Narrow Results

AUSTRALIA — AIBN and Dow Launch Research Collaboration.

CHINA — US and China Ink Biofuels Cooperation Pact.

INDIA — Sanofi-Aventis Opens First Asian Pharmaceutical Development Center in India.

INDIA — India and France to Co-operate on Medical Research and Biotechnology.

INDONESIA — Bird Flu Resurfaces in Asia.

NEW ZEALAND — NZBio Launches Stem Cell Network.

NEW ZEALAND — Killer Hospital Superbug Infected 65 Patients.

SINGAPORE — MerLion Pharmaceuticals Wins Prestigious Pharmaceutical Industry Scrip Award.

SINGAPORE — ES Cell International Announces the Production of World's First Clinical-Grade Stem Cell Lines.

SINGAPORE — Association of Clinical Research Professionals Inaugurates Chapter in Singapore.

SOUTH KOREA — Disgraced South Korean Cloning Scientist Seeks Comeback.

SOUTH KOREA — Scientists Unlock Nanotube-Making Strain of Bacteria.

SOUTH KOREA — Samsung to Open Cancer Center.

In this short review, we report the facile fabrication of various interesting multi-component nanostructures including arrays of core-shell nanowires, multiwall nanotubes, segmented nanowires and multilayer stacked nanodisks, using anodized alumina membrane (AAM). We demonstrate that metallic (Cu, Ni and Au) and polymeric (PPV and PPy) one-dimensional (1D) arrays can be readily prepared by electrochemical deposition into the AAM. By optimizing the experimental design and conditions, we developed techniques to produce various multi-component nanostructures such as polymer/metal or metal/metal core-shell nanowires as well as nanotubes, with reasonably good control over both the length and the shell thickness of the nanostructures. Furthermore, we extend this method to make segmented nanowires as well as multilayer stacked nanodisks. Selective functionalization of the segmented nanowires resulted in end-on or side-on adhesion of nanowires during assembly. We illustrate the possibility of utilizing these 1D arrays to present patterns with luminescent and/or magnetic properties at this length scale.

Inorganic fullerene-like (IF) nanoparticles of MoS₂ were synthesized using gas-phase reaction starting from MoCl₅ and H₂S. The IF-MoS₂ nanoparticles are spherical and in some cases faceted with diameters in general ranging between 20 and 80 nm. The IF-MoS₂ nanoparticles have large hollow cores, filled in some cases with amorphous material. Various parameters have been investigated to understand the growth and formation of the IF-MoS₂ nanoparticles. The parameters that have been studied include flow rates of the various carrier gases, temperature at which the reaction was carried out, time of the reaction and heating of the precursor material. The best set of conditions wherein maximum yields of the IF-MoS₂ nanoparticles are obtained have been identified. Additionally, annealing the as-obtained samples or heating them in a mixture of H₂ along with H₂S improves the crystallinity and reduces the amorphous material filling in the core. Apart from the fullerene-like nanoparticles under certain experimental conditions nanotubes of MoS₂ have also been obtained nonetheless in small yields.

The effect of ultraviolet, visible and near-infrared irradiation on the yield and morphology of single crystalline C₆₀ fullerene nanowhiskers (FNWs) and nanotubes (FNTs) was investigated in an effort to produce large-scale quantities of FNWs and FNTs. These fullerene nanomaterials were synthesized by the liquid–liquid interfacial precipitation method using pyridine and isopropyl alcohol (IPA) as solvents. The C₆₀–pyridine solution was illuminated using different wavelengths for 24 h at ambient pressure and temperature before addition of IPA. High yields (30–38 mg/L) were obtained upon irradiation using wavelengths in the ultraviolet region in accordance with the increased photoabsorption signal of solid C₆₀ and C₆₀ dissolved in pyridine acquired by a UV-VIS-NIR spectrophotometer. However, elevated yields (21–27 mg/L) were also obtained in the 600–800 nm regions, where C₆₀ absorption is particularly weak. Such an enhanced yield of FNTs and FNWs is probably related to the reported rise in transient absorption of the triplet excited state of C₆₀ in the 740 nm region formed by the decay of the photoexcited singlet C₆₀ through intersystem crossing. The formation of photopolymerized fullerene nanofibers was also observed by Raman spectroscopy, it is attributed to ultraviolet and visible light irradiation. SEM and TEM observations suggest that preparation of FNWs and FNTs by irradiation using different wavelengths of light does not produce apparent morphological transformations on the surface of these fullerene materials.

