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ABSTRACT: The identification of physicochemical factors that govern toxic effects of nanomaterials (NMs) is important for the safe design and synthesis of NMs. The release of metal cations from NMs in cell culture medium and the role of the metal cations in cytotoxicity are still under dispute. Here, we report that removal of NMs such as ZnO nanoparticles (NPs) by centrifugation, the procedure commonly used for the estimation of released ion concentration in nanotoxicology, was incomplete even at a relative centrifugal force of 150 000 × g. In this sense, the Zn concentration in supernatant measured by inductively coupled plasma-mass spectrometry cannot be regarded as the concentration of free Zn(2+) ions which were released from ZnO NPs in cell culture medium. This suggests the urgent need to develop relevant analytical techniques for nanotoxicology. The toxic contribution of released Zn(2+) ions to the A549 cell lines was estimated to be only about 10%. We conclude that the cytotoxicity associated with ZnO NPs is not a function of the Zn concentration, suggesting that other factors play an important role in the toxic effect of ZnO NPs.
Nanoscale 04/2013; · 5.91 Impact Factor
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Chemical Reviews 01/2013; · 40.20 Impact Factor
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ABSTRACT: We report on the synthesis of Fe(3)O(4) nanobelts with good magnetic properties and lithium storage performances by using a one-pot and template-free hydrothermal method with Na(2)CO(3) and FeCl(2) as the reactants. By controlling the amount of Na(2)CO(3), we obtained pure Fe(3)O(4) nanobelts with widths of 0.1-2 μm, thicknesses of about 10 nm and lengths of 20-30 μm, showing a high aspect ratio. XRD and SAED patterns of the obtained sample demonstrated that the Fe(3)O(4) nanobelts were well crystallized. Nitrogen adsorption/desorption measurements showed that Fe(3)O(4) nanobelts manifested a BET surface area of 25.04 m(2) g(-1). Further experiments demonstrated that the amount of Na(2)CO(3) played an important role in controlling both the morphologies and crystal structures of the products. The formation mechanism of Fe(3)O(4) nanobelts was also studied. More importantly, we found that the Fe(3)O(4) nanobelts showed magnetic properties with a magnetic saturation value of 77.0 emu g(-1) and lithium storage performances with a high initial discharge capacity of 1090 mAh g(-1) at a current rate of 500 mA g(-1), and a reversible capacity of 404 mAh g(-1) retained after 60 charge/discharge cycles. These results suggest that the Fe(3)O(4) nanobelts might be promising for magnetic and lithium battery applications.
Nanotechnology 09/2012; 23(39):395601. · 3.98 Impact Factor
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Lijian Zuo,
Xiaolian Hu,
Tao Ye,
Thomas R. Andersen,
Hanying Li,
Minmin Shi,
Mingsheng Xu,
Jun Ling,
Qiang Zheng,
Junting Xu,
Eva Bundgaard,
Frederik C. Krebs, Hongzheng Chen
The Journal of Physical Chemistry C 08/2012; 116(32):16893. · 4.80 Impact Factor
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ABSTRACT: Various semiconductors have been studied as photocatalysts for photocatalytic degradation of pollutants in aqueous solutions. As one of the promising visible-light-driven semiconductor photocatalysts, α-Fe(2)O(3) has advantages of low cost and stability. However, its application is inhibited by the poor separation of photogenerated electron-hole pair. In this work, hybrid structures were prepared to improve the performance of α-Fe(2)O(3). CdS nanoparticles were overgrown on the preformed single-crystalline α-Fe(2)O(3) nanorods by a simple and mild one-step wet-chemical method, resulting in α-Fe(2)O(3)/CdS cornlike nanocomposites. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Raman spectroscopy showed the α-Fe(2)O(3)/CdS core/shell heterostructure of the nanocomposite with high crystallinity. Furthermore, the cornlike nanocomposites exhibited superior photocatalytic performances under visible light irradiation over the pure α-Fe(2)O(3) nanorods and CdS nanoparticles. The photocatalytic activity of the composites is superior to the previously-reported pure α-Fe(2)O(3) nanomaterials, and the performance is comparable to both the commercial TiO(2) (P25) which is used under UV irradiation and the newly developed α-Fe(2)O(3)/SnO(2) photocatalyst under visible light irradiation. The enhanced performance is associated with the larger surface area of the cornlike structure, the crystalline nature of the materials and the synergy in light absorption and charge separation between α-Fe(2)O(3) and CdS. As such, our α-Fe(2)O(3)/CdS cornlike nanocomposites may be promising to be used as visible-light-driven high-performance photocatalyst.
