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ABSTRACT: Self-assembly of ZnO porous nanosheets with novel parallelogram morphology and high specific surface area is achieved by a one-pot alkalization reaction. The growth mechanism relies on the dual roles of the precursor: providing the building blocks and the assembling template concurrently. This porous structure with active surface defects serves as a high-performance semiconductor substrate for surface-enhanced Raman scattering (SERS).
Small 04/2013; · 8.35 Impact Factor
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ABSTRACT: Inspired by Pearson's hard and soft acid-base (HSAB) principle, uniform amorphous Ni(OH)2 nanoboxes with intact shell structures and various sizes are quickly fabricated by deliberately selecting S2 O3 (2-) as the coordinating etchant toward Cu2 O templates and optimizing the reaction conditions. It is found that not only the solvent system but also the employing of a surfactant is vital for the fabrication of the nanoboxes. Ni(OH)2 nanoboxes, as an example, demonstrate an improved electrochemical sensing ability for glucose, which might be due to their amorphous and hollow structural features.
Small 04/2013; · 8.35 Impact Factor
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ABSTRACT: Surface-enhanced Raman scattering (SERS) spectra of 4-mercaptobenzoic acid (4-MBA) have been investigated on the surface of Cu(2)O nanospheres. The SERS signals were believed to originate from the static chemical enhancement, resonant chemical enhancement and electromagnetic enhancement. The coupling between the adsorbates and the semiconductor, evidenced by the shift in absorption spectrum of modified Cu(2)O and the enhancement of non-totally symmetric modes of the 4-MBA and 4-mercaptopyridine (4-MPY) molecules, were invoked to explain the experimental results. Furthermore, simulations were employed to investigate the nature of the enhancement mechanisms operative between the molecules and the semiconductor. Density functional theory (DFT) calculations suggested a charge transfer (CT) transition process between the molecules and the Cu(2)O nanospheres. Three-dimensional finite-difference time domain (3D-FDTD) simulations were conducted to map out the electromagnetic field around the Cu(2)O nanospheres. The experimental and simulation results have revealed the promise of the Cu(2)O nanospheres as a good SERS substrate and the prospect of using the SERS substrate as a valuable tool for in situ investigation and assay of the adsorption behavior on semiconductor surfaces.
Nanoscale 02/2013; · 5.91 Impact Factor
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ABSTRACT: Multifunctional integration is an inherent characteristic for biological materials with multiscale structures. Learning from nature is an effective approach for scientists and engineers to construct multifunctional materials. In nature, mollusks (abalone), mussels, and the lotus have evolved different and optimized solutions to survive. Here, bio-inspired multifunctional graphene composite paper was fabricated in situ through the fusion of the different biological solutions from nacre (brick-and-mortar structure), mussel adhesive protein (adhesive property and reducing character), and the lotus leaf (self-cleaning effect). Owing to the special properties (self-polymerization, reduction, and adhesion), dopamine could be simultaneously used as a reducing agent for graphene oxide and as an adhesive, similar to the mortar in nacre, to crosslink the adjacent graphene. The resultant nacre-like graphene paper exhibited stable superhydrophobicity, self-cleaning, anti-corrosion, and remarkable mechanical properties underwater.
Nanoscale 02/2013; · 5.91 Impact Factor
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ABSTRACT: We report the microstructure, gas-sensing properties of the ordered mesoporous Co3O4 prepared by modified KIT-6 template method. Highly ordered mesoporous nanostructures of the as-prepared products have been characterized by X-ray diffraction (XRD), extended X-ray absorption fine structure (EXAFS), high-resolution transmission electron microscopy (HRTEM) and N2 adsorption/desorption analysis. We find that the ordered mesoporous Co3O4 enables a significant improvement of sensor response and selectivity to ethanol, which demonstrates the potential use of the ordered mesoporous Co3O4 as alcohol gas-sensing material. Through the analysis of microstructure including HRTEM and N2 adsorption/desorption, the sensing properties for the ordered mesoporous Co3O4 can be attributed qualitatively to its large specific surface area and porous morphology. Moreover, the results of EXAFS illustrate that the disorder degree and unsaturated bond of the ordered mesoporous Co3O4 increase, which agree well with the results observed in gas sensors. This makes the nanostructured ordered mesoporous Co3O4 a promising sensor material for detecting the alcohol gas.
