows no degradation after repetitive switching. The spectral bandwidth approaches 100 nm. The underlying mechanism is suggested to be photothermal effects, and the effective single-particle nonlinearity reaches nearly 10(-9) m(2)/W, which is to our knowledge the largest record of metallic materials to date. As a novel application, the non-bleaching and unlimitedly switchable scattering is used to enhance optical resolution to λ/5 (λ/9 after deconvolution), with 100-fold less intensity requirement compared to similar superresolution techniques. Our work not only opens up a new field of ultrasmall all-optical control based on scattering from a single nanoparticle, but also facilitates superresolution imaging for long-term observation.

Size dependent nanomechanics of coil spring shaped polymer nanowires.

Direct laser writing (DLW) via two-photon polymerization (TPP) has been established as a powerful technique for fabrication and integration of nanoscale components, as it enables the production of three dimensional (3D) micro/nano objects. This technique has indeed led to numerous applications, including micro- and nanoelectromechanical systems (MEMS/NEMS), metamaterials, mechanical metamaterials, and photonic crystals. However, as the feature sizes decrease, an urgent demand has emerged to uncover the mechanics of nanosized polymer materials. Here, we fabricate coil spring shaped polymer nanowires using DLW via two-photon polymerization. We find that even the nanocoil springs follow a linear-response against applied forces, following Hooke's law, as revealed by compression tests using an atomic force microscope. Further, the elasticity of the polymer material is found to become significantly greater as the wire radius is decreased from 550 to 350 nm. Polarized Raman spectroscopy measurements show that polymer chains are aligned in nanowires along the axis, which may be responsible for the size dependence. Our findings provide insight into the nanomechanics of polymer materials fabricated by DLW, which leads to further applications based on nanosized polymer materials.

Direct laser writing of 3D architectures of aligned carbon nanotubes.

Direct laser writing through two-photon polymerization lithography is used to fabricate 3D nanostructures containing aligned single-wall carbon nanotubes (SWCNTs). SWCNTs are aligned in the laser scanning directions while they are embedded in the structure. The alignment is induced by spatial confinement, volume shrinkage, and the optical gradient force. This method is expected to lead to new applications based on aligned SWCNTs.

Combined intra-arterial infusion and systemic chemoradiotherapy for stage IV squamous cell carcinoma of the mandibular gingiva.

PURPOSE: The purpose of this study was to show the effectiveness of combining intra-arterial infusion and systemic chemotherapy with concurrent radiotherapy for treatment of stage IV mandibular gingival cancer. MATERIALS AND METHODS: A total of 23 patients with mandibular gingival cancer were treated with either docetaxel by intra-arterial infusion followed by systemic chemoradiotherapy with cisplatinum and 5-fluorouracil as a monthly regimen, or with docetaxel and cisplatinum by intra-arterial infusion followed by systemic chemoradiotherapy with 5-fluorouracil as a weekly or biweekly regimen. Tumor responses, locoregional control, overall survival, disease-specific survival, and adverse events were evaluated. RESULTS: Of the 23 patients enrolled in the study, 22 completed the treatment. With regard to clinical stages, 82 % were diagnosed as IVA and 18 % IVB. Complete and partial response was observed in 82 and 18 %, respectively. Five-year overall survival, disease-specific survival, and locoregional control were 51, 70, and 72 %, respectively. No statistically significant difference was seen between the monthly regimen and the weekly plus biweekly regimen, although the latter resulted in longer survival and 88 % control. CONCLUSION: Combined intra-arterial infusion and systemic chemoradiotherapy may be an effective treatment for patients with stage IV mandibular gingival cancer.

Laser fabrication of Au nanorod aggregates microstructures assisted by two-photon polymerization.

We demonstrate fabrication of Au nanorod aggregates microstructures by means of a femtosecond near-infrared laser. 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.

Size-dependent behaviors of femtosecond laser-prototyped polymer micronanowires.

A remarkable recent progress in two-photon photopolymerization is the achievement of fabrication resolution around tens of nanometers, establishing a femtosecond laser as a nanofabrication tool. However, how the superresolution has been made possible is still under arguement. We propose a concept of polymer network permeability to solvents, meaning a structure-loosened nanopolymer state that allows free penetration of small molecules to interpret the mechanism. Experimentally, we found proof showing existence of the state, including an unusually large volume shrinkage rate (>60%), shape-memory effect, a giant softness of nanospring, and the mechanical stability of rinsed two-photon written polymer nanowires.

[Re-evaluation of clinical utility of throat swab specimens for a rapid influenza diagnostic test].