ACS Applied Materials & Interfaces 08/2012; 4(9):4800-6. · 4.53 Impact Factor
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ABSTRACT: High-performance hybrid solar cells (HSCs) based on P3HT : CdSe QD blends are achieved through post-deposition ligand exchange by n-butanethiol (n-BT) with a high power conversion efficiency of 3.09%. The mechanism by which n-BT modifies the surface structures of CdSe QDs and thus improves the HSCs performance is investigated.
Physical Chemistry Chemical Physics 08/2012; 14(35):12094-8. · 3.57 Impact Factor
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ABSTRACT: The components and their concentration ratio of surfactant mixture in aqueous solution of gelatin and sodium carboxymethylcellulose
(NaCMC) are very important during the preparation of stable microcapsules for electrophoretic display. In this work, hydrocarbon/fluorocarbon
composite surfactant was introduced for the first time into the capsule wall to improve the chemical resistance and barrier
property of the microcapsules. By investigating surface tension and zeta potential of NaCMC with the mixture of sodium dodecyl
sulfate (SDS)/perfluoro-nonene oxy benzene sulfonate (OBS), we found that both the presence of hydrophobic interaction and
the hydrogen bonding between NaCMC and SDS/OBS enhanced the adsorption of NaCMC at the oil/water interface and thus facilitated
the formation of capsule wall. The morphology, particle size, surface free energy and thermal stability of the obtained microcapsules
were characterized. The results showed that optically transparent microcapsules with uniform size, smooth surface and compact
wall can be obtained by adjusting the pH value of the reaction system and the concentration ratio of SDS/OBS. Based on the
prepared microcapsules, a matrix display prototype operated at 9 V direct current in static driven mode was fabricated.
Keywordsmicrocapsules–compact wall–sodium carboxymethylcellulose–sodium dodecyl sulfate/perfluoro-nonene oxy benzene sulfonate composite surfactant–electrophoretic display
Science China-Chemistry 05/2012; 54(2):385-391. · 1.02 Impact Factor
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ABSTRACT: The performance of electrophoretic displays is strongly dependent on the stability of the electrophoretic suspension in the
device. In this manuscript, to obtain the stable electrophoretic suspension, the titanium dioxide grafted with poly [N-(p-vinyl benzyl) phthalimide] (TiO2-g-PVBP) composite particles were prepared via radical polymerization. The obtained TiO2-g-PVBP composite particles were fully characterized. The results showed that PVBP was grafted onto TiO2 surface by chemical bonding. The composite particles with the effective diameter of 300nm can monodisperse stably in tetrachloroethylene
due to the long-chain polymer PVBP, which can provide each TiO2 particle with steric stabilization. The zeta potential and electrophoretic mobility of the composite particles were 30.3mV
and 4.69 × 10−6cm2/Vs, respectively, without charge control agent. With the stable electrophoretic suspension containing the prepared composite
particles, the matrix electrophoretic display prototype with good performance operated at 9 V was demonstrated.
KeywordsTitanium dioxide–Suspension stability–Grafting polymer–Electrophoretic displays
Colloid and Polymer Science 04/2012; 289(4):401-407. · 2.33 Impact Factor
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ABSTRACT: Information on how cells interface with nanomaterials in biological environments has important implications for the practice of nanomedicine and safety consideration of nanomaterials. However, our current understanding of nanobiological interactions is still very limited. Here, we report the direct observation of nanomaterial bio-complex formation (other than protein corona) from nanomaterials dispersed in biologically relevant solutions. We observed highly selective binding of the components of cell culture medium and phosphate buffered saline to ZnO and CuO nanoparticles, independent of protein molecules. Our discoveries may provide new insights into the understanding of how cells interact with nanomaterials.
Scientific Reports 01/2012; 2:406.
