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Carbon nanotubes (CNTs) were found to penetrate tomato seeds and affect their germination and growth rates. The germination was found to be dramatically higher for seeds that germinated on medium containing CNTs (10-40 mug/mL) compared to control. Analytical methods indicated that the CNTs are able to penetrate the thick seed coat and support water uptake inside seeds, a process which can affect seed germination and growth of tomato seedlings.
ACS Nano 2009 Oct 27
PMID:Carbon nanotubes are able to penetrate plant seed coat and dramatically affect seed germination and plant growth. 2290 Oct 75

The size and uniformity of magnetic nanoparticles developed from a group of uniform materials based on organic salts (GUMBOS) were controlled using an in situ ion exchange, water-in-oil (w/o) microemulsion preparation. Most of these nanoGUMBOS are in fact ionic liquids (i.e., melting points less than 100 degrees C), while others have melting points above the conventional 100 degrees C demarcation. Simple variations in the reagent concentrations following a w/o approach allowed us to smoothly and predictably vary nanoparticle dimensions across a significant size regime with excellent uniformity. Average sizes of GUMBOS particles ranging from 14 to 198 nm were achieved by manipulation of the reagent concentration, for example. Controllable formation of this new breed of nanoparticles is important for numerous potential applications and will open up interesting new opportunities in drug delivery, magnetic resonance imaging, and protein separations, among other areas.
ACS Nano 2009 Oct 27
PMID:Magnetic and nonmagnetic nanoparticles from a group of uniform materials based on organic salts. 1978 May 29

Three-dimensional nanoscale constructs are finding applications in many emerging fields, including energy generation and storage, advanced water and air purification, and filtration strategies, as well as photocatalytic and biochemical separation systems. Progress in these important technologies will benefit from improved understanding of fundamental principles underlying nanostructure integration and bottom-up growth processes. While previous work has identified hydrothermal synthesis conditions to produce nanoscale ZnO rods, sheets, and plates, strategies to systematically integrate these elements into more complex nano-architectures are not previously described. This article illustrates that amorphous nanoscale coatings formed by atomic layer deposition (ALD) are a viable means to modulate and screen the surface polarity of ZnO crystal faces and thereby regulate the growth morphology during successive hydrothermal nanocrystal synthesis. Using this new strategy, this work demonstrates direct integration and sequential assembly of nanocrystalline rods and sheets to produce complex three-dimensional geometric forms, where structure evolution is achieved by modifying the surface growth condition, keeping the hydrothermal growth chemistry unchanged. Therefore, rational planning of seed layer and feature spacing geometries may allow researchers to engineer, at the nanoscale, complex three-dimensional crystalline and semicrystalline constructs for a wide range of future applications.
ACS Nano 2009 Oct 27
PMID:Surface polarity shielding and hierarchical ZnO Nano-architectures produced using sequential hydrothermal crystal synthesis and thin film atomic layer deposition. 1978 32

A versatile synthetic method based on solvothermal technique has been developed for the fabrication of TiO(2) nanocrystals with different shapes such as rhombic, truncated rhombic, spherical, dog-bone, truncated and elongated rhombic, and bar. The central features of our approach are the use of water vapor as hydrolysis agent to accelerate the reaction and the use of both oleic acid and oleylamine as two distinct capping surfactants which have different binding strengths to control the growth of the TiO(2) nanoparticles. We also show that the presence of an appropriate amount of water vapor along with the desired oleic acid/oleylamine molar ratio plays a crucial role in controlling size and shape of TiO(2) nanocrystals.
ACS Nano 2009 Nov 24
PMID:Shape-controlled synthesis of highly crystalline titania nanocrystals. 1980 8

Paramagnetic ultrasmall gadolinium oxide (Gd(2)O(3)) nanoparticles with particle diameters (d) of approximately 1 nm were synthesized by using three kinds of Gd(III) ion precursors and by refluxing each of them in tripropylene glycol under an O(2) flow. A large longitudinal relaxivity (r(1)) of water proton of 9.9 s(-1) mM(-1) was estimated. As a result, high contrast in vivo T(1) MR images of the brain tumor of a rat were observed. This large r(1) is discussed in terms of the huge surface to volume ratio (S/V) of the ultrasmall gadolinium oxide nanoparticles coupled with the cooperative induction of surface Gd(III) ions for the longitudinal relaxation of a water proton. It is found from the d dependence of r(1) that the optimal range of d for the maximal r(1), which may be used as an advanced T(1) MRI contrast agent, is 1-2.5 nm.
ACS Nano 2009 Nov 24
PMID:Paramagnetic ultrasmall gadolinium oxide nanoparticles as advanced T1 MRI contrast agent: account for large longitudinal relaxivity, optimal particle diameter, and in vivo T1 MR images. 1983 89

Different crystal structures have been proposed as a basis for titanium oxide nanotubes. We have used atomistic simulation techniques to calculate the relative stability of nanotubes with these different crystal structures. Our approach is to use energy minimization, where the total interaction energy is calculated with interatomic potentials based on the Born model of solids. The results reveal nanotubes with the trititanate structure to be the most stable (at unit activity for water). Indeed, nanotubes with the trititanate structure were found to be thermodynamically more favorable than bulk trititanate for nanotube diameters greater than approximately 8 nm. However, the formation of cross-linking bonds between layers of the trititanate structure occurred frequently; this problem was eliminated by replacing two out of three Ti(4+) ions with Ti(3+) ions, although this resulted in a higher energy. Of the structures that do not contain hydrogen, chiral nanotubes made from (101) sheets of anatase are the lowest in energy, suggesting that this is the most likely structure for nanotubes synthesized at low water chemical potential. In general, the stability of the nanotubes increased as the nanotube diameter increased.
ACS Nano 2009 Nov 24
PMID:Energy minimization of single-walled titanium oxide nanotubes. 1984 36

