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Sample records for monodisperse silica nanospheres

  1. Monodispersed Silica Nanospheres Encapsulating Fe3O4 and LaF3:Eu3+ Nanoparticles for MRI Contrast Agent and Luminescent Imaging

    Science.gov (United States)

    Tian, Yang; Yu, Binbin; Yang, Hong-Yu; Liao, Ji

    2013-03-01

    Bifunctional nanospheres of silica encapsulating Fe3O4 and LaF3:Eu nanoparticles were synthesized in a reverse microemulsion solution. The nanospheres were perfectly monodispersed with a small diameter of 20 nm. The composition of the bifunctional nanospheres was confirmed by powder X-ray diffraction. Their magnetic and luminescent properties were measured at room temperature. The relaxation efficiency and T2-weighted images showed the high-performance for the product as a resonance imaging contrast agent. In addition, a qualitative cell uptake in human cervical cancer HeLa cells demonstrated that the SFLE nanospheres were efficiently up-taken into cytosol. Taken together, these findings suggest that the SiO2/Fe3O4-LaF3:Eu3+ nanospheres are good luminescence probes for bio-imaging.

  2. Synthesis and characterization of monodisperse Eu-doped luminescent silica nanospheres for biological applications

    Science.gov (United States)

    Enrichi, Francesco; Riccò, Raffaele; Parma, Alvise; Riello, Pietro; Benedetti, Alvise

    2008-04-01

    Luminescent nanoparticles are gaining more and more interest for bio-sensing and bio-imaging applications. In particular it is desiderable to work with cheap and non toxic materials which could be easily functionalized in their surface. To these respects silica nanoparticles seem to be a very promising and interesting solution. The liquid synthesis of silica spheres can be obtained by condensation of tetraethylortosilicate (TEOS) in basic or acid environment. Several strategies have been developed to make them luminescent by the incorporation of organic or inorganic emission centres, but often requiring multiple processing steps and use of expensive or toxic molecules. Moreover, common dyes suffer disadvantages such as a broad spectral band, short fluorescent lifetime and photobleaching. In contrast, rare earths exhibit narrow emission bands, large Stokes shifts and long luminescence lifetimes. In this work we focus our attention on the synthesis and characterization of europium-doped silica spheres. Europium introduction in the spheres can be interesting for biological applications to increase the signal to noise ratio due to the long luminescence lifetime (possibility to perform time-delayed analysis) and to the good emission intensity. The obtained results are presented and discussed, giving suggestions for the optimization of their morphological and optical properties. The possibility of realizing good luminescent silica spheres by following the described procedure is shown and suggestions for future development are given. The cheap and easy synthesis of these luminescent particles, the stability in water, the easy surface functionalization and bio-compatibility makes them very attractive in biological imaging and other applications.

  3. Investigation of luminescent dye-doped or rare-earth-doped monodisperse silica nanospheres for DNA microarray labelling

    Science.gov (United States)

    Enrichi, F.; Riccò, R.; Meneghello, A.; Pierobon, R.; Cretaio, E.; Marinello, F.; Schiavuta, P.; Parma, A.; Riello, P.; Benedetti, A.

    2010-10-01

    DNA microarray is a high-throughput technology used for detection and quantification of nucleic acid molecules and others of biological interest. The analysis is resulting by specific hybridization between probe sequences deposited in array and a target ss-DNA usually functionalized by a luminescent dye. These organic labels have well known disadvantages like photobleaching and limited sensitivity. Therefore in this work we investigate a different strategy, based on the use of inorganic silica nanospheres incorporating standard luminescent dyes or rare earth ions. The synthesis and characterization of these biomarkers is reported and their application to the DNA microarray technology in comparison to the use of standard molecular fluorophores or commercial quantum dots is discussed. We show that dye doped silica spheres provides a significant increase of the optical emission signal with respect to the use of free dyes, while rare earth doped silica spheres allow reducing or completely avoiding the background noise. These aspects, together with their cheap and easy synthesis, stability in water, easy surface functionalization and bio-compatibility makes them very promising for present and future applications in bio-labelling and bio-imaging.

  4. Luminescent dye-doped or rare-earth-doped monodisperse silica nanospheres as efficient labels in DNA microarrays

    Science.gov (United States)

    Enrichi, F.; Riccò, R.; Meneghello, A.; Pierobon, R.; Marinello, F.; Schiavuta, P.

    2009-08-01

    Luminescent nanoparticles are gaining more and more interest in bio-labeling and bio-imaging applications, like for example DNA microarray. This is a high-throughput technology used for detection and quantification of nucleic acid molecules and other ones of biological interest. The analysis is resulting by specific hybridization between probe sequences deposited in array and a target ss-DNA usually expressed by PCR and functionalized by a fluorescent dye. These organic labels have well known disadvantages like photobleaching and limited sensitivity. Quantum dots may be used as alternatives, but they present troubles like blinking, toxicity and excitation wavelengths out of the usual range of commercial instruments, lowering their efficiency. Therefore in this work we investigate a different strategy, based on the use of inorganic silica nanospheres incorporating standard luminescent dyes or rare earth doped nanocrystals. In the first case it is possible to obtain a high luminescence emission signal, due to the high number of dye molecules that can be accommodated into each nanoparticle, reduced photobleaching and environmental protection of the dye molecules thanks to the encapsulation in the silica matrix. In the second case, rare earths exhibit narrow emission bands (easy identification), large Stokes shifts (efficient discrimination of excitation and emission) and long luminescence lifetimes (possibility to perform time-delayed analysis) which can be efficiently used for the improvement of signal to noise ratio. The synthesis and characterization of good luminescent silica spheres either by organic dye-doping or by rare-earth-doping are investigated and reported. Moreover, their application in the DNA microarray technology in comparison to the use of standard molecular fluorophores or commercial quantum dots is discussed. The cheap and easy synthesis of these luminescent particles, the stability in water, the surface functionalization and bio

  5. Aerosol-Assisted Synthesis of Monodisperse Single-Crystalline α-Cristobalite Nanospheres

    OpenAIRE

    Jiang, Xingmao; Bao, Lihong; Cheng, Yung-Sung; Dunphy, Darren R.; Li, Xiaodong; Brinker, C. Jeffrey

    2011-01-01

    Monodisperse single-crystalline α-cristobalite nanospheres have been synthesized by hydrocarbon-pyrolysis-induced carbon deposition on amorphous silica aerosol nanoparticles, devitrification of the coated silica at high temperature, and subsequent carbon removal by oxidation. The nanosphere size can be well controlled by tuning the size of the colloidal silica precursor. Uniform, high-purity nanocrystalline α-cristobalite is important for catalysis, nanocomposites, advanced polishing, and und...

  6. Calculation of noncontact forces between silica nanospheres.

    Science.gov (United States)

    Sun, Weifu; Zeng, Qinghua; Yu, Aibing

    2013-02-19

    Quantification of the interactions between nanoparticles is important in understanding their dynamic behaviors and many related phenomena. In this study, molecular dynamics simulation is used to calculate the interaction potentials (i.e., van der Waals attraction, Born repulsion, and electrostatic interaction) between two silica nanospheres of equal radius in the range of 0.975 to 5.137 nm. The results are compared with those obtained from the conventional Hamaker approach, leading to the development of modified formulas to calculate the van der Waals attraction and Born repulsion between nanospheres, respectively. Moreover, Coulomb's law is found to be valid for calculating the electrostatic potential between nanospheres. The developed formulas should be useful in the study of the dynamic behaviors of nanoparticle systems under different conditions.

  7. Facile and Controlled Synthesis of Silica Sol Nanospheres Through a Modified Sol-Gel Process

    Institute of Scientific and Technical Information of China (English)

    LI Jie; CHEN Lianxi; ZHANG Zhongming; JIAO Caibin

    2014-01-01

    An effective and reproducible preparation of silica sol nanospheres via a modified sol-gel process has been described. Monodisperse and stable silica sol nanospheres with uniformsize were successfully obtained through the optimized synthesis in which the mixture of tetraethyl orthosilicate (TEOS) and ethanol was followed by the addition of water and ammonium hydroxide (NH3) separately, and the size of silica sol spheres was strictly controlled in the range of 25-119 nm with a narrow size distribution by fine adjustment of several reaction parameters. Results showed that in the presence of low concentration of TEOS, spheres size rose first and reached maximum when H2O concentration was up to 66 g/L. However, the diameter of silica sol spheres decreased above 66 g/L of H2O concentration. Furthermore, it was also found that the size and size distribution of silica sol nanospheres were affected by NH3 concentration. As NH3 concentration increased from 15 to 35 g/L, the diameter declined from 83 to 64 nm. Nevertheless, higher NH3 concentration would result in relatively broad size distribution, and gelation occurred when NH3 concentration reached 44 g/L. In addition, the effect of the different feed rates of NH3 on the size growth of silica sol nanospheres was also discussed.

  8. Morphology conserving aminopropyl functionalization of hollow silica nanospheres in toluene

    Science.gov (United States)

    Dobó, Dorina G.; Berkesi, Dániel; Kukovecz, Ákos

    2017-07-01

    Inorganic nanostructures containing cavities of monodisperse diameter distribution find applications in e.g. catalysis, adsorption and drug delivery. One of their possible synthesis routes is the template assisted core-shell synthesis. We synthesized hollow silica spheres around polystyrene cores by the sol-gel method. The polystyrene template was removed by heat treatment leaving behind a hollow spherical shell structure. The surface of the spheres was then modified by adding aminopropyl groups. Here we present the first experimental evidence that toluene is a suitable alternative functionalization medium for the resulting thin shells, and report the comprehensive characterization of the amino-functionalized hollow silica spheres based on scanning electron microscopy, transmission electron microscopy, N2 adsorption, FT-IR spectroscopy, Raman spectroscopy and electrokinetic potential measurement. Both the presence of the amino groups and the preservation of the hollow spherical morphology were unambiguously proven. The introduction of the amine functionality adds amphoteric character to the shell as shown by the zeta potential vs. pH function. Unlike pristine silica particles, amino-functionalized nanosphere aqueous sols can be stable at both acidic and basic conditions.

  9. Facile Method for Preparation of Silica Coated Monodisperse Superparamagnetic Microspheres

    Directory of Open Access Journals (Sweden)

    Xuan-Hung Pham

    2016-01-01

    Full Text Available This paper presents a facile method for preparation of silica coated monodisperse superparamagnetic microsphere. Herein, monodisperse porous polystyrene-divinylbenzene microbeads were prepared by seeded emulsion polymerization and subsequently sulfonated with acetic acid/H2SO4. The as-prepared sulfonated macroporous beads were magnetized in presence of Fe2+/Fe3+ under alkaline condition and were subjected to silica coating by sol-gel process, providing water compatibility, easily modifiable surface form, and chemical stability. FE-SEM, TEM, FT-IR, and TGA were employed to characterize the silica coated monodisperse magnetic beads (~7.5 μm. The proposed monodisperse magnetic beads can be used as mobile solid phase particles candidate for protein and DNA separation.

  10. The preparation of core-shell magnetic silica nanospheres for enhancing magnetism and fluorescence intensity.

    Science.gov (United States)

    Yoo, Jeong Ha; Kim, Jong Sung

    2013-11-01

    Recently, magnetic and luminescent composite silica with structure of micro- and nanospheres containing both magnetic (Fe3O4) nanoparticles (MPs) and quantum dots (QDs) has attracted great interests. In this study, we have prepared core-shell structure of silica spheres in which magnets are incorporated into silica core and QDs into a mesoporous silica shell by using C18-TMS (octade-cyltrimethoxysilane). MPs were synthesized by a co-precipitation method from ferrous and ferric solutions with a molecular ratio of 2:3. Monodisperse magnetic silica cores have been prepared via sol-gel reaction of TEOS (tetraethoxysilane) and water using base catalyst. The size of magnetic silica nanospheres was confirmed by dynamic laser light scattering system (DLS) and scanning electoron microscope (SEM). The pore volume and surface area were calculated by using BET after calcination. The core-shell structure plays an important role in providing more domains for MPs in silica Core and QDs in silica shell. QDs were incorporated into the mesoporous shell by hydrophobic interactions. Magnetic characterization was performed using a superconducting quantum interference device (SQUID). The optical properties of the particles were characterized with UV/Vis spectrometer, PL spectrometer, and fluorescence microscope.

  11. A facile method to produce highly monodispersed nanospheres of cystine aggregates

    Science.gov (United States)

    Han, Hongliang; Wang, Chungang; Ma, Zhanfang; Su, Zhongmin

    2006-10-01

    Multiple shapes of nano- and micro-structured cystine aggregates, including spheres, rods, spindles, dendrites, and multipods, were easily synthesized just by adjusting the concentrations and pH values of L-Cysteine solutions under ultrasonic irritation. Importantly, highly monodispersed nanospheres of cystine aggregates 225 nm in diameter without any other shapes were easily obtained for the system of 0.1 M L-Cysteine with pH 8. This will provide a very simple and effective approach to produce monodispersed cystine microspheres, which could promote new possibilities for future applications in biosensor, drug delivery, medicine, and the production of nanomaterials.

