Molecular doping of nucleic acids into light emitting crystals driven by multisite-intermolecular interaction.

We reveal the fundamental understanding of molecular doping of DNAs into organic semiconducting tris (8-hydroxyquinoline) aluminum (Alq3) crystals by varying types and numbers of purines and pyrimidines constituting DNA. Electrostatic, hydrogen bonding, and π-π stacking interactions between Alq3 and DNAs are the major factors affecting the molecular doping. Longer DNAs induce a higher degree of doping due to electrostatic interactions between phosphate backbone and Alq3. Among four bases, single thymine bases induce the multisite interactions of π-π stacking and hydrogen bonding with single Alq3, occurring within a probability of 4.37%. In contrast, single adenine bases form multisite interactions, within lower probability (1.93%), with two-neighboring Alq3. These multisite interactions facilitate the molecular doping into Alq3 particles compared to cytosines or guanines only forming π-π stacking. Thus, photoluminescence and optical waveguide phenomena of crystals were successfully tailored. This discovery should deepen our fundamental understanding of incorporating DNAs into organic semiconducting crystals.

Visual detection of odorant geraniol enabled by integration of a human olfactory receptor into polydiacetylene/lipid nano-assembly.

A new polydiacetylene lipid/human olfactory receptor nano-assembly was fabricated for the visual detection of an odorant for the first time. The assembly consisted of phospholipid-mixed polydiacetylenes (PDAs) and human olfactory receptors (hORs) in detergent micelles. To overcome the limitations of bioelectronic noses, hOR-embedded chromatic complexes (PDA/hORs) were developed, introducing PDAs that showed color and fluorescence transitions against various stimuli. The chromatic nanocomplexes reacted with target molecules, showing a fluorescence intensity increase in a dose-dependent manner and target selectivity among various odorants. As a result, a color transition of the assembly from blue to purple occurred, allowing the visual detection of the odorant geraniol. Through circular dichroism (CD) spectroscopy and a tryptophan fluorescence quenching method, the structural and functional properties of the hORs embedded in the complexes were confirmed. Based on this first work, future array devices, integrating multiple nano-assemblies, can be substantiated and utilized in environmental assessment and analysis of food quality.

Mercury ion-DNA specificity triggers a distinctive photoluminescence depression in organic semiconductor probes guided with a thymine-rich oligonucleotide sequence.

DNA strands have been recently found to play a role in crystallizing organic semiconductors as a substitute for conventional surfactants. Such DNA-guided organic semiconductor particles possessed the recognition ability to complementary target DNAs, resulting in "enhanced luminescence" due to the lesser degree of non-radiative dissipation. Apart from this, in this study we developed selective recognition of mercury ions by utilizing DNA probes having ion-specific thymine-rich motifs. Strikingly, the specific ion-DNA interaction triggered rather distinctive "depressed luminescence" emitting from the particles. The mercury ions were found to be present both at the surface and the inner regions, which were discovered to relate to the drastic morphological distortion of the particles as evidenced by elemental, electron microscopy, and confocal fluorescence microscopy analyses. This novel phenomenon discovered would expand the technological values of organic semiconductors conjugated with oligonucleotides toward a wider range of target-specific applications.

Capillary-Driven Sensor Fabrication of Polydiacetylene-on-Silica Plate in 30 Seconds: Facile Utilization of π-Monomers with C18- to C25-Long Alkyl Chain.

By utilizing the capillary-force-driven action, a novel polydiacetylene-based sensor on the porous silica plate was developed within 30 s for π-diacetylene monomers with variable chain lengths. This method enables one to utilize diacetylene monomers even with the shorter alkyl chain length of C18-C21, which has not been possible with conventional methods. The invented sensor platform employing shorter monomers was found to perform better, as was demonstrated for gaseous and aqueous analytes, i.e., ammonia gas and nucleic acids in aqueous phase. This new polydiacetylene platform opens up the development of quick and easy fabrication and the use of chemical and biochemical chips.

Bio-recognitive photonics of a DNA-guided organic semiconductor.