This paper describes a process for the fabrication and positioning of nanowires (of Au, Pd, and conjugated polymers) embedded in thin epoxy slabs. The procedure has four steps: (i) coembedding a thin film of metal or conducting polymer with a thin film of nickel metal (Ni) in epoxy; (ii) sectioning the embedded structures into nanowires with an ultramicrotome ("nanoskiving"); (iii) floating the epoxy sections on a pool of water; and (iv) positioning the sections with an external magnet to a desired location ("magnetic mooring"). As the water evaporates, capillary interactions cause the sections to adhere to the substrate. Both the Ni and epoxy can be etched to generate free-standing metallic nanowires. The average translational deviation in the positioning of two nanowires with respect to each other is 16 +/- 13 mum, and the average angular deviation is 3 +/- 2 degrees . Successive depositions of nanowires yield the following structures of interest for electronic and photonic applications: electrically continuous junctions of two Au nanowires, two Au nanowires spanned by a poly(3-hexylthiophene) (P3HT) nanowire; single-crystalline Au nanowires that cross; crossbar arrays of Au nanowires; crossbar arrays of Au and Pd nanowires; and a 50 x 50 array of poly(benzimidazobenzophenanthroline ladder) (BBL) nanowires. Single-crystalline Au nanowires can be placed on glass wool fibers or on microfabricated polymeric waveguides, with which the nanowire can be addressed optically.
ACS Nano 2009 Oct 27
PMID:Integrated fabrication and magnetic positioning of metallic and polymeric nanowires embedded in thin epoxy slabs. 1985 84

The alpha-Fe(2)O(3) with various morphologies has been successfully synthesized via an ionic liquid-assisted hydrothermal synthetic method. The samples are characterized by X-ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscope (FE-SEM), transmission electron microscopy, and high-resolution transmission electron microscopy. The results indicate that the as-prepared samples are alpha-Fe(2)O(3) nanoparticles, mesoporous hollow microspheres, microcubes, and porous nanorods. The effects of the ionic liquid 1-n-butyl-3-methylimidazolium chloride ([bmim][Cl]) on the formation of the alpha-Fe(2)O(3) with various morphologies have been investigated systematically. The proposed formation mechanisms have also been investigated on the basis of a series of FE-SEM studies of the products obtained at different durations. Because of the unique porous structure, the potential application in water treatment of the alpha-Fe(2)O(3) porous nanorods was investigated. The UV-vis measurements suggest that the as-synthesized pure alpha-Fe(2)O(3) with various morphologies possess different optical properties depending on the shape and size of the samples. The magnetic hysteresis measurements indicate the interesting magnetic property evolution in the as-prepared alpha-Fe(2)O(3) samples, which is attributed to the superstructure or the shape anisotropy of the samples. This method is expected to be a useful technique for controlling the diverse shapes of crystalline inorganic materials for a variety of applications, such as sensors, gas and heavy metal ion adsorbents, catalytic fields, hydrogen and Li ion storage, and controlled drug delivery, etc.
ACS Nano 2009 Nov 24
PMID:Hematite (alpha-Fe2O3) with various morphologies: ionic liquid-assisted synthesis, formation mechanism, and properties. 1987 95

We demonstrate a novel chemical-free water-based technique to synthesize various forms of cuprous oxide nanostructures at room temperature. The self-assemblies of these nanostructures are formed by the anodic oxidation of Cu in deionized (DI) water. Direct growth of these nanostructures on SiO(2)/Si (100) substrate has been successfully achieved by tuning the bias voltage and the growth duration. A variety of nanostructures from one-dimensional nanowires to different complex two- and three-dimensional structures are successfully grown by this method. We show that the morphological evolution in the self-assembly of the structures strongly depends on the spatial electric field distribution on the substrate. Furthermore, the electrical devices made from these nanowire networks exhibit promising photon sensing characteristics under white light illumination and can be exploited for future applications in photodetection and photovoltaic studies at the nanoscale level.
ACS Nano 2009 Dec 22
PMID:Electric field directed self-assembly of cuprous oxide nanostructures for photon sensing. 1990 63

Honokiol (HK) can efficiently inhibit the growth of tumors. However, its clinical applications have been restricted by its extreme hydrophobicity. We hope to improve its water solubility by nanotechnology. And we wonder whether a novel honokiol nanoparticles-loaded thermosensitive poly(ethylene glycol)-poly(epsilon-caprolactone)-poly(ethylene glycol) (PEG-PCL-PEG, PECE) hydrogel (HK-hydrogel) could improve the therapeutic efficacy on malignant pleural effusion (MPE). To evaluate the therapeutic effects of HK-hydrogel on MPE, MPE-bearing mice were administered intrapleurally with HK-hydrogel, HK nanoparticles (HK-NP), blank hydrogel, or normal saline (NS) at days 4 and 11 after Lewis lung carcinoma (LLC) cells inoculation, respectively. Pleural tumor foci and survival time were observed, and antiangiogenesis of HK-hydrogel was determined by CD31. Histological analysis and assessment of apoptotic cells were also conducted in tumor tissues. HK-hydrogel reduced the number of pleural tumor foci, while prolonging the survival time of MPE-bearing mice, more effectively, as compared with control groups. In addition, HK-hydrogel successfully inhibited angiogenesis as assessed by CD31 (P < 0.05). Histological analysis of pleural tumors exhibited that HK-hydrogel led to the increased rate of apoptosis. This work is important for the further application of HK-hydrogel in the treatment of MPE.
ACS Nano 2009 Dec 22
PMID:Honokiol nanoparticles in thermosensitive hydrogel: therapeutic effects on malignant pleural effusion. 1992 11


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