  12. A facile method to produce highly monodispersed nanospheres of cystine aggregates

    Energy Technology Data Exchange (ETDEWEB)

    Han Hongliang; Wang Chungang; Ma Zhanfang; Su Zhongmin [Chemistry Department, Northeast Normal University, Changchun 130024 (China)

    2006-10-28

    Multiple shapes of nano- and micro-structured cystine aggregates, including spheres, rods, spindles, dendrites, and multipods, were easily synthesized just by adjusting the concentrations and pH values of L-Cysteine solutions under ultrasonic irritation. Importantly, highly monodispersed nanospheres of cystine aggregates 225 nm in diameter without any other shapes were easily obtained for the system of 0.1 M L-Cysteine with pH 8. This will provide a very simple and effective approach to produce monodispersed cystine microspheres, which could promote new possibilities for future applications in biosensor, drug delivery, medicine, and the production of nanomaterials.

  13. Facile synthesis of monodisperse superparamagnetic Fe3O4/PMMA composite nanospheres with high magnetization

    Science.gov (United States)

    Lan, Fang; Liu, Ke-Xia; Jiang, Wen; Zeng, Xiao-Bo; Wu, Yao; Gu, Zhong-Wei

    2011-06-01

    Monodisperse superparamagnetic Fe3O4/polymethyl methacrylate (PMMA) composite nanospheres with high saturation magnetization were successfully prepared by a facile novel miniemulsion polymerization method. The ferrofluid, MMA monomer and surfactants were co-sonicated and emulsified to form stable miniemulsion for polymerization. The samples were characterized by DLS, TEM, FTIR, XRD, TGA and VSM. The diameter of the Fe3O4/PMMA composite nanospheres by DLS was close to 90 nm with corresponding polydispersity index (PDI) as small as 0.099, which indicated that the nanospheres have excellent homogeneity in aqueous medium. The TEM results implied that the Fe3O4/PMMA composite nanospheres had a perfect core-shell structure with about 3 nm thin PMMA shells, and the core was composed of many homogeneous and closely packed Fe3O4 nanoparticles. VSM and TGA showed that the Fe3O4/PMMA composite nanospheres with at least 65% high magnetite content were superparamagnetic, and the saturation magnetization was as high as around 39 emu g - 1 (total mass), which was only decreased by 17% compared with the initial bare Fe3O4 nanoparticles.

  14. Synthesis of Hollow Silica Nanospheres by Sacrificial Polystyrene Templates for Thermal Insulation Applications

    Directory of Open Access Journals (Sweden)

    Linn Ingunn C. Sandberg

    2013-01-01

    Full Text Available Monodisperse polystyrene (PS spheres with controllable size have been synthesized by a straight forward and simple procedure. The as-synthesized PS spheres have a typical diameter ranging from ~180 nm to ~900 nm, where a reduced sphere size is obtained by increasing the polyvinylpyrrolidone (PVP/styrene weight ratio. The PS spheres function as sacrificial templates for the fabrication of hollow silica nanospheres (HSNSs for thermal insulation applications. By modifying the silica coating process, HSNSs with different surface roughness are obtained. All resulting HSNSs show typically a thermal conductivity of about 20 mW/(mK, indicating that the surface phonon scattering is probably not significant in these HSNS samples.

  15. Investigation on raspberry-like magnetic-hollow silica nanospheres and its preliminary application for drug delivery

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Chunlei; Yan, Juntao, E-mail: yanjuntaonihao@163.com [Wuhan Polytechnic University, College of Chemistry and Environmental Engineering (China); Li, Zhanfeng; Wang, Hongyan; Cui, Xuejun [Jilin University, College of Chemistry (China)

    2013-09-15

    A series of raspberry-like magnetic-hollow silica nanospheres were successfully synthesized via the sol-gel process, which was based on the principle of the electrostatic interaction between negatively charged silica and positively charged polystyrene. The Fe{sub 3}O{sub 4}@SiO{sub 2} particles as the outer shell were compactly assembled on the surface of PS, and then magnetic-hollow nanospheres were obtained by calcination. Different synthesis conditions including the amount of NH{sub 4}OH, TEOS, Fe{sub 3}O{sub 4}, and the adding time of PS were systematically investigated to discuss the influence of these conditions on the morphology and structure. The prepared magnetic-hollow nanospheres were systematically characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), fourier transform infrared spectrometry, energy-dispersive X-ray analysis, thermogravimetric analysis and nitrogen adsorption-desorption measurement. SEM and TEM images exhibited that the obtained samples with the perfect spherical profile and large cavities structure were well monodisperse and uniform under the optimized condition. Zeta-potential analysis was employed to make clear the formation mechanism of raspberry-like PS@Fe{sub 3}O{sub 4}@SiO{sub 2} composite nanosphere. Moreover, the drug release of ibuprofen experiment results demonstrated that the magnetic-hollow nanospheres could be used as a drug carrier to slowly release and deliver drugs.

  16. Synthesis of silica nanosphere from homogeneous and heterogeneous systems

    Indian Academy of Sciences (India)

    N Venkatathri

    2007-12-01

    Silica nanosphere was synthesized using homogeneous and heterogeneous systems, respectively. In homogeneous system, silica spheres were synthesized without cetyltrimethylammonium bromide (CTABr), which gave bimodal particle size and lower yield (77%). To improve the yield, CTABr was added and found that the yield was very high (100%). The particle was in nm range, but the particle sizes are bimodal. To avoid it, reaction in heterogeneous system using CTABr was carried out. Nanosized silica sphere with uniform size (yield, 94%) was observed. Homogeneous system contains a mixture of ethanol, water, aqueous ammonia and tetraethylorthosilicate (TEOS). In the case of heterogeneous system, only ethanol was absent.

  17. Formation of monodisperse mesoporous silica microparticles via spray-drying.

    Science.gov (United States)

    Waldron, Kathryn; Wu, Winston Duo; Wu, Zhangxiong; Liu, Wenjie; Selomulya, Cordelia; Zhao, Dongyuan; Chen, Xiao Dong

    2014-03-15

    In this work, a protocol to synthesize monodisperse mesoporous silica microparticles via a unique microfluidic jet spray-drying route is reported for the first time. The microparticles demonstrated highly ordered hexagonal mesostructures with surface areas ranging from ~900 up to 1500 m(2)/g and pore volumes from ~0.6 to 0.8 cm(3)/g. The particle size could be easily controlled from ~50 to 100 μm from the same diameter nozzle via changing the initial solute content, or changing the drying temperature. The ratio of the surfactant (CTAB) and silica (TEOS), and the amount of water in the precursor were found to affect the degree of ordering of mesopores by promoting either the self-assembly of the surfactant-silica micelles or the condensation of the silica as two competing processes in evaporation induced self-assembly. The drying rate and the curvature of particles also affected the self-assembly of the mesostructure. The particle mesostructure is not influenced by the inlet drying temperature in the range of 92-160 °C, with even a relatively low temperature of 92 °C producing highly ordered mesoporous microparticles. The spray-drying derived mesoporous silica microparticles, while of larger sizes and more rapidly synthesized, showed a comparable performance with the conventional mesoporous silica MCM-41 in controlled release of a dye, Rhodamine B, indicating that these spray dried microparticles could be used for the immobilisation and controlled release of small molecules.

  18. Tribological characteristics of monodispersed cerium borate nanospheres in biodegradable rapeseed oil lubricant

    Science.gov (United States)

    Boshui, Chen; Kecheng, Gu; Jianhua, Fang; Jiang, Wu; Jiu, Wang; Nan, Zhang

    2015-10-01

    Stearic acid-capped cerium borate composite nanoparticles, abbreviated as SA/CeBO3, were prepared by hydrothermal method. The morphologies, element compositions, size distributions, crystal and chemical structures, hydrophobic characteristics, of SA/CeBO3 were characterized by scanning electron microscope, energy dispersive X-ray spectrometer, dynamic laser particle size analyzer, X-ray diffraction, and Fourier transform infrared spectrometer, respectively. The friction and wear performances of SA/CeBO3 as a lubricating additive in a rapeseed oil were evaluated on a four-ball tribo-tester. The tribochemical characteristics of the worn surfaces were investigated by X-ray photoelectron spectroscopy. The results showed that the hydrophobic SA/CeBO3 were monodispersed nanospheres with an average diameter of 8 nm, and exhibited excellent dispersing stability in rapeseed oil. Meanwhile, SA/CeBO3 nanospheres were outstanding in enhancing friction-reducing and anti-wear capacities of rapeseed oil. The prominent tribological performances of SA/CeBO3 in rapeseed oil were attributed to the formation of a composite boundary lubrication film mainly composed of lubricous tribochemical species of B2O3, CeO2 and Fe2O3, and the adsorbates of SA/CeBO3 and rapeseed oil, on the tribo-surfaces.

  19. Templated Control of Au nanospheres in Silica Nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Tringe, J W; Vanamu, G; Zaidi, S H

    2007-03-15

    The formation of regularly-spaced metal nanostructures in selectively-placed insulating nanowires is an important step toward realization of a wide range of nano-scale electronic and opto-electronic devices. Here we report templated synthesis of Au nanospheres embedded in silica nanowires, with nanospheres consistently spaced with a period equal to three times their diameter. Under appropriate conditions, nanowires form exclusively on Si nanostructures because of enhanced local oxidation and reduced melting temperatures relative to templates with larger dimensions. We explain the spacing of the nanospheres with a general model based on a vapor-liquid-solid mechanism, in which an Au/Si alloy dendrite remains liquid in the nanotube until a critical Si concentration is achieved locally by silicon oxide-generated nanowire growth. Additional Si oxidation then locally reduces the surface energy of the Au-rich alloy by creating a new surface with minimum area inside of the nanotube. The isolated liquid domain subsequently evolves to become an Au nanosphere, and the process is repeated.

  20. Optical properties of gold nanoshells on monodisperse silica cores: Experiment and simulations

    Science.gov (United States)

    Khanadeev, Vitaly A.; Khlebtsov, Boris N.; Khlebtsov, Nikolai G.

    2017-01-01

    Gold nanoshells (GNSs) on silica cores are widely used in various biomedical applications that need the spectral tunability and controlled absorption/scattering ratio. However, the plasmonic quality of experimental extinction spectra of GNS colloids differs from that predicted by Mie theory. In this work, we fabricated highly monodisperse silica nanospheres to use them further as cores for synthesis of silica/gold nanoshells. Four GNS samples with 116-nm core and gold shell thickness ranging from 16 to 34 nm (116/16, 18, 25, 34) were additionally separated in glycerol gradient solutions to obtain fractions with dominant percentage of single particles or aggregates of various sizes. The separated samples demonstrated extinction spectra with a high extinction maximum to minimum ratio about 3. Optical properties of GNS monomers and aggregates with fixed and random orientations were calculated by Mie theory for polydisperse GNSs, by a generalized multiparticle Mie (GMM) theory for aggregates of separated GNSs, and by the finite-difference time-domain (FDTD) method for aggregates of overlapped GNSs. The extinction spectra of upper fractions from 116/25 and 116/34 samples are shown to be well described by Mie theory for GNSs with polydisperse shell thickness. However, for as prepared 116/16 sample this approach fails because of strong near infrared (NIR) contribution from GNS dimers and trimers. The formation of such aggregates is due to coupling of silica cores at early stages of nanoshell synthesis, thus leading to peanut structures with overlapped gold shells. We suggested TEM-based ensemble model with single particles and small dimer and trimer aggregates, which gives satisfactory agreement between measured and FDTD simulated spectra in the vis-NIR region. Thus, the proposed synthetic technology produces high quality gold nanoshells, which remarkable optical properties are in good agreement with electromagnetic simulations based on TEM data.