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ABSTRACT: In this study, gold nanoparticles (GNP) were stabilized for the first time as dimers by a conducting polymer (CP). The morphology of kissing particles was examined by high-resolution transmission electronic microscopy (HRTEM). The broad-band localized surface plasmon resonance (LSPR) tunable by solvent variation and molecular binding was demonstrated by UV-vis measurement. The sensitivity of the longitudinal LSPR to the surrounding media or the binding of a biomolecule was 6 times higher than that of the transversal LSPR. A homogeneous bioassay was directly developed from the highly stable GNP-CP dimers with LSPR as prober, and protein sensing with detection limit well below 100 ng/mL was achieved.
Langmuir 06/2011; 27(12):7884-91. · 4.19 Impact Factor
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ABSTRACT: Water-soluble, monodispersed, and bluish green-emitting Au(10) nanoclusters were synthesized through a simple reaction, in which histidine served as both a reducing agent and a protecting ligand. UV-visible absorption, photoluminescence, electrospray ionization (ESI) mass spectrometry, and X-ray photoelectron spectroscopy (XPS) were carried out to demonstrate the chemical composition and optical properties of the Au(10) clusters. The mechanism of this proposed reaction was explored and the reducing ability of histidine was proved from its imidazole group. Finally, the fluorescence of Au NCs at different reaction times, pH value, and temperature was measured in situ. Then a synthetic strategy was proposed for gold nanoclusters with a defined chemical composition, and the resulting Au(10) clusters stabilized by histidine are biocompatible with bioorganisms, showing a great potential for applications such as biological labeling and biosensors.
Nanoscale 06/2011; 3(6):2596-601. · 5.91 Impact Factor
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ABSTRACT: We report that few-layer hexagonal boron nitride (h-BN) nanosheets can be produced by using a surface segregation method. The formation of h-BN sheets is via an intermediate boron-nitrogen buffer layer. Our results suggest that surface segregation of boron and nitrogen from a solid source is an alternative approach to tailoring synthesis of h-BN sheets for potential applications such as in graphene electronics.
Nanoscale 05/2011; 3(7):2854-8. · 5.91 Impact Factor
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ABSTRACT: Two diketo-pyrrolo-pyrrole-based donor–acceptor copolymers, PCPDT–PDPP and PDTP–PDPP, were synthesized and applied as p-type component for bulk heterojunction solar cells. Using a facile molecular engineering of the main chain linking bridge, we have successfully tuned the band gap of the materials from low to medium level, which results in an improved balance between the device open circuit voltage and short circuit current. The power conversion efficiencies of the polymer/PC70BM combinations achieve 2.03% (PCPDT–PDPP) and 1.32% (PDTP–PDPP) without any interface engineering or post-treatment. A totally different composition-dependent photovoltaic behavior was also discovered for each of the two materials, although they share similar donor–acceptor (D–A) structure. Morphological and photophysical studies reveal a phase structure dominated, light harvesting subordinated mechanism, in which some nonkernel molecular level factors, such as the branch chain density and the molecular weight, are found to play important roles.
05/2011;
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Advanced Materials 03/2011; 23(16):1903 - 1908. · 13.88 Impact Factor
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ABSTRACT: We use gold nanospheres (Au NSs) to improve the performance of polymer organic solar cells. Au NSs with a diameter of about 5 nm or 15 nm were doped into the buffer layer of organic solar cells. We attribute the efficiency improvement to the size-dependent localized surface plasmon resonance (LSPR) effect of Au NSs, which can enhance the light harvest ability of active layer around the Au NSs, and increase the probability of the exciton generation and dissociation. Our results show that solar cells doped with 15 nm-diameter Au NSs exhibit significant improvement of the efficiency (from 1.99% to 2.36%), while solar cells doped with only 5 nm-diameter Au NSs did not give obvious improvement of the performance.