Journal of Nanoscience and Nanotechnology 02/2013; 13(2):864-8. · 1.56 Impact Factor
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ABSTRACT: Oncoprotein platelet derived growth factor-BB (PDGF-BB) is one of the most critical growth factors that regulates tumor growth and division. In this work, a highly sensitive and selective fluorescence resonance energy transfer (FRET) aptasensor for PDGF-BB detection based on the assembly of dye-labeled aptamer and graphene oxide (GO) is developed for the first time. Due to the non-covalent assembly between aptamer and GO, fluorescence quenching of the dye takes place because of FRET. In the presence of PDGF-BB, the binding between aptamer and PDGF-BB will disturb the interaction between aptamer and GO, and release the dye-labeled aptamer from the GO surface, resulting in restoration of the fluorophore fluorescence. Because of the high fluorescence quenching efficiency, unique structure, and electronic properties of GO, the GO aptasensor exhibits extraordinarily high sensitivity. We also demonstrate that two highly related molecular variants of PDGF (AA, AB) can be distinguished from PDGF-BB, which indicates the aptasensor has excellent selectivity. Such an aptasensor opens a rapid, selective and sensitive route for the detection of PDGF-BB and provides a promising strategy for other cancer-related proteins detections.
The Analyst 01/2013; · 4.23 Impact Factor
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ABSTRACT: As the properties of nanomaterials are strongly dependent on their size, shape and nanostructures, probing the relations between macro-properties and nanostructures is challenging for nanoscientists. Herein, we deliberately chose three types of Ni(OH)(2) with hexagonal, truncated trigonal, and trigonal hourglass-like nanostructures, respectively, as the electrode modifier to demonstrate the correlation between the nanostructures and their electrocatalytic performance towards L-histidine. It was found that the hexagonal hourglass-like Ni(OH)(2) sample had the best electrocatalytic activity, which can be understood by a cooperative mechanism: on one hand, the hexagonal sample possesses the largest specific surface area and the tidiest nanostructure, resulting in the most orderly packing on the electrode surface; on the other hand, its internal structure with the most stacking faults would generate a lot of unstable protons, leading to an enhanced electronic conductivity. The findings are important because they provide a clue for materials design and engineering to meet a specific requirement for electrocatalysis of L-histidine, possibly even for other biomolecules. In addition, the hexagonal Ni(OH)(2) -based biosensor shows excellent sensitivity and selectivity in the determination of L-histidine and offers a promising feature for the analytical application in real biological samples.
Chemistry 12/2012; · 5.93 Impact Factor
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ABSTRACT: In this paper, LiFePO(4)/C microspheres consisting of closely packed nanosheets have been synthesized via a simple solvothermal method and a subsequent carbon coating procedure. In order to clarify the microstructure of the product, the as-prepared composite has been characterized by various techniques, such as powder x-ray diffraction, scanning electron microscopy, energy dispersive spectrum, Raman spectroscopy and high-resolution transmission microscopy. Results show that the LiFePO(4)/C microspheres are uniform with a particle size of 8-10 μm. The microspheres are composed of densely compacted nanosheets with a thickness of 20-30 nm. The gaps between the nanosheets are estimated to be 10-50 nm; a carbon layer with a thickness of ∼4 nm is coated on the surface of the LiFePO(4) spheres. The tap density of the LiFePO(4)/C composite reaches up to 1.5 g cm(-3). As cathode material for Li-ion batteries, the composite exhibits a high capacity: 155 mAh g(-1), 144 mAh g(-1), 129 mAh g(-1), and 104 mAh g(-1) at 0.1 C, 1 C, 5 C and 10 C, respectively. Furthermore, the material also shows good cycling stability at both low and high current rates. The unique nanostructure of the material promises its excellent electrochemical properties as a cathode material for lithium batteries.