  1. Synthesis of Reusable Silica Nanosphere-Supported Pt(IV) Complex for Formation of Disulfide Bonds in Peptides.

    Science.gov (United States)

    Hou, Xiaonan; Zhao, Xiaowei; Zhang, Yamei; Han, Aiying; Huo, Shuying; Shen, Shigang

    2017-02-22

    Some peptide-based drugs, including oxytocin, vasopressin, ziconotide, pramlintide, nesiritide, and octreotide, contain one intramolecular disulfide bond. A novel and reusable monodispersed silica nanosphere-supported Pt(IV) complex (SiO₂@TPEA@Pt(IV)); TPEA: N-[3-(trimethoxysilyl)propyl]ethylenediamine) was synthesized via a four-step procedure and was used for the formation of intramolecular disulfide bonds in peptides. Transmission electron microscopy (TEM) and chemical mapping results for the Pt(II) intermediates and for SiO₂@TPEA@Pt(IV) show that the silica nanospheres possess a monodisperse spherical structure and contain uniformly-distributed Si, O, C, N, Cl, and Pt. The valence state of Pt on the silica nanospheres was characterized by X-ray photoelectron spectroscopy (XPS). The Pt(IV) loaded on SiO₂@TPEA@Pt(IV) was 0.15 mmol/g, as determined by UV-VIS spectrometry. The formation of intramolecular disulfides in six dithiol-containing peptides of variable lengths by the use of SiO₂@TPEA@Pt(IV) was investigated, and the relative oxidation yields were determined by high-performance liquid chromatography (HPLC). In addition, peptide 1 (Ac-CPFC-NH₂) was utilized to study the reusability of SiO₂@TPEA@Pt(IV). No significant decrease in the relative oxidation yield was observed after ten reaction cycles. Moreover, the structure of SiO₂@TPEA@Pt(IV) after being used for ten cycles was determined to be similar to its initial one, demonstrating the cycling stability of the complex.

  2. Synthesis of Reusable Silica Nanosphere-Supported Pt(IV Complex for Formation of Disulfide Bonds in Peptides

    Directory of Open Access Journals (Sweden)

    Xiaonan Hou

    2017-02-01

    Full Text Available Some peptide-based drugs, including oxytocin, vasopressin, ziconotide, pramlintide, nesiritide, and octreotide, contain one intramolecular disulfide bond. A novel and reusable monodispersed silica nanosphere-supported Pt(IV complex (SiO2@TPEA@Pt(IV; TPEA: N-[3-(trimethoxysilylpropyl]ethylenediamine was synthesized via a four-step procedure and was used for the formation of intramolecular disulfide bonds in peptides. Transmission electron microscopy (TEM and chemical mapping results for the Pt(II intermediates and for SiO2@TPEA@Pt(IV show that the silica nanospheres possess a monodisperse spherical structure and contain uniformly-distributed Si, O, C, N, Cl, and Pt. The valence state of Pt on the silica nanospheres was characterized by X-ray photoelectron spectroscopy (XPS. The Pt(IV loaded on SiO2@TPEA@Pt(IV was 0.15 mmol/g, as determined by UV-VIS spectrometry. The formation of intramolecular disulfides in six dithiol-containing peptides of variable lengths by the use of SiO2@TPEA@Pt(IV was investigated, and the relative oxidation yields were determined by high-performance liquid chromatography (HPLC. In addition, peptide 1 (Ac-CPFC-NH2 was utilized to study the reusability of SiO2@TPEA@Pt(IV. No significant decrease in the relative oxidation yield was observed after ten reaction cycles. Moreover, the structure of SiO2@TPEA@Pt(IV after being used for ten cycles was determined to be similar to its initial one, demonstrating the cycling stability of the complex.

  3. Tribological characteristics of monodispersed cerium borate nanospheres in biodegradable rapeseed oil lubricant

    Energy Technology Data Exchange (ETDEWEB)

    Boshui, Chen, E-mail: boshuichen@163.com; Kecheng, Gu; Jianhua, Fang; Jiang, Wu; Jiu, Wang; Nan, Zhang

    2015-10-30

    Graphical abstract: - Highlights: • Monodispersed stearic acid-capped cerium borate composite nanoparticles were prepared by hydrothermal method. Their morphologies, element compositions, size distributions, crystal and chemical structures, hydrophobic characteristics were also characterized. • The surface-capped cerium borate nanoparticles exhibited excellent dispersing stability in rapeseed oil. As new lubricating additives, they were also outstanding in enhancing friction-reducing and anti-wear capacities of rapeseed oil in biodegradable rapeseed oil. The results presented in this paper would be of important significance for developing green lubricants and lubricant additives. • The prominent tribological performances of SA/CeBO{sub 3} in rapeseed oil were investigated and attributed to the formation of a composite boundary lubrication film mainly composed of lubricous tribochemical species on the tribo-surfaces. - Abstract: Stearic acid-capped cerium borate composite nanoparticles, abbreviated as SA/CeBO{sub 3}, were prepared by hydrothermal method. The morphologies, element compositions, size distributions, crystal and chemical structures, hydrophobic characteristics, of SA/CeBO{sub 3} were characterized by scanning electron microscope, energy dispersive X-ray spectrometer, dynamic laser particle size analyzer, X-ray diffraction, and Fourier transform infrared spectrometer, respectively. The friction and wear performances of SA/CeBO{sub 3} as a lubricating additive in a rapeseed oil were evaluated on a four-ball tribo-tester. The tribochemical characteristics of the worn surfaces were investigated by X-ray photoelectron spectroscopy. The results showed that the hydrophobic SA/CeBO{sub 3} were monodispersed nanospheres with an average diameter of 8 nm, and exhibited excellent dispersing stability in rapeseed oil. Meanwhile, SA/CeBO{sub 3} nanospheres were outstanding in enhancing friction-reducing and anti-wear capacities of rapeseed oil. The prominent

  4. Silica nanospheres formation induced by peroxidase-catalyzed phenol polymerization

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    To examine whether lignin-like compound is correlated with silica precipitation in grass, a series of simulated chemical experiments were carried out at ambient temperature and pressure, close to cell wall pH, with phenol polymerization catalyzed by peroxidase in silicon solution. The experiments showed that phenol polymer (a kind of lignin-like substance) caused silica nanosphere precipitation similar to those caused by protein in diatom cell wall previously reported by other authors. The sphere diameter varied with different kinds of phenol and the concentrations of phenol and silicon. Silicon precipitation had phenol and silicon saturation effect, meaning that when the concentration ratio of soluble silicon to phenol exceeded a certain value, the amount of silicon precipitation would decrease.

  5. Synthesis, photocatalytic activity, and photogenerated hydroxyl radicals of monodisperse colloidal ZnO nanospheres

    Science.gov (United States)

    Yang, Chong; Li, Qingsong; Tang, Limei; Xin, Kun; Bai, Ailing; Yu, Yingmin

    2015-12-01

    In the present study, monodisperse colloidal zinc oxide (ZnO) nanospheres were successfully synthesized via a newly developed two-stage solution method followed by facile calcination at various temperatures. The effects of calcination temperature on the structure, morphology, and optical properties as well as the photocatalytic activity of the as-made ZnO samples were investigated systematically by Fourier transform infrared spectrometry, X-ray diffraction, field emission scanning electron microscopy, nitrogen adsorption/desorption isotherms, diffuse reflectance UV-visible spectroscopy (DRS), photoluminescence, and related photocatalytic activity tests. The thermal decomposition was analyzed by thermogravimetric analysis. The crystallinity was found to gradually increase with increasing calcination temperature, whereas the decrease in the Brunauer-Emmett-Teller specific surface area of the samples with calcination may be ascribed to the increased particle size. The DRS results provided clear evidence for the decrease in band gap energy of ZnO samples with an increase in calcination temperature. The photoluminescence spectra demonstrated the calcination-dependent emission features, especially the UV emission intensity. In particular, the ZnO product calcined at 400 °C exhibited the highest photocatalytic activity, degrading methylene blue by almost 99.1% in 70 min, which is ascribed to the large specific surface area and pore volume, high electron-hole pair separation efficient, and great redox potential of the obtained ZnO nanoparticles. In addition, the production of photogenerated hydroxyl radicals (•OH) was consistent with the methylene blue degradation efficiency over the as-made ZnO nanoparticles. Using isopropanol as a hydroxyl radical scavenger, •OH was determined to be the main active oxygen species in the photocatalytic process. A possible mechanism of photodegradation under UV light irradiation also is proposed.

  6. Sustained release of fungicide metalaxyl by mesoporous silica nanospheres

    Energy Technology Data Exchange (ETDEWEB)

    Wanyika, Harrison, E-mail: hwanyika@gmail.com [Jomo Kenyatta University of Agriculture and Technology, Department of Chemistry (Kenya)

    2013-08-15

    The use of nanomaterials for the controlled delivery of pesticides is nascent technology that has the potential to increase the efficiency of food production and decrease pollution. In this work, the prospect of mesoporous silica nanoparticles (MSN) for storage and controlled release of metalaxyl fungicide has been investigated. Mesoporous silica nanospheres with average particle diameters of 162 nm and average pore sizes of 3.2 nm were prepared by a sol-gel process. Metalaxyl molecules were loaded into MSN pores from an aqueous solution by a rotary evaporation method. The loaded amount of metalaxyl as evaluated by thermogravimetric analysis was about 14 wt%. Release of the fungicide entrapped in the MSN matrix revealed sustained release behavior. About 76 % of the free metalaxyl was released in soil within a period of 30 days while only 11.5 and 47 % of the metalaxyl contained in the MSN carrier was released in soil and water, respectively, within the same period. The study showed that MSN can be used to successfully store metalaxyl molecules in its mesoporous framework and significantly delay their release in soil.

  7. Sustained release of fungicide metalaxyl by mesoporous silica nanospheres

    Science.gov (United States)

    Wanyika, Harrison

    2013-08-01

    The use of nanomaterials for the controlled delivery of pesticides is nascent technology that has the potential to increase the efficiency of food production and decrease pollution. In this work, the prospect of mesoporous silica nanoparticles (MSN) for storage and controlled release of metalaxyl fungicide has been investigated. Mesoporous silica nanospheres with average particle diameters of 162 nm and average pore sizes of 3.2 nm were prepared by a sol-gel process. Metalaxyl molecules were loaded into MSN pores from an aqueous solution by a rotary evaporation method. The loaded amount of metalaxyl as evaluated by thermogravimetric analysis was about 14 wt%. Release of the fungicide entrapped in the MSN matrix revealed sustained release behavior. About 76 % of the free metalaxyl was released in soil within a period of 30 days while only 11.5 and 47 % of the metalaxyl contained in the MSN carrier was released in soil and water, respectively, within the same period. The study showed that MSN can be used to successfully store metalaxyl molecules in its mesoporous framework and significantly delay their release in soil.

  8. Synthesis of Monodispersed Tantalum(V) oxide Nanospheres by an Ethylene Glycol Mediated Route

    Science.gov (United States)

    Tantalum(V) oxide (Ta2O5) nanospheres have been synthesized by a very simple ethylene glycol mediated route. The two-step process involves the formation of glycolate nanoparticles and their subsequent hydrolysis and calcination to generate the final Ta2O5 nanospheres. The synthes...

  9. Bio-physical evaluation and in vivo delivery of plant proteinase inhibitor immobilized on silica nanospheres.

    Science.gov (United States)

    Khandelwal, Neha; Doke, Dhananjay S; Khandare, Jayant J; Jawale, Priyanka V; Biradar, Ankush V; Giri, Ashok P

    2015-06-01

    Recombinant expression of Capsicum annuum proteinase inhibitors (CanPI-13) and its application via synthetic carrier for the crop protection is the prime objective of our study. Herein, we explored proteinase inhibitor peptide immobilization on silica based nanospheres and rods followed by its pH mediated release in vitro and in vivo. Initial studies suggested silica nanospheres to be a suitable candidate for peptide immobilization. Furthermore, the interactions were characterized biophysically to ascertain their conformational stability and biological activity. Interestingly, bioactive peptide loading at acidic pH on nanospheres was found to be 62% and showed 56% of peptide release at pH 10, simulating gut milieu of the target pest Helicoverpa armigera. Additionally, in vivo study demonstrated significant reduction in insect body mass (158 mg) as compared to the control insects (265 mg) on 8th day after feeding with CanPI-13 based silica nanospheres. The study confirms that peptide immobilized silica nanosphere is capable of affecting overall growth and development of the feeding insects, which is known to hamper fecundity and fertility of the insects. Our study illustrates the utility and development of peptide-nanocarrier based platform in delivering diverse biologically active complexes specific to gut pH of H. armigera.

  10. Studies on the annealing and antibacterial properties of the silver-embedded aluminum/silica nanospheres

    Science.gov (United States)

    Pan, Ko-Ying; Chien, Chia-Hung; Pu, Ying-Chih; Liu, Chia-Ming; Hsu, Yung-Jung; Yeh, Jien-Wei; Shih, Han C.

    2014-06-01

    Substantial silver-embedded aluminum/silica nanospheres with uniform diameter and morphology were successfully synthesized by sol-gel technique. After various annealing temperatures, the surface mechanisms of each sample were analyzed using scanning electron microscope, transmission electron microscope, and X-ray photoelectron spectroscopy. The chemical durability examinations and antibacterial tests of each sample were also carried out for the confirmation of its practical usage. Based on the result of the above analyses, the silver-embedded aluminum/silica nanospheres are eligible for fabricating antibacterial utensils.