Applied Energy 03/2011; 88(3):848-852. · 5.11 Impact Factor
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Advanced Materials 03/2011; 23(16):1903-8. · 13.88 Impact Factor
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ABSTRACT: We investigated fluorescence quenching and enhancement near gold nanoparticles (GNP) of various sizes using fluorescently labeled hairpin DNA probes of different lengths. A closed hairpin caused intimate contact between the fluorophore and the gold, resulting in an efficient energy transfer (quenching). Upon hybridization with complementary DNA, the DNA probes were stretched yielding a strong increase in fluorescence signal. By carefully quantifying the amount of bound fluorescent probes and the GNP concentrations, we were able to determine the quenching and enhancement efficiencies. We also studied the size and distance dependence theoretically, using both FDTD simulations and the Gersten-Nitzan model and obtained a good agreement between experiments and theory. On the basis of experimental and theoretical studies, we report over 96.8% quenching efficiency for all particle sizes tested and a maximal signal increase of 1.23 after DNA hybridization. The described results also demonstrate the potential of gold nanoparticles for label free DNA sensing.
Analytical Chemistry 02/2011; 83(4):1307-14. · 5.86 Impact Factor
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ABSTRACT: To increase the open circuit voltage (V(OC)) of polymer solar cells (PSCs) based on polythiophene, two new ester group functionalized polythiophene derivatives, PCTDT and PCTBDT, were designed and synthesized via alternating copolymerization of thiophene-3-carboxylate (CT) with the 2,2'-bithiophene (DT) and benzodithiophene (BDT) units, respectively. The resulting copolymers exhibited broad and strong absorptions in the visible region, which was similar to that of the commonly used poly(3-hexylthiophene) (P3HT). Through cyclic voltammetry measurements, it was found that both copolymers showed lower HOMO energy levels (-5.27 eV for PCTDT and -5.36 eV for PCTBDT) than that of P3HT (-5.03 eV), indicating that the HOMO energy level could be efficiently reduced by introducing the ester group into the polymer side chain. Photovoltaic properties of the copolymers blended with [6,6]-phenyl-C(61)-butyric acid methyl ester (PCBM) as electron acceptor were investigated. The obtained two devices possessed both relatively large short circuit current (I(SC)) and higher V(OC) than that of P3HT:PCBM blend. For PCTBDT:PCBM blend, a power conversion efficiency (PCE) up to 2.32%, an I(SC) of 6.94 mA · cm(-2), and a V(OC) of 0.80 V were observed while PCTDT:PCBM system demonstrated a PCE of 1.75% with a V(OC) of 0.68 V.
Macromolecular Rapid Communications 01/2011; 32(6):506 - 511. · 4.60 Impact Factor
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ABSTRACT: Two hybrid bilayer ultraviolet photodetectors have been fabricated by spin-coating with poly(9,9-dihexylfluorene) (PFH) and ZnO nanoparticles as electron donor and acceptor, respectively. The device structure is inverted for device A: indium tin oxide (ITO)/ZnO/PFH/Au, while for device B a normal structure is applied: ITO/PFH/ZnO/Al. Both devices exhibit obvious photoresponse with a photo-to-dark current ratio of 3–4 orders of magnitude under UV radiation of 1 mW cm−2 at 365 nm through the ITO electrode. Under reverse bias, the photoresponse of device A exhibits severe persistent photoconduction. However, this is efficiently avoided in device B due to the presence of sufficient oxygen to capture the free electrons in ZnO. The study shown here may provide a useful guideline to achieve low-cost hybrid UV detectors with rapid response.
Journal of Physics D Applied Physics 10/2010; 43(42):425101. · 2.54 Impact Factor
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ABSTRACT: A nanocomposite material (Si@MWCNT) with a core/sheath heterostructure consisting of silicon nanoparticles (Si-NPs) covalently bonded onto a multi-walled carbon nanotube (MWCNT) is used as a new material for solar cells. The photovoltaic response of a poly (3-hexylthiophene) (P3HT)/Si@MWCNT hybrid film is studied by I–V measurements under simulated one-sun AM 1.5 illumination (100 mW cm − 2). In comparison with simple P3HT/Si-NPs and P3HT/MWCNT devices, the power conversion efficiency of the (P3HT)/Si@MWCNT nano-hybrid device is enhanced by 3 and 20 times, respectively. Photo-physical and energy diagram investigations suggest that the improved device performance is attributed to the combination of efficient charge generation by the P3HT/Si-NPs bulk heterojunction and efficient charge collection as a result of MWCNT template directed carrier transport.
Nanotechnology 07/2010; 21(34):345201. · 3.98 Impact Factor