Incorporation of duplex DNA with higher molecular weights has attracted attention for a new opportunity towards a better organic light-emitting diode (OLED) capability. However, biological recognition by OLED materials is yet to be addressed. In this study, specific oligomeric DNA-DNA recognition is successfully achieved by tri (8-hydroxyquinoline) aluminium (Alq3), an organic semiconductor. Alq3 rods crystallized with guidance from single-strand DNA molecules show, strikingly, a unique distribution of the DNA molecules with a shape of an 'inverted' hourglass. The crystal's luminescent intensity is enhanced by 1.6-fold upon recognition of the perfect-matched target DNA sequence, but not in the case of a single-base mismatched one. The DNA-DNA recognition forming double-helix structure is identified to occur only in the rod's outer periphery. This study opens up new opportunities of Alq3, one of the most widely used OLED materials, enabling biological recognition.

Histologic changes of implanted gore bio-a in an experimental animal model.

Gore Bio-A has been reported to be an ideal synthetic bioabsorbable scaffold material for hernia repair. The purpose of this study was to determine the effectiveness of Gore Bio-A in soft tissue augmentation. Six New Zealand white rabbits were used in the study. Five subcutaneous pockets were created on the back of the rabbit, and 20 × 20 mm sized square shaped Gore Bio-A sheets, each 1.5 mm, 3 mm, 4.5 mm, 6 mm, and 7.5 mm in thickness, were implanted into each pocket (1 layer to 5 layers). To analyze the morphologic and histologic changes, the implants were harvested 1, 3, and 6 months after implantation. Following the gross analysis, absorption rate was accelerated with increased implant duration and decreased thickness. Histological analysis of the implants demonstrated progressive neovascularization, fibroblast infiltration, and neocollagenation over time. Six months after implantation, Gore Bio-A was almost absorbed and degenerated, not maintaining its volume. Based on this study, Gore Bio-A was revealed as a biocompatible material; however, it is not suitable for soft tissue augmentation because it is absorbed in the process of changing into soft tissue without maintaining its own volume. Therefore, this material is incomplete and needs more study to overcome this limitation.

Effect of Polygala tenuifolia root extract on cerebral ischemia and reperfusion.

In this study, the effects of Polygala tenuifolia root extract on brain ischemia/reperfusion injury in Mongolian gerbils were investigated. The gerbils were administered ethanol extract of P. tenuifolia and its four sub-fractions orally 2 hours prior to ischemia, and were subjected to a 20-minute no-flow cerebral ischemia in vivo. Thirty minutes and 72 hours after reperfusion, the brain was removed and the ATP, lactate and lipid peroxide levels were determined, and the neurons in the hippocampal CA1 subfield were examined. In the vehicle-treated ischemic gerbils, the brain ATP levels decreased significantly, but this decrease was prevented by pre-treatment with an n-butanol fraction of P. tenuifolia. In contrast, both the lactate content and lipid peroxidation levels were elevated in the vehicle-treated ischemic animals, but this elevation was inhibited by ethanol extract and n-butanol fraction of P. tenuifolia, respectively. Both the ethanol extract and n-butanol fraction of P. tenuifolia attenuated post-ischemic neuronal necrosis in the hippocampal CA1 subfield. Our findings suggest that both ethanol extract and n-butanol fraction of P. tenuifolia root can reduce brain damage during ischemia and reperfusion, and prevent lipid peroxidation and preserve the energy metabolism.

The efficacy of magnetic disks for the treatment of earlobe hypertrophic scar.

Ear piercing has been widely performed for various reasons, but it may cause hypertrophic scarring and its attendant cosmetic problems and/or subjective symptoms, such as pruritus or pain. Many treatment methods have been applied alone or in combination, including surgical excision, steroid injection, compression, radiation, topical silicone application, and so on. Although each modality or combined therapy has its advantages and disadvantages, in the authors' opinion, compressive therapy combined with surgical excision is the most effective method in many respects. However, the peculiar shape of the earlobe does not allow for easy compression. Thus, many compressive devices have been developed that are not wholly satisfactory in terms of effectiveness, appearance, size, or convenience. The authors describe a newly developed method for the treatment of hypertrophic scarring of the earlobe that uses magnetic disks. They treated 47 patients (91 auricles) with a hypertrophic scar on the earlobe that underwent compressive therapy using magnetic disks after surgical excision from April to December 2002. The use of magnetic disks proved effective, and they believe that it offers many advantages as a compressive device.