  11. Facile Synthesis and Characterization of Au Nanoclusters-Silica Fluorescent Composite Nanospheres

    Directory of Open Access Journals (Sweden)

    Huiping Wang

    2013-01-01

    Full Text Available We developed a novel method for the synthesis of Au nanoclusters (NCs silica fluorescent composite nanospheres by mixing the as-prepared bovine serum albumin (BSA protected Au NCs with amino-modified silica spheres in acetate buffer solution. The products were characterized by high-resolution transmission electron microscopy (HRTEM, X-ray photoelectron spectroscopy (XPS, fluorescent microscope imaging (FLMI, and dynamic light scattering (DLS measurements. The proposed method was simple, efficient, and inexpensive. In addition, the composite nanospheres exhibited favorable water-dispersible, stable, and fluorescent properties, potentially leading to further applications in chemical and biological sensors. A reasonable mechanism was also proposed for the formation of composite nanospheres.

  12. High-surface-area silica nanospheres (KCC-1) with a fibrous morphology

    KAUST Repository

    Polshettiwar, Vivek

    2010-08-02

    Fibrous nanosilica: A new family of high-surface-area silica nanospheres (KCC-1) have been prepared (see picture). KCC-1 features excellent physical properties, including high surface area, unprecedented fibrous surface morphology, high thermal (up to 950 °C) and hydrothermal stabilities, and high mechanical stability. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Monodisperse cobalt ferrite nanomagnets with uniform silica coatings.

    Science.gov (United States)

    Dai, Qiu; Lam, Michelle; Swanson, Sally; Yu, Rui-Hui Rachel; Milliron, Delia J; Topuria, Teya; Jubert, Pierre-Olivier; Nelson, Alshakim

    2010-11-16

    Ferro- and ferrimagnetic nanoparticles are difficult to manipulate in solution as a consequence of the formation of magnetically induced nanoparticle aggregates, which hamper the utility of these particles for applications ranging from data storage to bionanotechnology. Nonmagnetic shells that encapsulate these magnetic particles can reduce the interparticle magnetic interactions and improve the dispersibility of the nanoparticles in solution. A route to create uniform silica shells around individual cobalt ferrite nanoparticles--which uses poly(acrylic acid) to bind to the nanoparticle surface and inhibit nanoparticle aggregation prior to the addition of a silica precursor--was developed. In the absence of the poly(acrylic acid) the cobalt ferrite nanoparticles irreversibly aggregated during the silica shell formation. The thickness of the silica shell around the core-shell nanoparticles could be controlled in order to tune the interparticle magnetic coupling as well as inhibit magnetically induced nanoparticle aggregation. These ferrimagnetic core-silica shell structures form stable dispersion in polar solvents such as EtOH and water, which is critical for enabling technologies that require the assembly or derivatization of ferrimagnetic particles in solution.

  14. The Preparation of Magnetic Silica Nanospheres and Incorporation of CdSe/ZnS Quantum Dots-DNA Probe.

    Science.gov (United States)

    Do, Youngjin; Kim, Jongsung

    2016-03-01

    Silica nanospheres containing magnetic particles were prepared, and CdSe/ZnS QDs functionalized with carboxyl group were incorporated into the silica nanospheres by EDC/NHS coupling reaction. The silica nanospheres were prepared by a co-precipitation of ferrous and ferric solutions followed by the sol-gel reaction of TEOS (tetraethoxysilane) and APTES (3-aminopropyltriethoxysilane) using base catalyst. The size of magnetic silica nanospheres was confirmed by Transmission electron microscope (TEM). Thiol group modified single stranded oligonucleotides were immobilized on the surface of QDs and fluorescence quenching by intercalation dye (TOTO-3) after hybridization with target oligonucleotide was observed. The fluorescence from QDs could be quenched by intercalating dye (TOTO-3) after hybridization of target DNA to probe DNA. This shows that the magnetic silica-QD-DNA probe can be used to detect specific DNA.

  15. Monodisperse spherical meso-macroporous silica particles: Synthesis and adsorption of biological macromolecules

    Science.gov (United States)

    Stovpiaga, E. Yu.; Grudinkin, S. A.; Kurdyukov, D. A.; Kukushkina, Yu. A.; Nashchekin, A. V.; Sokolov, V. V.; Yakovlev, D. R.; Golubev, V. G.

    2016-11-01

    Monodispersed spherical silica particles, including large mesopores (over 10 nm) and macropores (up to 100 nm) were obtained by chemical etching in an autoclave. A method for introducing globular protein myoglobin molecules into the pores is developed. The method of filling is based on a high adsorption capacity of the developed internal pore structure of the particles. The structure and adsorption properties of the materials are studied.

  16. Preparation and characterization of monodisperse large-porous silica microspheres as the matrix for protein separation.

    Science.gov (United States)

    Xia, Hongjun; Wan, Guangping; Zhao, Junlong; Liu, Jiawei; Bai, Quan

    2016-11-04

    High performance liquid chromatography (HPLC) is a kind of efficient separation technology and has been used widely in many fields. Micro-sized porous silica microspheres as the most popular matrix have been used for fast separation and analysis in HPLC. In this paper, the monodisperse large-porous silica microspheres with controllable size and structure were successfully synthesized with polymer microspheres as the templates and characterized. First, the poly(glycidyl methacrylate-co-ethyleneglycol dimethacrylate) microspheres (PGMA-EDMA) were functionalized with tetraethylenepentamine (TEPA) to generate amino groups which act as a catalyst in hydrolysis of tetraethyl orthosilicate (TEOS) to form Si-containing low molecular weight species. Then the low molecular weight species diffused into the functionalized PGMA-EDMA microspheres by induction force of the amino groups to form polymer/silica hybrid microspheres. Finally, the organic polymer templates were removed by calcination, and the large-porous silica microspheres were obtained. The compositions, morphology, size distribution, specific surface area and pore size distribution of the porous silica microspheres were characterized by infrared analyzer, scanning-electron microscopy, dynamic laser scattering, the mercury intrusion method and thermal gravimetric analysis, respectively. The results show that the agglomeration of the hybrid microspheres can be overcome when the templates were functionalized with TEPA as amination reagent, and the yield of 95.7% of the monodisperse large-porous silica microspheres can be achieved with high concentration of polymer templates. The resulting large-porous silica microspheres were modified with octadecyltrichlorosilane (ODS) and the chromatographic evaluation was performed by separating the proteins and the digest of BSA. The baseline separation of seven kinds of protein standards was achieved, and the column delivered a better performance when separating BSA digests

  17. Core-shell structured nanospheres with mesoporous silica shell and Ni core as a stable catalyst for hydrolytic dehydrogenation of ammonia borane

    Institute of Scientific and Technical Information of China (English)

    Hua; Liu; Changyan; Cao; Ping; Li; Yu; Yu; Weiguo; Song

    2014-01-01

    Core-shell structured nanospheres with mesoporous silica shell and Ni core(denoted as Ni@meso-SiO2) are prepared through a three-step process. Monodispersed Ni precursors are first prepared, and then coated with mesoporous SiO2. Final Ni@meso-SiO2spheres are obtained after calcination. The products are characterized by X-ray powder diffraction, transmission electron microscopy and N2adsorption-desorption methods. These spheres have a high surface area and are well dispersed in water, showing a high catalytic activity with a TOF value of 18.5,and outstanding stability in hydrolytic dehydrogenation of ammonia borane at room temperature.

  18. Protein Localization in Silica Nanospheres Derived via Biomimetic Mineralization (POSTPRINT)

    Science.gov (United States)

    2010-01-01

    can be used for characterizing a wide range of mesoporous and ultrastructural materials. neutron scattering, silica, lysozyme, biomineralization U U...used for characterizing a wide range of mesoporous and ultrastructural materials. FU LL P A P ER © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Adv...The nitrogen adsorption isotherms of the silica-lysozyme composites show typical type IV characteristics, with hysteresis indicative of a

  19. Monodisperse core-shell particles composed of magnetite and dye-functionalized mesoporous silica

    Science.gov (United States)

    Eurov, D. A.; Kurdyukov, D. A.; Medvedev, A. V.; Kirilenko, D. A.; Yakovlev, D. R.; Golubev, V. G.

    2017-08-01

    Hybrid particles with a core-shell structure have been obtained in the form of monodisperse spherical mesoporous silica particles filled with magnetite and covered with a mesoporous silica shell functionalized with a luminescent dye. The particles have a small root-mean-square size deviation (at most 10%), possess a specific surface area and specific pore volume of up to 250 m2/g and 0.15 cm3/g, respectively, and exhibit visible luminescence peaked at a wavelength of 530 nm. The particles can be used in diagnostics of cancerous diseases, serving simultaneously for therapeutic (magnetic hyperthermia and targeted drug delivery) and diagnostic (contrast agent for magnetic-resonance tomography and luminescent marker) purposes.

  20. Nanoengineering of methylene blue loaded silica encapsulated magnetite nanospheres and nanocapsules for photodynamic therapy

    Energy Technology Data Exchange (ETDEWEB)

    Andhariya, Nidhi [Bhavnagar University, Department of Physics (India); Chudasama, Bhupendra, E-mail: bnchudasama@gmail.com [Thapar University, School of Physics and Materials Science (India); Mehta, R. V. [Bhavnagar University, Department of Physics (India); Upadhyay, R. V. [Charotar University of Science and Technology, P.D. Patel Institute of Applied Sciences (India)

    2011-09-15

    Core-shell nanostructures have emerged as an important class of functional materials with potential applications in diverse fields, especially in health sciences. In this article, nanoengineering of novel magnetic colloidal dispersion containing surface modifiable silica with a core of single domain magnetite nanoparticles loaded with photosensitizer (PS) drug 'Methylene blue' (MB) has been described. Magnetite core is produced by the well-established chemical coprecipitation technique and silica shell is formed over it by the modified hydrolysis and condensation of TEOS (tetraethyl orthosilicate). Conditions for reaction kinetics have been established to tailor the core-shell structures in the form of nanospheres and nanocapsules. MB is loaded into the nanostructures by demethylation reaction. The major conclusion drawn from this study is that the synthesis route yields stable, non-aggregated MB loaded superparamagnetic magnetite-silica nanostructures with tailored morphology, tunable loading, and excellent magnetic properties.

  1. Cascade enzymatic catalysis in poly(acrylic acid) brushes-nanospherical silica for glucose detection.

    Science.gov (United States)

    Zhao, Yan; Wang, Ying; Zhang, Xiaobin; Kong, Rongmei; Xia, Lian; Qu, Fengli

    2016-08-01

    The ultrasensitive monitoring of glucose with a fast and accurate method is significant in potential therapeutics and optimizes protein biosynthesis. Incorporation of enzyme into matrix is considered as promising candidates for constructing highly sensitive glucose-responsive systems. In this study, three-dimensional poly(acrylic acid) brushes-nanospherical silica (PAA-nano silica) with high amplification capability and stability were used to covalently immobilize bienzymes for cascade enzymatic catalysis. The major advantages of PAA-nano silica-bienzyme co-incorporation is that the enzymes are proximity distribution, and such close confinement both minimized the diffusion of intermediates among the enzymes in the consecutive reaction and improve the utilization efficiency of enzymes, thereby enhancing the overall reaction efficiency and specificity. Thus, this present bienzymatic biosensor shows robust signal amplification and ultrasensitivity of glucose-responsive properties with a detection limit of 0.04μM.

  2. Comparative DNA isolation behaviours of silica and polymer based sorbents in batch fashion: monodisperse silica microspheres with bimodal pore size distribution as a new sorbent for DNA isolation.

    Science.gov (United States)

    Günal, Gülçin; Kip, Çiğdem; Eda Öğüt, S; İlhan, Hasan; Kibar, Güneş; Tuncel, Ali

    2017-03-22

    Monodisperse silica microspheres with bimodal pore-size distribution were proposed as a high performance sorbent for DNA isolation in batch fashion under equilibrium conditions. The proposed sorbent including both macroporous and mesoporous compartments was synthesized 5.1 μm in-size, by a "staged shape templated hydrolysis and condensation method". Hydrophilic polymer based sorbents were also obtained in the form of monodisperse-macroporous microspheres ca 5.5 μm in size, with different functionalities, by a developed "multi-stage microsuspension copolymerization" technique. The batch DNA isolation performance of proposed material was comparatively investigated using polymer based sorbents with similar morphologies. Among all sorbents tried, the best DNA isolation performance was achieved with the monodisperse silica microspheres with bimodal pore size distribution. The collocation of interconnected mesoporous and macroporous compartments within the monodisperse silica microspheres provided a high surface area and reduced the intraparticular mass transfer resistance and made easier both the adsorption and desorption of DNA. Among the polymer based sorbents, higher DNA isolation yields were achieved with the monodisperse-macroporous polymer microspheres carrying trimethoxysilyl and quaternary ammonium functionalities. However, batch DNA isolation performances of polymer based sorbents were significantly lower with respect to the silica microspheres.