Fe-decorated fullerene nanowhiskers were prepared by using the liquid–liquid interfacial precipitation method. The prepared nanowhiskers were characterized using scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM), X-ray diffraction (XRD) and Raman spectroscopy. Formation of both tubular and nontubular nanowhiskers was observed with fine dispersion of Fe ions. The XRD and Raman-spectroscopic studies showed the fcc crystalline nature and polymerization of the nanowhiskers, respectively. The results were compared with Ce- and Ni-incorporated fullerene nanowhiskers.

Ultra-thin (10–100 nm) conformal coatings of poly(ethyl 2-cyanoacrylate) and poly(p-xylylene) have been synthesized via vapor deposition in the confined nanochannels of anodized alumina membranes. Poly(ethyl 2-cyanoacrylate) nanotubes and coaxial poly(ethyl 2-cyanoacrylate)/poly(p-xylylene) nanotubes with precisely-controlled wall thickness were obtained after the removal of the inorganic anodized alumina membrane. Platinum nanoparticles have also been deposited in the coaxial nanotubes via supercritical carbon dioxide.

Time-dependent wet-processing of HiPCo nanotubes in ~ 0.5 M phosphoric acid and its effect on the structural, transport, infrared light absorption and photoconduction characteristics have been studied. Nanotubes were treated for nominal time intervals of 1, 2 and 3 h. The treatment is found to be a two-step process that initially results in the removal/partial replacement of most pre-existing C-O, O–H and CH_x groups with phosphorous oxy and carbonyl groups. According to T-dependent current–voltage measurements, the differential conductance, G of nanotube network varies with temperature as ~ T^a, with a exhibiting a slight increase as a result of the treatment, attributed to a slight increase in disorder and not doping effects. The nanotubes processed for three hours also show an order of magnitude improvement in photoconduction response time compared to that of untreated tubes, with growth/decay characteristic time constants approaching a sub-second range.

New types of core–shell nanoparticles are reported: Pb@GaS fullerene-like and nanotubular structures, achieved via the continuously high reactor temperatures and ultra-hot strong-gradient annealing environments created by highly concentrated sunlight. Structural and chemical characterizations suggest a formation mechanism where vaporized Pb condenses into nanoparticles that are stabilized as they become covered by molten GaS, the ensuing crystallization of which creates the outer layers. Hollow-core GaS fullerene-like nanoparticles and nanotubes were also observed among the products, demonstrating that a single solar procedure can generate a variety of core–shell and hollow nanostructures. The proposed formation mechanisms can account for their relative abundance and the characterization data.

Pure and Eu-doped (1.0, 3.0, 5.0wt.%) $\alpha$-Fe₂O₃ (PFO and EFO) nanotubes and nanowires have been successfully synthesized through the combination of electrospinning and calcination techniques. The structures, morphologies and chemical compositions of the as-obtained products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric and differential scanning calorimetry (TG-DSC) and energy dispersive spectrum (EDS), respectively. To demonstrate the superior gas sensing performance of the doped nanotubes, a contrastive gas sensing study between PFO (EFO) nanotubes and nanowires was performed. It turned out that Eu doping could magnify the impact of morphology on gas sensitivity. Specifically, at the optimum operating temperature of 240${}^{\circ }$C, the response value of PFO nanotubes to 100ppm acetone is slightly higher than that of nanowires (3.59/2.20). EFO (3.0wt.%) nanotubes have a response of 84.05, which is almost 2.7 times as high as that of nanowires (31.54). Moreover, they possess more rapid response/recovery time (11s and 36s, respectively) than nanowires (17s and 40s, respectively). The lowest detection limit for acetone is 0.1ppm and its response is 2.15. In addition, both of EFO nanotubes and nanowires sensors have a good linearity (0.1–500ppm) and favorable selectivity in acetone detection.