Throat swab specimens collected from 439 patients with influenza-like symptoms visiting a clinic in the 2004-2005 influenza season were subjected to cell culture virus isolation and viral antigen detection using a rapid diagnostic kit, QuickVue Rapid SP influ (Quidel Corporation, San Diego, CA, U.S.A.). The sensitivity and specificity of diagnostic kit results were analyzed based on cell culture results, considered the diagnostic standard. Kit sensitivity was 87.8% (72/82) and specificity 90.2% (322/357) for type A influenza, and 80.4% (176/219) and 95.0% (209/220) for type B influenza, roughly comparable to results reported so far for nasopharyngeal swabs and/or nasal aspirates. Sensitivity and specificity calculated separately dividing patient age but no significant difference was seen. The antigen-detection kit thus appears clinically useful in diagnosing influenza, provided that is collected and processed properly.

Selective aggregation of single-walled carbon nanotubes using the large optical field gradient of a focused laser beam.

We demonstrate the selective aggregation of single-walled carbon nanotubes by photon forces, using the large optical field gradient of a laser focused through a high numerical aperture objective lens. The nanotubes, dispersed in an aqueous solution with a surfactant, are detected via Raman scattering from the confocal volume of the optical trap. By using a visible-light laser for both trapping and detection, the dynamics of the radial breathing mode signal taken at short intervals shows an increase of a single breathing mode over time, indicating the increase in the density of only one species of tube in the focal volume. This result represents a significant step toward the development of techniques for the arbitrary manipulation and sorting of nanotubes by optical fields.

Manipulating full photonic band gaps in two dimensional birefringent photonic crystals.

The probability to realize a full photonic band gap in two-dimensional birefringent photonic crystals can be readily manipulated by introducing symmetry reduction or air holes in the crystal elements. The results lie in either creation of new band gaps or enlargement of existing band gaps. In particular, a combination of the two processes produces an effect much stronger than a simple summation of their individual contributions. Materials with both relatively low refractive index (rutile) and high refractive index (tellurium) were considered. The combined effect of introduction of symmetry reduction and air holes resulted in a maximum enlargement of the band gaps by 8.4% and 20.2%, respectively, for the two materials.

Two-photon induced polymer nanomovement.

We present the first report of two-photon induced plastic surface deformation in solid polymer films. Exposure of azo polymer films, which absorb in the visible range (lambda(max) = 480 nm), to intense 920 nm irradiation leads to polarization dependent photofluidic polymer nanomovement caused by photoselective two-photon trans <-->cis isomerization. The deformations were induced by a gradient of light intensity; and strongly depend on the wavelength and the polarization direction of the incident laser light and the position of the focused spot with respect to the plane of the polymer film.

Size dependence of transition temperature in polymer nanowires.

We studied the effect of changing temperature on the mechanical properties of nanosized poly(methyl methacrylate) wires fabricated by two-photon fabrication. At around room temperature, the nanowires showed a transition temperature where the shear modulus suddenly changed. This transition temperature was observed to decrease more than 40 K by decreasing the radius of the nanowires from 450 to 150 nm. This size is several times larger in nanowires than reported values of polymer thin film thickness showing a depression of the glass transition temperature.

Two- and three-dimensional micro/nanostructure patterning of CdS-polymer nanocomposites with a laser interference technique and in situ synthesis.

Two- and three-dimensional (2D and 3D) micro/nanostructures of CdS-polymer nanocomposites have been successfully patterned, combining photopolymerization via a laser four-beam interference technique with in situ synthesis of CdS nanoparticles in the patterned polymer matrix. The morphology and optical properties of CdS nanoparticles in polymer matrices have been confirmed using TEM, XRD, FTIR, UV-vis absorption and fluorescence spectroscopy. Laser irradiation time and film thickness are certified to be the key factors for the control of the micro/nanostructures. With thickening film, the fabricated microstructures of CdS-polymer nanocomposites were dramatically changed from 2D rods to 3D networks which were composed of nanofibres, nanometre-scale walls and micrometre-scale rods. These kinds of 2D and 3D micro/nanostructures could be expected as potential applications in the development of nanotechnology, such as nanomedical systems, micro-fluidic chips, nanoreactors and micro/nanopurification or separation systems.

Multi-step multi-beam laser interference patterning of three-dimensional photonic lattices.

We present laser interference patterning of three-dimensional photonic lattice structures with three-step three-beam irradiation. In contrast to one-step four-beam interference patterning, the proposed method makes it possible to continuously tune the lattice constant and the photonic band gap without distortion of the lattice shape. We analytically show that all fourteen Bravais lattices are possible to be produced by choosing proper incident vectors of laser beams. A simple routine to seek the geometrical configuration of the incident beams for producing arbitrary Bravais lattices is shown. Furthermore, We experimentally demonstrate the fabrication of three-dimensional photonic lattices in the photoresist SU-8. Significant photonic band gap effects have been observed from the well-defined photonic lattices.