  3. Arrays of Hollow Silica Half-Nanospheres Via the Breath Figure Approach

    KAUST Repository

    Gao, Yangqin

    2015-04-21

    Breath figures (BFs) are patterns of liquid droplets that usually form upon condensation on a cold surface. Earlier work has shown that BFs can be used to produce continuous films of porous honeycomb-structured patterns on various types of materials, paving the path to a number of important applications such as the manufacturing of highly ordered nano- and micron-sized templates, micro lenses, and superhydrophobic coatings. It is worth noting, however, that few new findings have been reported in this area in recent years, limiting pursuits of novel architectures and key applications. In this report, an alternative method is described by which arrays of hollow silica half-nanospheres can be produced via BF templates. In the present method, a chemical vapor deposition (CVD) protocol performed while the BF is formed on a glass substrate yields a nanostructured pattern of silica half-spheres, which size (100-700 nm) and density across the glass surface vary with substrate modification and with the relative rates of water condensation and hydrolysis from silica precursors (a process carried out at room temperature). This method of forming arrays of hollow half-nanospheres via the BF approach may be applicable to various other oxides and a broad range of substrates including large-area flexible plastics. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Gold Nanoparticles Supported on Fibrous Silica Nanospheres (KCC-1) as Efficient Heterogeneous Catalysts for CO Oxidation

    KAUST Repository

    Qureshi, Ziyauddin S.

    2016-04-13

    Gold nanoparticles (Au NPs) of different sizes were supported on fibrous silica nanospheres (KCC-1) by various methods. The size and the location of the Au NPs on the support were found to depend on the preparation method. The KCC-1-supported Au NPs were thoroughly characterized by using HR-TEM, XRD, X-ray photoelectron spectroscopy, UV, and Brunauer-Emmett-Teller surface area measurements and were applied in catalysis for the oxidation of CO. The catalytic performance is discussed in relation to the morphological properties of KCC-1. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Monodisperse metal nanoparticle catalysts on silica mesoporous supports: synthesis, characterizations, and catalytic reactions

    Energy Technology Data Exchange (ETDEWEB)

    Somorjai, G.A.

    2009-09-14

    The design of high performance catalyst achieving near 100% product selectivity at maximum activity is one of the most important goals in the modern catalytic science research. To this end, the preparation of model catalysts whose catalytic performances can be predicted in a systematic and rational manner is of significant importance, which thereby allows understanding of the molecular ingredients affecting the catalytic performances. We have designed novel 3-dimensional (3D) high surface area model catalysts by the integration of colloidal metal nanoparticles and mesoporous silica supports. Monodisperse colloidal metal NPs with controllable size and shape were synthesized using dendrimers, polymers, or surfactants as the surface stabilizers. The size of Pt, and Rh nanoparticles can be varied from sub 1 nm to 15 nm, while the shape of Pt can be controlled to cube, cuboctahedron, and octahedron. The 3D model catalysts were generated by the incorporation of metal nanoparticles into the pores of mesoporous silica supports via two methods: capillary inclusion (CI) and nanoparticle encapsulation (NE). The former method relies on the sonication-induced inclusion of metal nanoparticles into the pores of mesoporous silica, whereas the latter is performed by the encapsulation of metal nanoparticles during the hydrothermal synthesis of mesoporous silica. The 3D model catalysts were comprehensively characterized by a variety of physical and chemical methods. These catalysts were found to show structure sensitivity in hydrocarbon conversion reactions. The Pt NPs supported on mesoporous SBA-15 silica (Pt/SBA-15) displayed significant particle size sensitivity in ethane hydrogenolysis over the size range of 1-7 nm. The Pt/SBA-15 catalysts also exhibited particle size dependent product selectivity in cyclohexene hydrogenation, crotonaldehyde hydrogenation, and pyrrole hydrogenation. The Rh loaded SBA-15 silica catalyst showed structure sensitivity in CO oxidation reaction. In

  6. The synthesis of clusters of iron oxides in mesopores of monodisperse spherical silica particles

    Science.gov (United States)

    Stovpiaga, E. Yu.; Eurov, D. A.; Kurdyukov, D. A.; Smirnov, A. N.; Yagovkina, M. A.; Grigorev, V. Yu.; Romanov, V. V.; Yakovlev, D. R.; Golubev, V. G.

    2017-08-01

    The method of obtaining nanoclusters α-Fe2O3 in the pores of monodisperse spherical particles of mesoporous silica ( mSiO2) by a single impregnation of the pores with a melt of crystalline hydrate of ferric nitrate and its subsequent thermal destruction has been proposed. Fe3O4 nanoclusters are synthesized from α-Fe2O3 in the pores by reducing in thermodynamically equilibrium conditions. Then particles containing Fe3O4 were annealed in oxygen for the conversion of Fe3O4 back to α-Fe2O3. In the result, the particles with the structure of the core-shell mSiO2/Fe3O4@ mSiO2/α-Fe2O3 are obtained. The composition and structure of synthesized materials as well as the field dependence of the magnetic moment on the magnetic field strength have been investigated.

  7. Preparation of hollow silica nanospheres in O/W microemulsion system by hydrothermal temperature changes

    Science.gov (United States)

    Wang, Dandan; Li, Xiuyan; Liu, Zuohua; Shi, Xue; Zhou, Guowei

    2017-01-01

    Hollow silica nanospheres with wrinkled or smooth surfaces were successfully fabricated through a hydrothermal method. In this method, oil-in-water microemulsion (composed of cyclohexane, water, ethanol, and cetyltrimethylammonium bromide), and polyvinylpyrrolidone were utilized as template and capping agent, respectively. In such a facile synthesis, we can well realize the morphological transformation of spheres with radially oriented mesochannels to hollow structures of silica nanoparticle only by regulating the hydrothermal temperature from 100 °C to 200 °C. Synthesized samples with different mesostructures were then used as supports to immobilize Candida rugosa lipase (CRL). The immobilized CRL was employed as a new biocatalyst for biodiesel production through the esterification of heptanoic acid with ethanol. The conversion ratio of heptanoic acid with ethanol catalyzed by the immobilized CRL was also evaluated. Results of this study suggest that the prepared samples have potential applications in biocatalysis.

  8. Silica micro/nanospheres for theranostics: from bimodal MRI and fluorescent imaging probes to cancer therapy

    Directory of Open Access Journals (Sweden)

    Shanka Walia

    2015-02-01

    Full Text Available Nano-theranostics offer remarkable potential for future biomedical technology with simultaneous applications for diagnosis and therapy of disease sites. Through smart and careful chemical modifications of the nanoparticle surface, these can be converted to multifunctional tiny objects which in turn can be used as vehicle for delivering multimodal imaging agents and therapeutic material to specific target sites in vivo. In this sense, bimodal imaging probes that simultaneously enable magnetic resonance imaging and fluorescence imaging have gained tremendous attention because disease sites can be characterized quick and precisely through synergistic multimodal imaging. But such hybrid nanocomposite materials have limitations such as low chemical stability (magnetic component and harsh cytotoxic effects (fluorescent component and, hence, require a biocompatible protecting agent. Silica micro/nanospheres have shown promise as protecting agent due to the high stability and low toxicity. This review will cover a full description of MRI-active and fluorescent multifunctional silica micro/nanospheres including the design of the probe, different characterization methods and their application in imaging and treatment in cancer.

  9. Hybrid thin films derived from UV-curable acrylate-modified waterborne polyurethane and monodispersed colloidal silica

    Directory of Open Access Journals (Sweden)

    C. H. Yang

    2012-01-01

    Full Text Available Hybrid thin films containing nano-sized inorganic domains were synthesized from UV-curable acrylate-modified waterborne polyurethane (WPU-AC and monodispersed colloidal silica with coupling agent. The coupling agent, 3-(trimethoxysilylpropyl methacrylate (MSMA, was bonded onto colloidal silica first, and then mixed with WPU-AC to form a precursor solution. This precursor was spin coated, dried and UV-cured to generate the hybrid films. The silica content in the hybrid thin films was varied from 0 to 30 wt%. Experimental results showed the aggregation of silica particles in the hybrid films. Thus, the silica domain in the hybrid films was varied from 30 to 50 nm by the different ratios of MSMAsilica to WPU-AC. The prepared hybrid films from the crosslinked WPU-AC/MSMA-silica showed much better thermal stability and mechanical properties than pure WPU-AC.

  10. Synthesis and characterization of stable monodisperse silica nanoparticle sols for in vitro cytotoxicity testing.

    Science.gov (United States)

    Thomassen, Leen C J; Aerts, Alexander; Rabolli, Virginie; Lison, Dominique; Gonzalez, Laetitia; Kirsch-Volders, Micheline; Napierska, Dorota; Hoet, Peter H; Kirschhock, Christine E A; Martens, Johan A

    2010-01-05

    For the investigation of the interaction of nanoparticles with biomolecules, cells, organs, and animal models there is a need for well-characterized nanoparticle suspensions. In this paper we report the preparation of monodisperse dense amorphous silica nanoparticles (SNP) suspended in physiological media that are sterile and sufficiently stable against aggregation. SNP sols with various particle sizes (2-335 nm) were prepared via base-catalyzed hydrolysis and polymerization of tetraethyl orthosilicate under sterile conditions using either ammonia (Stober process (1) ) or lysine catalyst (Lys-Sil process (2) ). The series was complemented with commercial silica sols (Ludox). Silica nanoparticle suspensions were purified by dialysis and dispersed without using any dispersing agent into cell culture media (Dulbecco's Modified Eagle's medium) containing antibiotics. Particle sizes were determined by dynamic light scattering. SNP morphology, surface area, and porosity were characterized using electron microscopy and nitrogen adsorption. The SNP sols in cell culture medium were stable for several days. The catalytic activity of the SNP in the conversion of hydrogen peroxide into hydroxyl radicals was investigated using electron paramagnetic resonance. The catalytic activity per square meter of exposed silica surface area was found to be independent of particle size and preparation method. Using this unique series of nanoparticle suspensions, the relationship between cytotoxicity and particle size was investigated using human endothelial and mouse monocyte-macrophage cells. The cytotoxicity of the SNP was strongly dependent on particle size and cell type. This unique methodology and the collection of well-characterized SNP will be useful for further in vitro studies exploring the physicochemical determinants of nanoparticle toxicity.

  11. Templated synthesis of monodisperse mesoporous maghemite/silica microspheres for magnetic separation of genomic DNA

    Science.gov (United States)

    Chen, Feng; Shi, Ruobing; Xue, Yun; Chen, Lei; Wan, Qian-Hong

    2010-08-01

    A novel method is described for the preparation of superparamagnetic mesoporous maghemite (γ-Fe 2O 3)/silica (SiO 2) composite microspheres to allow rapid magnetic separation of DNA from biological samples. With magnetite (Fe 3O 4) and silica nanoparticles as starting materials, such microspheres were synthesized by the following two consecutive steps: (1) formation of monodispersed organic/inorganic hybrid microspheres through urea-formaldedyde (UF) polymerization and (2) removal of the organic template and phase transformation of Fe 3O 4 to γ-Fe 2O 3 by calcination at elevated temperatures. The as-synthesized particles obtained by heating at temperature 300 °C feature spherical shape and uniform particle size ( dparticle=1.72 μm), high saturation magnetization ( Ms=17.22 emu/g), superparamagnetism ( Mr/ Ms=0.023), high surface area ( SBET=240 m 2/g), and mesoporosity ( dpore=6.62 nm). The composite microsphere consists of interlocked amorphous SiO 2 nanoparticles, in which cubic γ-Fe 2O 3 nanocrystals are homogeneously dispersed and thermally stable against γ- to α-phase transformation at temperatures up to 600 °C. With the exposed iron oxide nanoparticles coated with a thin layer of silica shell, the magnetic microspheres were used as a solid-phase adsorbent for rapid extraction of genomic DNA from plant samples. The results show that the DNA templates isolated from pea and green pepper displayed single bands with molecular weights greater than 8 kb and A260/ A280 values of 1.60-1.72. The PCR amplification of a fragment encoding the endogenous chloroplast ndhB gene confirmed that the DNA templates obtained were inhibitor-free and amenable to sensitive amplification-based DNA technologies.

  12. Layered double hydroxides as carriers for quantum dots@silica nanospheres

    Science.gov (United States)

    Stoica, Georgiana; Castelló Serrano, Iván.; Palomares, Emilio

    2013-02-01

    Quantum dot-hydrotalcite layered nanoplatforms were successfully prepared following a one-pot synthesis. The process is very fast and a priori delamination of hydrotalcite is not a prerequisite for the intercalation of quantum dots. The novel materials were extensively characterized by X-ray diffraction, thermogravimetry, infrared spectroscopy, transmission electron microscopy, true color fluorescence microscopy, photoluminescence, and nitrogen adsorption. The quantum dot-hydrotalcite nanomaterials display extremely high stability in mimicking physiological media such as saline serum (pH 5.5) and PBS (pH 7.2). Yet, quantum dot release from the solid structure is noted. In order to prevent the leaking of quantum dots we have developed a novel strategy which consists on using tailor made double layered hydrotalcites as protecting shells for quantum dots embedded into silica nanospheres without changing either the materials or the optical properties.

