Rapid, High-Resolution 3D Interference Printing of Multilevel Ultralong Nanochannel Arrays for High-Throughput Nanofluidic Transport.

3D interference printing enables the single-step production of multilayered ultralong nanochannel arrays with nanoscale regularity. The superior depth-of-focus of this technique realizes a state-of-the-art nanostructure which has intensively stacked 32 layers of inch-long, horizonontal nanochannels with sub-100 nm holes in a monolithic matrix (≈15 µm). This exceptional structure can be integrated into microfluidic devices, facilitating high-flux rheological platforms using nanocapillarity.

Identification of metalloporphyrins with high sensitivity using graphene-enhanced resonance Raman scattering.

Graphene-enhanced resonance Raman scattering (GERRS) was performed for the detection of three different metallo-octaethylporphyrins (M-OEPs; M = 2H, FeCl, and Pt) homogeneously thermal vapor deposited on a graphene surface. GERRS of M-OEPs were measured using three different excitation wavelengths, λ(ex) = 405, 532, and 633 nm, and characterized detail vibrational bands for the identification of M-OEPs. The GERRS spectra of Pt-OEP at λ(ex) = 532 nm showed ~29 and ~162 times signal enhancement ratio on graphene and on graphene with Ag nanoclusters, respectively, compared to the spectra from bare SiO2 substrate. This enhancement ratio, however, was varied with M-OEPs and excitation wavelengths. The characteristic peaks and band shapes of GERRS for each M-OEP were measured with high sensitivity (100 pmol of thermal vapor deposited Pt-OEP), and these facilitate the selectively recognition of molecules. Also, the peaks shift and broadening provide the evidence of the interaction between graphene and M-OEPs through the charge transfer and π-orbital interaction. The increase of graphene layer induced the decrease of signal intensity and GERRS effect was almost not observed on the thick graphite flakes. Further experiments with various substrates demonstrated that the interaction of single layer of graphene with molecule is the origin of the Raman signal enhancement of M-OEPs. In this experiment, we proved the graphene is a good alternative substrate of Raman spectroscopy for the selective detection of various metalloporphyrins with high sensitivity.

Scalable functionalized graphene nano-platelets as tunable cathodes for high-performance lithium rechargeable batteries.

High-performance and cost-effective rechargeable batteries are key to the success of electric vehicles and large-scale energy storage systems. Extensive research has focused on the development of (i) new high-energy electrodes that can store more lithium or (ii) high-power nano-structured electrodes hybridized with carbonaceous materials. However, the current status of lithium batteries based on redox reactions of heavy transition metals still remains far below the demands required for the proposed applications. Herein, we present a novel approach using tunable functional groups on graphene nano-platelets as redox centers. The electrode can deliver high capacity of ~250 mAh g⁻¹, power of ~20 kW kg⁻¹ in an acceptable cathode voltage range, and provide excellent cyclability up to thousands of repeated charge/discharge cycles. The simple, mass-scalable synthetic route for the functionalized graphene nano-platelets proposed in this work suggests that the graphene cathode can be a promising new class of electrode.

DNA detection using a light-emitting polymer single nanowire.

Functionalization of light-emitting poly(3-methylthiophene) (P3MT) nanowires (NWs) with probe-DNA (p-DNA) and their label-free recognition of target-DNA (t-DNA) were correlated quantitatively with both the photoluminescence (PL) color and intensity of P3MT NWs.

Light-emitting color barcode nanowires using polymers: nanoscale optical characteristics.

We report on the light-emitting color barcode nanowires (LECB-NWs), which were fabricated by alternating the electrochemical polymerization of light-emitting polymers with various luminescence colors and efficiencies. The nanoscale photoluminescence characteristics of LECB-NWs were investigated using a laser confocal microscope with a high spatial resolution. The alternating light emissions of the LECB-NWs showed orange-yellow, red, and green colors due to the serial combination of poly(3-butylthiophene), poly(3-methylthiophene), and poly(3,4-ethylenedioxythiophene), respectively, with distinct luminescence intensities. The optical detection sensitivity and stability of LECB-NWs have been enhanced through a nanoscale Cu metal coating onto the NWs, based on surface plasmon resonance coupling and protection against oxidation. The flexibility of the LECB-NWs has been investigated through the folding and unfolding of the NWs by an applied nanotip impetus. The flexible LECB-NWs can be used as highly sensitive optical identification nanosystems for nanoscale or microscale products with complex physical shapes.

Dry etching of colloidal crystal films.

Two types of non-close-packed colloidal crystal films were prepared by etching the films made of polystyrene nanospheres using a hyperthermal neutral beam of oxygen gas. Etching without sintering above glass transition temperature of the polymer particles resulted in the non-close-packed structure of the nanospheres, in which polystyrene nanospheres in different lattice planes touched each other due to the reduction in the size of the nanospheres that occurred during the etching process. In contrast, a different non-close-packed structure with inter-connecting networks between etched nanospheres was generated by annealing of the colloidal crystal and a subsequent etching process. The photonic bandgap could be tuned during this dry etching of colloidal photonic crystals. This connected open structure could be used as a template for a silica inverse opal by chemical vapor deposition. An alternative dry etching process, reactive ion etching, mainly affected the morphology of particles near the top surface, and only a slight change in the stop band position of the colloidal crystal film was observed.