Nanotechnology 11/2012; 23(47):475401. · 3.98 Impact Factor
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ABSTRACT: In this work, we described a signal-on architecture for electrochemical aptasensors that is applicable to a wide range of aptamers. Herein, we use thrombin as the model sensing target. The signal-on aptasensor is composed of multiple ion channels embedded within a polymeric membrane, with the anti-thrombin aptamers chemically modified onto the inner walls of each ion channel working as the sensing element. As the thrombin concentration increased, [Ru(NH3)6]3+ which was electrostatically absorbed onto the negatively charged phosphate backbones of aptamers beforehand, was displaced and pushed into the ion channels from the inner walls, leading to an increase in the current of redox cations at the working electrode surface. Compared with the traditional two-electrode design using a single ion channel sensing system, our ion channel sensing system is applied multiple times within an ordinary three-electrode system, providing such advantages as a high signal-to-noise ratio and suitability for a wide variety of redox species. The results indicate that multiple ion channel sensing provides improvements of orders of magnitude in signal sensitivity. In particular, this signal-on architecture avoids the problems of limited signal gain and "false positives". Moreover, the proposed aptasensor is simple, highly selective, stable and applicable to real samples.
Analytical Chemistry 11/2012; · 5.86 Impact Factor
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ABSTRACT: A flexible free-standing graphene/SnO2 nanocomposites paper (GSP) was prepared by coupling a simple filtration method and a thermal reduction together for the first time. Compared with the pure SnO2 nanoparticles, the GSP exhibited a better cycling stability, because the graphene with high mechanical strength and elasticity can work as a buffer to prevent the volume expansion and contraction of SnO2 nanoparticles during Li+ insertion/extraction process. Meanwhile, compared with single graphene paper, the GSP showed a higher capacity because of the hybridizing with higher capacity SnO2 nanoparticles. The excellent electrochemical performance of the GSP as an anode material in Li-ion battery was obtained. The as-prepared GSP shows a great potential for flexible Li-ion batteries.
ACS Applied Materials & Interfaces 10/2012; · 4.53 Impact Factor
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ABSTRACT: Cutting edge: A Cu(2) O jagged polyhedron, with numerous {110} edges and {111} corners, has been developed through a top-down selective oxidative etching process at the expense of the original {111} facet. The as-prepared nanocrystals exhibited higher photocatalytic activities for the degradation of methylene orange, which may be primarily ascribed to the increased edges and corners.
Chemistry 09/2012; 18(45):14261-6. · 5.93 Impact Factor
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ABSTRACT: In recent years, the synergistic effects of Au-based hybrids have generated enormous scientific interest. The hybrids of Au and Co are expected to exhibit attractive properties. In this paper, we report the successful fabrication of the nanohybrids between bulk-immiscible Au and Co with chain-like structures via a mild solution method. Elemental mapping, XRD and EXAFS data reveal that the as-prepared AuCo nanohybrids might be of cluster mixed configuration. A sequential redox and imperfection-promoted aggregation/diffusion process is proposed to elucidate the formation mechanism of the nanohybrids. The as-prepared products exhibit a temperature-independent saturation magnetization with the magnetic moment of Co as high as ∼2.95 μ(B) for each Co atom at 300 K, much higher than the bulk value (∼1.7 μ(B) for each Co atom) and approaching the theoretical value of an atomic Co (∼3.0 μ(B) for each Co atom).
ACS Applied Materials & Interfaces 09/2012; 4(10):5643-9. · 4.53 Impact Factor
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ABSTRACT: Highly reproducible surface-enhanced Raman scattering (SERS) spectra are obtained on the surface of SnO(2) octahedral nanoparticles. The spot-to-spot SERS signals show a relative standard deviation (RSD) consistently below 20 % in the intensity of the main Raman peaks of 4-mercaptobenzoic acid (4-MBA) and 4-nitrobenzenethiol (4-NBT), indicating good spatial uniformity and reproducibility. The SERS signals are believed to mainly originate from a charge-transfer (CT) mechanism. Time-dependent density functional theory (TD-DFT) is used to simulate the SERS spectrum and interpret the chemical enhancement mechanism in the experiment. The research extends the application of SERS and also establishes a new uniform SERS substrate.