  13. Hydrophobic core/hydrophilic shell structured mesoporous silica nanospheres: enhanced adsorption of organic compounds from water.

    Science.gov (United States)

    Li, Shuru; Jiao, Xuan; Yang, Hengquan

    2013-01-29

    Inspired by the structure features of micelle, we attempt to synthesize a novel functionalized mesoporous silica nanosphere consisting of a hydrophobic core and a hydrophilic shell. The obtained solid materials were structurally confirmed by N(2) sorption, X-ray diffraction (XRD), and transmission electron microscopy (TEM). Their compositions were characterized by Fourier transfer infrared spectroscopy (FT-IR), solid state NMR, X-ray photoelectron spectroscopy (XPS), and elemental analysis. Its fundamental properties such as dispersibility in water or organic phase, wettability, and adsorption ability toward hydrophobic organics in water were investigated. It was revealed that these important properties could be facilely adjusted through varying structure and composition. In particular, these materials showed much better adsorption ability toward hydrophobic organic molecules in water than conventional monofunctionalized mesoporous materials, owing to possessing the hydrophobic/hydrophilic domain-segregated and hierarchically functionalized mesoporous structures. The intriguing properties would make mesoporous materials more accessible to many important applications, especially in aqueous systems.

  14. Templated synthesis of monodisperse mesoporous maghemite/silica microspheres for magnetic separation of genomic DNA

    Energy Technology Data Exchange (ETDEWEB)

    Chen Feng; Shi Ruobing; Xue Yun; Chen Lei [School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072 (China); Wan Qianhong, E-mail: qhwan@tju.edu.c [School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072 (China)

    2010-08-15

    A novel method is described for the preparation of superparamagnetic mesoporous maghemite (gamma-Fe{sub 2}O{sub 3})/silica (SiO{sub 2}) composite microspheres to allow rapid magnetic separation of DNA from biological samples. With magnetite (Fe{sub 3}O{sub 4}) and silica nanoparticles as starting materials, such microspheres were synthesized by the following two consecutive steps: (1) formation of monodispersed organic/inorganic hybrid microspheres through urea-formaldedyde (UF) polymerization and (2) removal of the organic template and phase transformation of Fe{sub 3}O{sub 4} to gamma-Fe{sub 2}O{sub 3} by calcination at elevated temperatures. The as-synthesized particles obtained by heating at temperature 300 deg. C feature spherical shape and uniform particle size (d{sub particle}=1.72 mum), high saturation magnetization (M{sub s}=17.22 emu/g), superparamagnetism (M{sub r}/M{sub s}=0.023), high surface area (S{sub BET}=240 m{sup 2}/g), and mesoporosity (d{sub pore}=6.62 nm). The composite microsphere consists of interlocked amorphous SiO{sub 2} nanoparticles, in which cubic gamma-Fe{sub 2}O{sub 3} nanocrystals are homogeneously dispersed and thermally stable against gamma- to alpha-phase transformation at temperatures up to 600 deg. C. With the exposed iron oxide nanoparticles coated with a thin layer of silica shell, the magnetic microspheres were used as a solid-phase adsorbent for rapid extraction of genomic DNA from plant samples. The results show that the DNA templates isolated from pea and green pepper displayed single bands with molecular weights greater than 8 kb and A{sub 260}/A{sub 280} values of 1.60-1.72. The PCR amplification of a fragment encoding the endogenous chloroplast ndhB gene confirmed that the DNA templates obtained were inhibitor-free and amenable to sensitive amplification-based DNA technologies.

  15. Mesoporous hollow nanospheres consisting of carbon coated silica nanoparticles for robust lithium-ion battery anodes

    Science.gov (United States)

    An, Weili; Fu, Jijiang; Su, Jianjun; Wang, Lei; Peng, Xiang; Wu, Kai; Chen, Qiuyun; Bi, Yajun; Gao, Biao; Zhang, Xuming

    2017-03-01

    SiO2 as lithium ion batteries (LIBs) anode has drawn considerable attentions because of its low cost, high theoretical specific capacity and low discharge potentials but been limited by its low conductivity and electrochemical kinetics, resulting in obvious capacity decay and poor rate performance. Herein, we developed a simple approach to synthesize mesoporous hollow nanosphere (MHSiO2@C) assembled by conformal carbon coating tiny silica nanoparticles through chemical polymerization of dopamine inside the shell of MHSiO2. The continuous carbon can conformally coat on the surface of all primary SiO2 nanoparticles in the shell, which not only enhances the conductivity but also improves the structural stability of the MHSiO2. Compared to raw MHSiO2 and non-conformal carbon coated MHSiO2, the MHSiO2@C demonstrate a high reversible capacity of 440.7 mA h g-1 at a current density of 0.5 A g-1 after 500 cycles and excellent rate performance due to synergetic effect of special structure of MHSiO2 and carbon conformal coating on each silica nanoparticle. Such a special structure will be a promising platform for LIBs. Significantly, this paper offers a direct evidence to prove the advantage of conformal carbon coating and provides consequentially guide in improving the energy storage performance of low-conductivity oxide based electrode materials.

  16. High Ionic Conductivity of Composite Solid Polymer Electrolyte via In Situ Synthesis of Monodispersed SiO2 Nanospheres in Poly(ethylene oxide).

    Science.gov (United States)

    Lin, Dingchang; Liu, Wei; Liu, Yayuan; Lee, Hye Ryoung; Hsu, Po-Chun; Liu, Kai; Cui, Yi

    2016-01-13

    High ionic conductivity solid polymer electrolyte (SPE) has long been desired for the next generation high energy and safe rechargeable lithium batteries. Among all of the SPEs, composite polymer electrolyte (CPE) with ceramic fillers has garnered great interest due to the enhancement of ionic conductivity. However, the high degree of polymer crystallinity, agglomeration of ceramic fillers, and weak polymer-ceramic interaction limit the further improvement of ionic conductivity. Different from the existing methods of blending preformed ceramic particles with polymers, here we introduce an in situ synthesis of ceramic filler particles in polymer electrolyte. Much stronger chemical/mechanical interactions between monodispersed 12 nm diameter SiO2 nanospheres and poly(ethylene oxide) (PEO) chains were produced by in situ hydrolysis, which significantly suppresses the crystallization of PEO and thus facilitates polymer segmental motion for ionic conduction. In addition, an improved degree of LiClO4 dissociation can also be achieved. All of these lead to good ionic conductivity (1.2 × 10(-3) S cm(-1) at 60 °C, 4.4 × 10(-5) S cm(-1) at 30 °C). At the same time, largely extended electrochemical stability window up to 5.5 V can be observed. We further demonstrated all-solid-state lithium batteries showing excellent rate capability as well as good cycling performance.

  17. In Situ Monitoring of the Generation of Monodisperse Silica Particles during the Hydrolysis of Tetraethyl Orthosilicate with Piezoelectric Quartz Crystal Impedance Analyzer

    Institute of Scientific and Technical Information of China (English)

    姚守拙; 张友玉; 谢青季

    2003-01-01

    The piezoelectric quartz crystal(PQC)impedance analyzer was used to monitor in situ the generation of monodisperse silica particles during the hydrolysis of tetraethyl orthosilicate (TEOS) and their adsorption onto and Au electrode in alcohol solutions containing water(6-15mol/L)and ammonia(0.2-2.0 mol/L).The equivalent circuit parameters,the resonance frequencies and the half-peak width values of the conductance spectra of the PQC resonance were obtained.The resonant frequency decreased notably while the motional resistance changed very slightly(within 1Ω during the hydrolysis reaction,suggesting that the mass effect dominated the adsorption of generated monodisperse silica particles on the gold electrode in this system.Changes in f0 indicated that the ammonia concentration affected the hydrolytic reaction obviously,and the influence of water concentration on the reaction was small while the water was significantly excessive.Kinetics of monodisperse silica particle adsorption occurring at the electrode i solution interface was analyzed using a first-order reaction scheme.In addition,the electrolyte-induced precipitation of the monodisperse silica of adsorbed particles per area and the converge of monodisperse silica particles were obtained from scanning electron nicroscope(SEM)observations.

  18. Highly uniform and monodisperse carbon nanospheres enriched with cobalt-nitrogen active sites as a potential oxygen reduction electrocatalyst

    Science.gov (United States)

    Wan, Xing; Wang, Hongjuan; Yu, Hao; Peng, Feng

    2017-04-01

    Uniform cobalt and nitrogen co-doped carbon nanospheres (CoN-CNS) with high specific surface area (865 m2 g-1) have been prepared by a simple but efficient method. The prepared CoN-CNS catalyst exhibits outstanding catalytic performance for the oxygen reduction reaction (ORR) in both alkaline and acidic electrolytes. In alkaline electrolyte, the prepared CoN-CNS has more positive half-wave potential and larger kinetic current density than commercial Pt/C. In acidic electrolyte, CoN-CNS also shows good ORR activity with high electron transfer number, its onset and half-wave potentials are all close to those of commercial carbon supported platinum catalyst (Pt/C). CoN-CNS catalyst shows more superior stability and higher methanol-tolerance than commercial Pt/C both in alkaline and in acidic electrolytes. The potassium thiocyanate-poisoning test further confirms that the cobalt-nitrogen active sites exist in CoN-CNS, which are dominating to endow high ORR catalytic activity in acidic electrolyte. This study develops a new method to prepare non-precious metal catalyst with excellent ORR performances for direct methanol fuel cells.

  19. Synthesis of hollow silica nanosphere with high accessible surface area and their hybridization with carbon matrix for drastic enhancement of electrochemical property

    Energy Technology Data Exchange (ETDEWEB)

    Alam, Mohammad Mydul; Yamahana, Haruki [Department of Chemistry, Faculty of Science and Engineering, Saga University, 1 Honjo-machi, Saga 840-8502 (Japan); Bastakoti, Bishnu Prasad [World Premier International (WPI) Research Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science - NIMS, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); Luitel, Hom Nath; Zhao, Wenwen [Department of Chemistry, Faculty of Science and Engineering, Saga University, 1 Honjo-machi, Saga 840-8502 (Japan); Yamauchi, Yusuke [World Premier International (WPI) Research Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science - NIMS, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); Department of Nanoscience and Nanoengineering, Faculty of Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555 (Japan); Watari, Takanori; Noguchi, Hideyuki [Department of Chemistry, Faculty of Science and Engineering, Saga University, 1 Honjo-machi, Saga 840-8502 (Japan); Nakashima, Kenichi, E-mail: nakashik@cc.saga-u.ac.jp [Department of Chemistry, Faculty of Science and Engineering, Saga University, 1 Honjo-machi, Saga 840-8502 (Japan)

    2014-09-30

    Highlights: • Hollow silica nanosphere with large void space and high surface area is synthesized. • Carbon was doped into silica layer through glucose solution and resulting carbon/silica composite drastically enhanced electrochemical property. • Combination of core–shell–corona micelle template and doping method could be a new platform for developing functional materials. - Abstract: Hollow silica nanospheres with high accessible surface area have been synthesized by using core–shell–corona polymeric micelle of poly (styrene-b-2-vinyle pyridine-b-ethylene oxide) (PS45k-PVP26k-PEO82k) as a template. The size of the template polymeric micelle depends on the pH of the solution, i.e. ≈100 nm at pH 7 whereas ≈300 nm at pH 4. The enlarged size of the micelle is possibly due to the protonation of the PVP block, which also serves as reaction sites for silica precursor. The size of the obtained silica nanosphere measured with transmission electron microscope (TEM) is around ≈70 nm and shell thickness is ≈20 nm. Fourier transformed infrared spectroscopy (FTIR) data confirms that the polymer template is completely removed during calcination. Conductive carbon is doped into the silica nanosphere through glucose solution followed by hydrothermal treatment and pyrolysis. It is found that the electrochemical performance and stability of the silica nanosphere is dramatically enhanced after carbon doping. The combined strategy of the core–shell–corona micelle as template and carbon doping could represent a new platform for the researchers to develop functional nanomaterials.