Photoluminescence characteristics for hybrid nanotubes of light emitting poly(3-methylthiophene) coated with copper: fluorescence effect.

The enhanced nanometer-scale photoluminescence (PL) and quantum yield of hybrid double layered nanotubes (HDLNTs) consisting of a light-emitting poly(3-methylthiophene) (P3MT) nanotube coated with nanometer-scale copper (Cu) metal were observed and presented. The HDLNTs of the Cu coated P3MT (P3MT/Cu) were synthesized through a sequential electrochemical synthetic method in an anodic alumina oxide (Al2O3) nanoporous template. We confirmed that the Cu nanotubes were covered outside the light emitting P3MT nanotubes based a high resolution transmission electron microscope image. From laser confocal microscope (LCM) PL experiments of an isolated single strand of the P3MT nanotubes and of their HDLNTs, we observed a -100 times enhancement of the PL peak intensity for the HDLNTs of P3MT/Cu compared to that of the P3MT single nanotube, which was qualitatively confirmed through the measurement of the quantum yield. The energy and/or charge transfer effects in surface plasmon resonance contributed to the larger enhancement of the PL efficiency of the hybrid P3MT/Cu nanotubes. The PL decay life-time of the excitons of the P3MT nanotubes using a time resolved PL was not changed after the formation of the HDLNTs, implying that the PL enhancement of the hybrid nanotubes might have originated from fluorescence, not phosphorescence.

Complex nanoparticle of light-emitting MEH-PPV with Au: enhanced luminescence.

Complex nanoparticles (NPs) of poly(2-methoxy-5-(2'-ethylhexyloxy)-p-phenylene vinylene) (MEH-PPV) NP adsorbed with Au NPs (MEH-PPV/Au NPs) were fabricated through a reprecipitation method. The formation of MEH-PPV/Au NP complexes was confirmed through high-resolution transmission electron microscopy and Fourier transform infrared experiments. The laser confocal microscope photoluminescence (PL) efficiency of the complex MEH-PPV/Au single NP dramatically increased compared with that of the MEH-PPV single NP without Au NPs, which was directly confirmed through color charge-coupled device images. The enhanced PL efficiency of the MEH-PPV/Au NP complex might have originated from the energy transfer effect in a surface plasmon resonance coupling between a MEH-PPV NP and Au NPs. The strong local field enhancement due to nanogaps between Au NPs in the background of a light-emitting MEH-PPV NP might be another origin of the PL enhancement of the NP complex, as supported by finite difference time domain calculations. We also observed the blue shift of the PL peaks of the single MEH-PPV and MEH-PPV/Au NP, compared with the solution PL peaks of those NPs.

Demonstration of high lateral resolution in laser confocal microscopy using annular and radially polarized light.

The authors present the experimental result of improved lateral resolution in laser confocal microscopy (LCM) by using annular and radially polarized light as the input illumination of an existing LCM. The authors examined the lateral resolution of the LCM by imaging a single fluorescent bead and measuring the lateral width of the single bead profile appearing in the optical image. Compared to no aperture and linearly polarized light, the central peak of the single bead profile narrowed by approximately 40%, being as small as 122 nm in full width at half maximum using 405 nm laser excitation in a reflection imaging. In addition, the authors showed that radial polarization helps to preserve the circular shape of the single bead profile whereas linearly polarized light tends to induce an elongation along the polarization direction.

Optical waveguiding of the nanowire/quantum dot hybrid system.

We present the results of optical waveguiding of nanowires/quantum dots hybrid systems which were made by depositing CdTe quantum dots (QDs) on ZnO nanowires (NWs). We used a laser confocal/atomic force combined microscope to image the QD photoluminescence caused by the light propagation along the NW/QD hybrid systems, and the nanoscale topographic images of the samples. The propagation lengths of the samples were estimated and shown to be consistent with measured thickness of the samples.

Connected open structures from close-packed colloidal crystals by hyperthermal neutral beam etching.

We report the fabrication of connected open structures from close-packed colloidal crystals by hyperthermal neutral beam etching. Colloidal crystal films of polystyrene microspheres were prepared by a vertical deposition method. Exposure of the colloidal crystal films to hyperthermal neutral beam made isolated microspheres in the face-centered cubic lattice, each of which was connected with its twelve nearest neighbors through very thin cylinders. Due to the charge neutrality of impinging gas molecules of the hyperthermal neutral beam, the spherical shape of polymer microspheres was almost maintained during the etching process. The Bragg reflection peaks were modulated by the etched volume of colloidal crystals. Finally, the inverse structures of such open structures were replicated by a simple room-temperature chemical vapor deposition and subsequently burning out polymer template spheres.

Bidirectional cavopulmonary shunt as a rescue procedure for right ventricular endomyocardial fibrosis.

The surgical treatment for patients with endomyocardial fibrosis consists of resection of endocardial fibrotic tissue and replacement or repair of atrioventricular valve. Even after endocardiectomy and valvular remodeling, some patients exhibit very poor hemodynamic profile because of myocardial failure due to long-standing restriction of ventricle or ventricles. Here, we report a case of endomyocardial fibrosis in right ventricle who underwent endocardiectomy and valvular replacement followed by bi-directional cavopulmonary shunt to compensate weaning failure from cardiopulmonary bypass. The long-term outcome and the indication of bi-directional cavopulmonary shunt has not been confirmed, although it was effective for saving the life of patients with low cardiac output and acute right ventricular failure.