Direct laser writing defects in holographic lithography-created photonic lattices.

As a well-established laser fabrication approach, holographic lithography, or multibeam interference patterning, is known for its capability to create long-range ordered large-volume photonic crystals (PhCs) rapidly. Its broad use is, however, hampered by difficulty in inducing artificially designed defects for device functions. We use pinpoint femtosecond laser ablation to remove and two-photon photopolymerization to add desired defective features to obtain photonic acceptors and photonic donors, respectively, in an otherwise complete PhC matrix produced by holographic lithography. The combined use of the two direct laser writing technologies would immediately make holographic lithography a promising industrial tool for PhC manufacture.

Self-written waveguides in photopolymerizable resins.

We study the optically induced growth and interaction of self-written waveguides in a photopolymerizable resin. We investigate experimentally how the interaction depends on the mutual coherence and the relative power of the input beams and suggest an improved analytical model that describes the growth of single waveguides and the main features of their interaction in photosensitive materials.

In vitro antimicrobial activity and penetration rate into sputum of gatifloxacin, a novel 6-fluoro-8-methoxy quinolone, and its therapeutic efficacy in respiratory infections.

The in vitro antimicrobial activity of gatifloxacin against clinical isolates of pathogenic bacteria was evaluated. Minimum inhibitory concentrations of gatifloxacin, ofloxacin, ciprofloxacin, tosufloxacin, sparfloxacin, and rifampicin against 20 strains each of methicillin-susceptible Staphylococcus aureus, methicillin-resistant Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Serratia marcescens, and Pseudomonas aeruginosa, 18 strains of Enterobacter cloacae, 15 strains each of Streptococcus Pneumoniae and Moraxella catarrhalis, 12 strains of Haemophilus influenzae, 18 strains of Mycobacterium intracellulare, and 22 strains each of Mycobacterium tuberculosis and Mycobacterium avium were determined. The minimum inhibitory concentrations90's of gatifloxacin against the above species were 0.12, 8, <==0.06, 0.5, 2, 2, <==0.06, 0.39, 0.05, 0.013, 2, 0.5, and 4 &mgr;g/ml, respectively. Gatifloxacin was four times as active as ofloxacin against methicillin-susceptible and -resistant Staphylococcus aureus, and as active as ofloxacin against Enterobacteriaceae and Pseudomonas aeruginosa. Gatifloxacin was as active as tosufloxacin and sparfloxacin against Streptococcus pneumoniae, Moraxella catarrhalis, and Haemophilus influenzae. The antimycobacterial activity of gatifloxacin was similar to that of sparfloxacin. Five patients with chronic respiratory infections and one patient with acute pneumonia received 100-400 mg/day of gatifloxacin orally for 5-12 days (mean, 8.17 days). The clinical effects were excellent in one patient and good in five. One strain of Haemophilus influenzae was eradicated and one strain of Pseudomonas aeruginosa persisted after therapy. Adverse reactions were mild and improved after completion of therapy. In one patient with chronic bronchitis, the maximum sputum concentrations 2-4 h after oral administration of 150 mg of gatifloxacin on days 1 and 6 were 0.88 and 1.45 &mgr;g/ml, respectively, and in serum the values were 0.84 and 1.24 &mgr;g/ml, respectively. Thus it was found that gatifloxacin possesses potent activity against respiratory pathogens (including Mycobacteriaceae), and shows good penetration rate into sputum, and that it can be used as the drug of first choice in the treatment of respiratory tract infections.

Comparative in vitro activity of carbapenem antibiotics against respiratory pathogens isolated in recent years.

We investigated the antibacterial activity of 12 antibiotics, including 4 carbapenems, against 200 strains of respiratory pathogens isolated in 1997, and compared the results with those obtained in 1993. The strains examined were 38 strains of methicillin-susceptible Staphylococcus aureus (MSSA), 32 strains of methicillin-resistant S. aureus (MRSA), 22 strains of penicillin-susceptible Streptococcus pneumoniae (PSSP), 10 strains of penicillin-resistant S. pneumoniae (PRSP), 53 strains of Pseudomonas aeruginosa, 19 strains of Moraxella catarrhalis, and 26 strains of Haemophilus influenzae. In 1993, 100 strains were examined. The minimal inhibitory concentration data of the present study showed that imipenem and panipenem were more active than the other agents against gram-positive bacteria, and that meropenem and biapenem were more active than the other agents against gram-negative bacteria. By comparing these results with those obtained in 1993, it was found that increase of resistance to carbapenem antibiotics was not observed against all the strains tested in this study. Thus, it can be stated that carbapenem antibiotics retain their position as the drug of first choice for severe infections.