  20. Epithelial cell biocompatibility of silica nanospheres for contrast-enhanced ultrasound molecular imaging

    Energy Technology Data Exchange (ETDEWEB)

    Chiriaco, Fernanda; Conversano, Francesco; Soloperto, Giulia; Casciaro, Ernesto [Institute of Clinical Physiology, Bioengineering Division, National Research Council (Italy); Ragusa, Andrea [National Nanotechnology Laboratory of CNR-NANO (Italy); Sbenaglia, Enzo Antonio; Dipaola, Lucia [Institute of Clinical Physiology, Bioengineering Division, National Research Council (Italy); Casciaro, Sergio, E-mail: sergio.casciaro@cnr.it [Istituto di Fisiologia Clinica (CNR-IFC) c/o Campus Universitario Ecotekne, Consiglio Nazionale delle Ricerche (Italy)

    2013-07-15

    Nanosized particles are receiving increasing attention as future contrast agents (CAs) for ultrasound (US) molecular imaging, possibly decorated on its surface with biological recognition agents for targeted delivery and deposition of therapeutics. In particular, silica nanospheres (SiNSs) have been demonstrated to be feasible in terms of contrast enhancement on conventional US systems. In this work, we evaluated the cytotoxicity of SiNSs on breast cancer (MCF-7) and HeLa (cervical cancer) cells employing NSs with sizes ranging from 160 to 330 nm and concentration range of 1.5-5 mg/mL. Cell viability was evaluated in terms of size, dose and time dependence, performing the MTT reduction assay with coated and uncoated SiNSs. Whereas uncoated SiNSs caused a variable significant decrease in cell viability on both cell lines mainly depending on size and exposure time, PEGylated SiNSs (SiNSs-PEG) exhibit a high level of biocompatibility. In fact, after 72-h incubation, viability of both cell types was above the cutoff value of 70 % at concentration up to 5 mg/mL. We also investigated the acoustical behavior of coated and uncoated SiNSs within conventional diagnostic US fields in order to determine a suitable configuration, in terms of particle size and concentration, for their employment as targetable CAs. Our results indicate that the employment of SiNSs with diameters around 240 nm assures the most effective contrast enhancement even at the lowest tested concentration, coupled with the possibility of targeting all tumor tissues, being the SiNSs still in a size range where reticuloendothelial system trapping effect is relatively low.

  1. Enhanced Performance of Mg0.1Zn0.9O UV Photodetectors Using Photoelectrochemical Treatment and Silica Nanospheres

    Directory of Open Access Journals (Sweden)

    Hsin-Ying Lee

    2014-01-01

    Full Text Available The Mg0.1Zn0.9O films were grown using atomic layer deposition (ALD system and applied to metal-semiconductor-metal ultraviolet photodetectors (MSM-UPDs as an active layer. To suppress the dangling bonds on the Mg0.1Zn0.9O surface, the photoelectrochemical (PEC treatment was used to passivate the Mg0.1Zn0.9O surface, which could reduce the dark current of the MSM-UPDs about one order. Beside, to increase more incident light into the Mg0.1Zn0.9O active layer of the MSM-UPDs, the 500-nm-diameter silica nanospheres were spin-coated on the Mg0.1Zn0.9O active layer to improve the antireflection capability at the wavelength of 340 nm. The reflectivity of the Mg0.1Zn0.9O films with silica nanospheres antireflection layer decreased about 7.0% in comparison with the Mg0.1Zn0.9O films without silica nanospheres. The photocurrent and UV-visible ratio of the passivated Mg0.1Zn0.9O MSM-UPDs with antireflection layer were enhanced to 5.85 μA and 1.44×104, respectively, at the bias voltage of 5 V. Moreover, the noise equivalent power and the specific detectivity of the passivated Mg0.1Zn0.9O MSM-UPDs with antireflection layer were decreased to 2.60×10-13 W and increased to 1.21×1012 cmHz1/2W−1, respectively, at the bias voltage of 5 V. According to the above mentions, the PEC treatment and silica nanospheres antireflection layer could effectively enhance the performance of Mg0.1Zn0.9O MSM-UPDs.

  2. Fabrication of monodisperse hollow silica spheres and effect on water vapor permeability of polyacrylate membrane.

    Science.gov (United States)

    Bao, Yan; Yang, Yongqiang; Ma, Jianzhong

    2013-10-01

    Polystyrene/silica core-shell spheres were fabricated using polystyrene as templates by hydrolysis and condensation of tetraethyl orthosilicate through a sol-gel process, in which polystyrene was synthesized by emulsion polymerization. Then, hollow silica spheres were obtained after selective removal of the organic polystyrene core from the polystyrene/silica core-shell spheres by tetrahydrofuran etching. The effect of hollow silica spheres on water vapor permeability, mechanical property, and water uptake of polyacrylate membrane were investigated. The microstructure analysis shows that the mean size and wall thickness of hollow silica spheres are 170 nm and 20 nm, respectively. The silica shells consist of amorphous silica seed assembly with a broad size distribution, which roughen the surfaces of hollow silica spheres greatly. The specific surface area of hollow silica spheres is bigger than that of polystyrene/silica core-shell spheres. Hollow silica spheres can significantly improve water vapor permeability of polyacrylate membrane, but lead to the reduction in mechanical property.

  3. Fabrication of and drug delivery by an upconversion emission nanocomposite with monodisperse LaF3:Yb,Er core / mesoporous silica shell structure

    NARCIS (Netherlands)

    Yang, Y.; Qu, Y.; Zhao, J.; Zeng, Q.; Ran, Y.; Zhang, Q.; Kong, X.; Zhang, H.

    2010-01-01

    Monodisperse, uniform, encapsulated mesoporous silicananocomposites with a LaF3:Yb,Er core and a mesoporous silica shell structure, which still exhibit green upconversion photoluminescence (PL) under 980 nm irradiation, have been successfully synthesized and investigated as potential drug delivery s

  4. "Hydro-metathesis" of olefins: A catalytic reaction using a bifunctional single-site tantalum hydride catalyst supported on fibrous silica (KCC-1) nanospheres

    KAUST Repository

    Polshettiwar, Vivek

    2011-02-18

    Tantalizing hydrocarbons: Tantalum hydride supported on fibrous silica nanospheres (KCC-1) catalyzes, in the presence of hydrogen, the direct conversion of olefins into alkanes that have higher and lower numbers of carbon atoms (see scheme). This catalyst shows remarkable catalytic activity and stability, with excellent potential of regeneration. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Enhancement of Alkaline Protease Activity and Stability via Covalent Immobilization onto Hollow Core-Mesoporous Shell Silica Nanospheres

    Directory of Open Access Journals (Sweden)

    Abdelnasser Salah Shebl Ibrahim

    2016-01-01

    Full Text Available The stability and reusability of soluble enzymes are of major concerns, which limit their industrial applications. Herein, alkaline protease from Bacillus sp. NPST-AK15 was immobilized onto hollow core-mesoporous shell silica (HCMSS nanospheres. Subsequently, the properties of immobilized proteases were evaluated. Non-, ethane- and amino-functionalized HCMSS nanospheres were synthesized and characterized. NPST-AK15 was immobilized onto the synthesized nano-supports by physical and covalent immobilization approaches. However, protease immobilization by covalent attachment onto the activated HCMSS–NH2 nanospheres showed highest immobilization yield (75.6% and loading capacity (88.1 μg protein/mg carrier and was applied in the further studies. In comparison to free enzyme, the covalently immobilized protease exhibited a slight shift in the optimal pH from 10.5 to 11.0, respectively. The optimum temperature for catalytic activity of both free and immobilized enzyme was seen at 60 °C. However, while the free enzyme was completely inactivated when treated at 60 °C for 1 h the immobilized enzyme still retained 63.6% of its initial activity. The immobilized protease showed higher Vmax, kcat and kcat/Km, than soluble enzyme by 1.6-, 1.6- and 2.4-fold, respectively. In addition, the immobilized protease affinity to the substrate increased by about 1.5-fold. Furthermore, the enzyme stability in various organic solvents was significantly enhanced upon immobilization. Interestingly, the immobilized enzyme exhibited much higher stability in several commercial detergents including OMO, Tide, Ariel, Bonux and Xra by up to 5.2-fold. Finally, the immobilized protease maintained significant catalytic efficiency for twelve consecutive reaction cycles. These results suggest the effectiveness of the developed nanobiocatalyst as a candidate for detergent formulation and peptide synthesis in non-aqueous media.

  6. Enhancement of Alkaline Protease Activity and Stability via Covalent Immobilization onto Hollow Core-Mesoporous Shell Silica Nanospheres.

    Science.gov (United States)

    Ibrahim, Abdelnasser Salah Shebl; Al-Salamah, Ali A; El-Toni, Ahmed M; Almaary, Khalid S; El-Tayeb, Mohamed A; Elbadawi, Yahya B; Antranikian, Garabed

    2016-01-29

    The stability and reusability of soluble enzymes are of major concerns, which limit their industrial applications. Herein, alkaline protease from Bacillus sp. NPST-AK15 was immobilized onto hollow core-mesoporous shell silica (HCMSS) nanospheres. Subsequently, the properties of immobilized proteases were evaluated. Non-, ethane- and amino-functionalized HCMSS nanospheres were synthesized and characterized. NPST-AK15 was immobilized onto the synthesized nano-supports by physical and covalent immobilization approaches. However, protease immobilization by covalent attachment onto the activated HCMSS-NH₂ nanospheres showed highest immobilization yield (75.6%) and loading capacity (88.1 μg protein/mg carrier) and was applied in the further studies. In comparison to free enzyme, the covalently immobilized protease exhibited a slight shift in the optimal pH from 10.5 to 11.0, respectively. The optimum temperature for catalytic activity of both free and immobilized enzyme was seen at 60 °C. However, while the free enzyme was completely inactivated when treated at 60 °C for 1 h the immobilized enzyme still retained 63.6% of its initial activity. The immobilized protease showed higher V(max), k(cat) and k(cat)/K(m), than soluble enzyme by 1.6-, 1.6- and 2.4-fold, respectively. In addition, the immobilized protease affinity to the substrate increased by about 1.5-fold. Furthermore, the enzyme stability in various organic solvents was significantly enhanced upon immobilization. Interestingly, the immobilized enzyme exhibited much higher stability in several commercial detergents including OMO, Tide, Ariel, Bonux and Xra by up to 5.2-fold. Finally, the immobilized protease maintained significant catalytic efficiency for twelve consecutive reaction cycles. These results suggest the effectiveness of the developed nanobiocatalyst as a candidate for detergent formulation and peptide synthesis in non-aqueous media.

  7. Preparation and characterization of 1-naphthylacetic acid-silica conjugated nanospheres for enhancement of controlled-release performance

    Science.gov (United States)

    Ao, Mingming; Zhu, Yuncong; He, Shun; Li, Deguang; Li, Pingliang; Li, Jianqiang; Cao, Yongsong

    2013-01-01

    Chemical pesticides have been widely used to increase the yield and quality of agricultural products as they are efficient, effective, and easy to apply. However, the rapid degradation and low utilization ratio of conventional pesticides has led to environmental pollution and resource waste. Nano-sized controlled-release formulations (CRFs) can provide better penetration through the plant cuticle and deliver the active ingredients efficiently to the targeted tissue. In this paper we reported novel conjugated nanospheres derived from 1-naphthylacetic acid (NNA), 3-aminopropyltriethoxysilane (APTES) and tetraethyl orthosilicate and their application as a controlled-release plant growth regulator. The NNA and APTES conjugate was prepared through a covalent cross-linking reaction and subsequent hydrolyzation and polycondensation to synthesize NNA-silica nanospheres. The release data indicated that the release of NNA was by non-Fickian transport and increased as particle size decreased. It was also found that the acidity-alkalinity was enhanced and as the temperature increased, the release of the active ingredient was faster. The nanoconjugate displayed a better efficacy in promoting root formation than NNA technical. The present study provides a novel synthesis route for CRFs comprising a pesticide, with long-duration sustained-release performance and good environmental compatibility. This method may be extended to other pesticides that possess a carboxyl group.

  8. Contact electrification in aerosolized monodispersed silica microspheres quantified using laser based velocimetry

    DEFF Research Database (Denmark)

    Alois, Stefano; Merrison, Jonathan P.; Iversen, Jens Jacob

    2017-01-01

    The contact electrification of aerosolized micro particles has been studied using a novel technique involving laser velocimetry. This has allowed the simultaneous determination of size and electrical charge of individual silica microspheres (in the range 1 – 8 µm). Interestingly the particles...