Carbon nanotubes (CNTs) have properties that promise an exciting role in nervous tissue repair. CNTs are strong, extremely light weight, biocompatible and electrically conductive. A relatively novel form of CNT material, multiple strands of CNTs spun into thread, accentuates the linear geometry of CNTs while retaining electrical conductivity. We propose that CNT thread, which is strong, pliable and readily manipulated, has the potential to support longitudinal growth of nerves after injury, in nervous system prostheses. Towards understanding how CNT materials support nervous tissue regeneration, we examined the in vitro interactions between CNT materials and neural stem cell-containing neurospheres, prepared from newborn mouse cortices. Intact neurospheres attached to pieces of as-grown arrays of CNTs, CNT "ribbon" material pulled from the arrays, and CNT thread. Stem cells differentiated into both neurons and glia under these conditions. Processes and cells aligned with the longitudinal axis of the CNT materials, both with and without coatings. For comparisons, dissociated neurosphere cells were plated on CNT thread, polypropylene surgical suture thread and commercial carbon fibers. Initial cell attachment (within seconds) and attachment at 24 h was greater on CNT thread than on the other fiber types. Stem cells on CNT threads differentiated into neurons and astrocytes over several days, on all fibers. The presence of serum greatly aided the health and spreading of both neurons and astrocytes. These findings demonstrate that CNT materials, in particular the thread form, are viable preparations for neural cell attachment, outgrowth and differentiation.

Nanotubes (NT) composed of the electrically active polymer poly (3,4-ethylenedioxythiophene) (PEDOT) have been used for photothermal ablation of both gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) bacteria. Since infrared absorption of PEDOT is dominated by bipolarons strongly coupled to phonons, we hypothesize that nonradiative decay of these states leads to heat generation. Photothermal death of bacteria by PEDOT NT was compared to single-wall carbon nanotubes (SWNT). Complete eradication of bacterial colonies incubated with 100 ug/ml of either PEDOT NT or SWNT occurred with a single exposure to 1064 nm light (3.8 W/cm²) for 60 s. PEDOT NT were also shown to elicit a mild antibacterial response upon incubation with bacteria and no infrared exposure. PEDOT NT have the same capacity for photothermal ablation of bacteria as compared to SWNT; therefore, they represent an exciting new class of polymer based nanoparticles for medically-relevant photothermal therapies.

Ordered arrays of Ni and Co nanowires and nanotubes, with diameters between 30 nm and 60 nm, were prepared by electrodeposition into nanoporous alumina templates. The study of the corresponding magnetization reversal processes was performed by analyzing the angular dependence of coercivity (H_c) and using a simple analytical model. The agreement between experimental and theoretical data shows that magnetization in nanowire arrays reverses by means of nucleation and propagation of a transverse domain wall, independently of the diameter. However, a critical diameter of ~ 50 nm was found in the case of nanotubes, above which a nonmonotonic angular dependent H_c was observed, evidencing a transition between vortex and transverse reversal modes.

Since the discovery of cisplatin, drugs based on platinum, have made a significant impact on the treatment of various cancers. The administration of platinum drugs is however accompanied by significant side effects. This chapter discusses the types of drug delivery systems that have been developed in order to enable the targeted delivery while maintaining controlled temporal supply of the drug. The sizes of carriers range from nanometer to micrometer sized particles. The most common types of drug carriers are micelles, liposomes, nanoparticles, and dendrimers, but also a few microspheres have been developed. Most striking aspect of the delivery of platinum drugs is the possibility of physical encapsulation but also the binding of the drug to the polymer carrier coordinate covalent bond. Since platinum drugs have typically two permanent and two leaving ligands, the polymer can be part of either ligand. As the leaving ligand, the platinum drug is released often as cisplatin. If the polymer provides the functionality for the permanent ligand, a new macromolecular drug has been formed. In addition to the attachment of pt(II) drugs, recent offorts are devoted to the conjugation via the Pt((IV) prodrug.

Nanotechnology has become a distinctive field of research, aimed to modernize the way scientists have addressed urgent needs and sophisticated problems, towards the achievement of unprecedented discoveries. Amidst the myriad of materials extensively used in the modern society, carbon-based systems seem to embody a significant role especially where endurance and strength are required: carbon nanoparticles, nanotubes, graphite, diamonds and fullerenes et al. In addition to the above advantages, this review also emphasizes some concerns on the carbonnanosystems and which are mainly attributable to the lack of an exhaustive characterization and to the potential hazardous effects deriving from their potential accumulation in the environment and inside the body.