ChemPhysChem 09/2012; · 3.41 Impact Factor
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ABSTRACT: A novel, effective and simple surface-enhanced Raman scattering (SERS) nanosensor for selectively and sensitively detecting heavy metal ions in aqueous solution has been developed in the form of 2-mercaptoisonicotinic acid (2MNA)-modified gold nanoparticles (AuNPs). Multiple heavy metal ions can be identified and quantified by using relative peak intensity ratios of selected vibrational bands in the SERS spectra of 2MNA. Especially, concentration of Hg(2+) and Pb(2+) ions are determined by comparing the intensity ratios of the bands 1160/1230cm(-1) for Hg(2+) and 861/815cm(-1) (or 815/1392cm(-1)) for Pb(2+), with detection limits of 3.4×10(-8) and 1.0×10(-7)M, respectively. 2MNA-AuNPs sensors show a high selectivity for Hg(2+) without masking reagent, and they can also be highly selective for Pb(2+) when using sodium thiosulphate and l-cysteine as masking reagents. These results demonstrate that these 2MNA-AuNPs nanosensors are promising candidates for in situ heavy metal ions detection and quantification, maybe even inside living cells.
Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 08/2012; 97:1007-12. · 2.10 Impact Factor
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ABSTRACT: The recent development in the nanotechnology has paved the way for a large number of alloyed nanomaterials and devices of desirable properties which have useful functions for electrochemical sensor and biosensor applications. In this paper, bimetallic AuPt nanochains were synthesized through a mild chemical method, with which anti-horseradish peroxidase-conjugated anti-carcinoembryonic antigen (HRP-anti-CEA-NCAuPt) was developed for electrochemical detection of carcinoembryonic antigen (CEA) in a sandwich-type immunoassay format. The alloyed nanocrystals exhibit not only sound signal amplification effect of Au nanoparticles, but also further new combination of interfacial, electrical and structural properties arising from the disparate AuPt components. As a result, the electrochemical signal was significantly amplified by using the HRP-anti-CEA-NCAuPt as tracer and hydrogen peroxide as enzyme substrate. The linear range of the developed immunosensor is 0.01-200ng/mL and the detection limit is 0.11pg/mL of CEA, which makes the biometallic nanochains promising candidates for the next-generation sandwich-type electrochemical immunoassays.
Biosensors & bioelectronics 07/2012; 39(1):226-30. · 5.43 Impact Factor
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ABSTRACT: Hyperactivation of nuclear factor-κB (NF-κB) is associated with various types of tumors. This study investigated the susceptibility of the rs4648068 A/G genotype in the intron region of NFKB1 to gastric cancer and the association of this polymorphism with clinicopathologic variables in gastric cancer patients.
A hospital-based case-control study of 248 gastric cancer patients and 192 control individuals was conducted in Fudan University Shanghai Cancer Center (Shanghai, China). Single nucleotide polymorphism (SNP) rs4648068 genotype in NFKB1 from blood samples of a total of 440 people was analyzed by polymerase chain reaction-based genotyping.
The frequencies of the AA, AG, and GG genotypes of the rs4648068 polymorphism were 31.5%, 47.2%, and 21.3% in the gastric cancer patients and 29.7%, 59.9%, and 10.4% in the control individuals, respectively. We found that the GG genotype was associated with a significantly increased risk of gastric cancer (P = 0.042). Furthermore, among the gastric cancer cases, the rs4648068 GG genotype was associated with high clinical stage (AOR = 2.27, 95% CI: 1.11- 4.66), lymph node involvement (AOR = 2.90, 95% CI = 1.40- 6.03) and serosa invasion (AOR = 2.78, 95% CI = 1.34- 5.75). However, rs4648068 genotypes were not associated with tumor differentiation in gastric cancer patients.
Homozygous rs4648068 GG was associated with an increased risk of gastric cancer, especially for the lymph node status and serosa invasion in Han Chinese population.
BMC Gastroenterology 07/2012; 12:87. · 2.42 Impact Factor
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ABSTRACT: Polyhedral AgBr nanocrystals, evolved from cubes through truncated cubes and finally to high-symmetry octahedra, which corresponds to a progressive shrinkage of exposed {100} facets and enlargement of exposed {111} facets, are prepared by facile precipitation reactions. The as- prepared AgBr nanocrystals exhibit facet-dependent catalytic properties, with the {111}-dominated octahedra showing the highest photocatalytic activities.
Small 07/2012; 8(18):2802-6. · 8.35 Impact Factor
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ABSTRACT: We have developed a surface-enhanced Raman scattering (SERS) nanosensor firstly for Ag ions and Ag nanoparticles detection based on 2-mercaptoisonicotinic acid (2MNA)-functionalized Au nanoparticles. Ag(+) can coordinate with 2MNA resutling in a variation of its SERS spectrum, which is used as a criterion to determine Ag(+) in a solution. This sensor exhibits a detection limit no more than 25 nM and has a high selectivity against other metal ions. More importantly, it can be directly applied in real sample detection.
The Analyst 06/2012; 137(17):3925-8. · 4.23 Impact Factor
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ABSTRACT: BACKGROUND: The potentially functional polymorphism, rs909253 (+252 G>A), in the intron region of the LT-α (TNF-β) gene has been implicated in the risk of gastric cancer (GC) in some individually published studies, but others have shown inconsistent and inconclusive results. METHODS: We conducted a meta-analysis to assess the association between the lymphotoxin-α gene (LTA)+252 (G>A) polymorphism and gastric cancer susceptibility. RESULTS: We demonstrate that there were no significant associations in single-locus analysis between the polymorphism of LTA and gastric cancer risk in all subjects; however, when studies were stratified by ethnicity, these polymorphisms of LTA were found to be associated with a significant cancer risk in different genetic models in an Asian population (heterozygote [GA genotype] comparison: odds ratio [OR]=1.29, 95% confidence interval [CI]: 1.01-1.65, P=0.038) in which the risk in the subjects was more than 70% (12 studies with 2074 cases and 3690 controls). Moreover, the susceptibility to gastric carcinogenesis has a substantial influence on the population-attributable risk by modulating the effects of environmental risk factors such as Helicobacter pylori infection (OR=1.77, 95%CI: 1.05-2.99, P=0.032). CONCLUSIONS: The present meta-analysis results suggest that the LTA rs909253 GA genotype is a possible risk factor for developing gastric cancer in the Asian population, especially those with H. pylori infection.
Cancer epidemiology. 06/2012;
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ABSTRACT: We have designed a large-scale three-dimensional (3D) hybrid nanostructure as surface-enhanced Raman scattering (SERS) sensor by decorating silver nanoparticles on TiO(2) nanorods scaffold (Ag/TiO(2)). Taking p-mercaptobenzoic acid (PMBA) as the probe molecule, the SERS signals collected by point-to-point and time mapping modes show that the relative standard deviation (RSD) in the intensity of the main Raman vibration modes (1079, 1586 cm(-1)) is less than 10%, demonstrating good spatial uniformity and time stability. This hybrid substrate also exhibits excellent SERS enhancement effect due to the formation of high-density hot spots among the AgNPs, which was proved by finite-difference time-domain (FDTD) simulations. The application of the new nanostructures as SERS sensors was demonstrated with the detection of malachite green (MG). The quantification of MG can be accomplished with the detection limit of 1 × 10(-12) M based on the Raman intensity. The results show that the Ag/TiO(2) nanostructure can be a promising candidate for SERS sensor.
ACS Applied Materials & Interfaces 06/2012; · 4.53 Impact Factor