  9. Controlled Microwave-Assisted Growth of Monodisperse of Silica Nanoparticles under Acid Catalysis (Postprint)

    Science.gov (United States)

    2012-11-26

    over conventional heating techniques because they deliver large amounts of controlled power quickly to small volumes of absorbing media, promoting...transition states, such as pentacoordinate and hexacoordinate silanes .25,38,39 Recently, a DFT study has postulated that the formation of stable silica

  10. Multilayer encapsulated mesoporous silica nanospheres as an oral sustained drug delivery system for the poorly water-soluble drug felodipine

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Liang [Department of Pharmaceutics, Shenyang Pharmaceutical University, P.O. Box 32, Liaoning Province, Shenyang 110016 (China); Sun, Hongrui [English Teaching Department, School of Basic Courses, Shenyang Pharmaceutical University, Wenhua Road 103, Shenyang 110016 (China); Zhao, Qinfu; Han, Ning; Bai, Ling; Wang, Ying; Jiang, Tongying [Department of Pharmaceutics, Shenyang Pharmaceutical University, P.O. Box 32, Liaoning Province, Shenyang 110016 (China); Wang, Siling, E-mail: silingwang@syphu.edu.cn [Department of Pharmaceutics, Shenyang Pharmaceutical University, P.O. Box 32, Liaoning Province, Shenyang 110016 (China)

    2015-02-01

    We used a combination of mesoporous silica nanospheres (MSN) and layer-by-layer (LBL) self-assembly technology to establish a new oral sustained drug delivery system for the poorly water-soluble drug felodipine. Firstly, the model drug was loaded into MSN, and then the loaded MSN were repeatedly encapsulated by chitosan (CHI) and acacia (ACA) via LBL self-assembly method. The structural features of the samples were studied using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and nitrogen adsorption. The encapsulating process was monitored by zeta-potential and surface tension measurements. The physical state of the drug in the samples was characterized by differential scanning calorimetry (DSC) and X-ray diffractometry (XRD). The influence of the multilayer with different number of layers on the drug release rate was studied using thermal gravimetric analysis (TGA) and surface tension measurement. The swelling effect and the structure changes of the multilayer were investigated to explore the relationship between the drug release behavior and the state of the multilayer under different pH conditions. The stability and mucosa adhesive ability of the prepared nanoparticles were also explored. After multilayer coating, the drug release rate was effectively controlled. The differences in drug release behavior under different pH conditions could be attributed to the different states of the multilayer. And the nanoparticles possessed good stability and strong mucosa adhesive ability. We believe that this combination offers a simple strategy for regulating the release rate of poorly water-soluble drugs and extends the pharmaceutical applications of inorganic materials and polymers. - Highlights: • A combination of inorganic and organic materials was applied. • Mesoporous silica nanospheres (MSN) were used as drug carriers. • Chitosan and acacia were encapsulated through layer-by-layer self-assembly. • The release rate of the poorly

  11. Solid-State Conversion Chemistry of Multicomponent Nanocrystals Cast in a Hollow Silica Nanosphere: Morphology-Controlled Syntheses of Hybrid Nanocrystals.

    Science.gov (United States)

    Kim, Yeon Jun; Choi, Jung Kyu; Lee, Dong-Gyu; Baek, Kyungjoon; Oh, Sang Ho; Lee, In Su

    2015-11-24

    During thermal transformation of multicomponent nanocrystals in a silica nanosphere, FeAuPd alloy nanocrystals migrate outward and thereby leave a cavity in the silica matrix. Oxidation then converts these nanocrystals back into phase-segregated hybrid nanocrystals, AuPd@Fe3O4, with various morphologies. The FeAuPd-to-AuPd@Fe3O4 transformation was cast by the in situ generated hollow silica mold. Therefore, the morphological parameters of the transformed AuPd@Fe3O4 are defined by the degree of migration of the FeAuPd in the hollow silica nanoshell. This hollow silica-cast nanocrystal conversion was studied to develop a solid state protocol that can be used to produce a range of hybrid nanocrystals and that allows for systematic and sophisticated control of the resulting morphologies.

  12. Synthesis and characterization of perm-selective SERS-active silica-coated gold nanospheres for the direct detection of small molecules

    Science.gov (United States)

    Pierre-Bolivar, Marie Carmelle Serviane

    Noble metal nanomaterials have numerous uses in plasmonic and surface enhanced Raman scattering (SERS) detection applications; however, upon the addition of analytes, nanomaterials often undergo uncontrolled aggregation which leads to inconsistent signal intensities. To overcome this limitation, the effect of gold nanosphere concentration, column purification, and surface chemistry functionalization using internally etched silica stabilization methods was investigated on SERS assays for small molecule detection. Nanostructure composition, size, shape, stability, surface chemistry, optical properties, and SERS-activity were monitored using localized surface plasmon resonance (LSPR or extinction) spectroscopy, transmission electron microscopy (TEM), and Raman spectroscopy. First, the behavior of citrate-stabilized gold nanospheres was monitored as a function of molecular surface coverage. Both extinction and SERS spectral intensities increased linearly below monolayer functionalization. Above this value, however, uncontrolled nanoparticle aggregation occurred and large but irreproducible SERS signal intensities were monitored. Next, gold nanoparticles were encapsulated with varying silica shell thicknesses and purified using traditional centrifugation steps and/or column chromatography. Relative to the traditionally purified (i.e. centrifuged) samples, the SERS responses from small molecules using the column purified nanoparticle samples followed a well-known SERS distance-dependence model. Thus, surface chemistry cannot form more than a 2 nm thick layer on gold nanospheres if SERS applications were targeted. To overcome these challenges, gold nanospheres encapsulated with a thick silica shell were made SERS-active by etching the internal silica layer near the metal surface. During the synthesis of these internally etched silica-coated gold nanospheres, the LSPR wavelength shift, a parameter related to the effective local refractive index near the gold core, was

  13. Silica-modified monodisperse hexagonal lanthanide nanocrystals: synthesis and biological properties.

    Science.gov (United States)

    Kostiv, U; Janoušková, O; Šlouf, M; Kotov, N; Engstová, H; Smolková, K; Ježek, P; Horák, D

    2015-11-21

    Oleic acid-stabilized hexagonal NaYF4:Yb(3+)/Er(3+) nanocrystals, emitting green and red luminescence, were prepared by the high-temperature co-precipitation of lanthanide chlorides. By varying the reaction time and the Ln(3+)/Na(+) ratio, the nanocrystal size can be controlled within the range 16-270 nm. The maximum upconversion quantum yield is achieved under 970 nm excitation. The reverse microemulsion technique using hydrolysis and condensation of tetraethoxysilane is a suitable method to coat the nanocrystal surface with a silica shell to make the particles dispersible and colloidally stable in aqueous media. During the subsequent functionalization, (3-aminopropyl)trimethoxysilane introduced amino groups onto the silica to enable future bioconjugation with the target molecules. All specimens were characterized by TEM microscopy, electron and X-ray diffraction, ATR FT-IR spectroscopy, and upconversion luminescence. Finally, in vitro cytotoxicity and intracellular nanoparticle uptake (using confocal microscopy) were determined with human cervical carcinoma HeLa and mRoGFP HeLa cells, respectively. From the investigated particles, amino-functionalized NaYF4:Yb(3+)/Er(3+) nanocrystals internalized into the cells most efficiently. The nanoparticles proved to be nontoxic at moderate concentrations, which is important when considering their prospective application in biolabeling and luminescence imaging of various cell types.

  14. Alginate encapsulated mesoporous silica nanospheres as a sustained drug delivery system for the poorly water-soluble drug indomethacin

    Directory of Open Access Journals (Sweden)

    Liang Hu

    2014-08-01

    Full Text Available We applied a combination of inorganic mesoporous silica material, frequently used as drug carriers, and a natural organic polymer alginate (ALG, to establish a sustained drug delivery system for the poorly water-soluble drug Indomethacin (IND. Mesoporous silica nanospheres (MSNs were synthesized using an organic template method and then functionalized with aminopropyl groups through postsynthesis. After drug loading into the pores of aninopropyl functionalized MSNs (AP-MSNs, IND loaded AP-MSNs (IND-AP-MSNs were encapsulated by ALG through the ionic interaction. The effects of surface chemical groups and ALG layer on IND release were systematically studied using scanning electron microscopy (SEM, transmission electron microscopy (TEM, nitrogen adsorption, zeta-potential analysis and TGA analysis. The surface structure and surface charge changes of the ALG encapsulated AP-MSNs (ALG-AP-MSNs were also investigated. The results showed that sustained release of IND from the designed drug delivery system was mainly due to the blockage effect from the coated ALG. We believe that this combination will help designing oral sustained drug delivery systems for poorly water-soluble drugs.

  15. Fabrication of Silica Nanospheres Coated Membranes: towards the Effective Separation of Oil-in-Water Emulsion in Extremely Acidic and Concentrated Salty Environments

    OpenAIRE

    Yuning Chen; Na Liu; Yingze Cao; Xin Lin; Liangxin Xu; Weifeng Zhang; Yen Wei; Lin Feng

    2016-01-01

    A superhydrophilic and underwater superoleophobic surface is fabricated by simply coating silica nanospheres onto a glass fiber membrane through a sol-gel process. Such membrane has a complex framework with micro and nano structures covering and presents a high efficiency (more than 98%) of oil-in-water emulsion separation under harsh environments including strong acidic and concentrated salty conditions. This membrane also possesses outstanding stability since no obvious decline in efficienc...

  16. A facile route to prepare hierarchical magnetic cobalt-silica hollow nanospheres with tunable shell thickness

    Energy Technology Data Exchange (ETDEWEB)

    Wang Jun, E-mail: wjnaf@ustc.edu; Xu Chuanhui; Yao Min; Chen Jie [NingBo University, Faculty of Science (China); Xu Gaojie [Ningbo Institute of Material Technology and Engineering (China)

    2010-05-15

    Magnetic nanoshells composed of close-packed cobalt-silica nanoparticles have been successfully fabricated on silica spheres. The synthesis is facile and no high pressure, high temperature, or other severe reaction conditions were required. TEM images showed that two batches of the hollow-structured products have a good spherical morphology with an average diameter of 380 and 550 nm, respectively. The surface area and magnetic properties of cobalt-silica nanoshells are measured. By varying the times of the precipitation procedure, the shell thickness is successfully controlled within the 5-30 nm range and each time of procedure might increase the thickness about 5 nm. It is expected that the in situ reaction method can be extended to the synthesis of other hollow metal spheres. The prepared microcapsule with controllable shell thickness and interspaces has the potential to be used for controlled release applications.

  17. Gadolinium(III)-Chelated Silica Nanospheres Integrating Chemotherapy and Photothermal Therapy for Cancer Treatment and Magnetic Resonance Imaging.

    Science.gov (United States)

    Cao, Mingjing; Wang, Pengyang; Kou, Yu; Wang, Jing; Liu, Jing; Li, Yanhui; Li, Jiayang; Wang, Liming; Chen, Chunying

    2015-11-18

    The combination of therapy and diagnosis has been emerging as a promising strategy for cancer treatment. To realize chemotherapy, photothermal therapy, and magnetic resonance imaging (MRI) in one system, we have synthesized a new magnetic nanoparticle (Gd@SiO2-DOX/ICG-PDC) integrating doxorubicin (DOX), indocyanine green (ICG), and gadolinium(III)-chelated silica nanospheres (Gd@SiO2) with a poly(diallyldimethylammonium chloride) (PDC) coating. PDC coating serves as a polymer layer to protect from quick release of drugs from the nanocarriers and increase cellular uptake. The DOX release from Gd@SiO2-DOX/ICG-PDC depends on pH and temperature. The process will be accelerated in the acidic condition than in a neutral pH 7.4. Meanwhile, upon laser irradiation, the photothermal effects promote DOX release and improve the therapeutic efficacy compared to either DOX-loaded Gd@SiO2 or ICG-loaded Gd@SiO2. Moreover, MRI results show that the Gd@SiO2-PDC nanoparticles are safe T1-type MRI contrast agents for imaging. The Gd@SiO2-PDC nanoparticles loaded with DOX and ICG can thus act as a promising theranostic platform for multimodal cancer treatment.

  18. Hollow titania spheres with movable silica spheres inside.

    Science.gov (United States)

    Zhang, Kai; Zhang, Xuehai; Chen, Haitao; Chen, Xin; Zheng, Linli; Zhang, Junhu; Yang, Bai

    2004-12-21

    We demonstrate a flexible method for preparing hollow TiO2 nanospheres with movable silica nanoparticles inside (HTNMSNs). In this method, we used monodisperse silica--polystyrene core--shell nanospheres (SiO2-PS-CSNs) sulfonated as templates and prepared the composite shell consisting of TiO2 and sulfonated polystyrene (SPS) through adsorbing or depositing tetrabutyl titanate gel into the SPS shell. Finally the HTNMSNs were obtained after removal of all polymers in the composite nanospheres by dissolution or calcinations. We investigated the dependence of the morphologies of HTNMSNs on the thickness of PS shells and the size of SiO2 cores and prepared rare earth doped HTNMSNs by a sol-gel process.

  19. Multilayer encapsulated mesoporous silica nanospheres as an oral sustained drug delivery system for the poorly water-soluble drug felodipine.

    Science.gov (United States)

    Hu, Liang; Sun, Hongrui; Zhao, Qinfu; Han, Ning; Bai, Ling; Wang, Ying; Jiang, Tongying; Wang, Siling

    2015-02-01

    We used a combination of mesoporous silica nanospheres (MSN) and layer-by-layer (LBL) self-assembly technology to establish a new oral sustained drug delivery system for the poorly water-soluble drug felodipine. Firstly, the model drug was loaded into MSN, and then the loaded MSN were repeatedly encapsulated by chitosan (CHI) and acacia (ACA) via LBL self-assembly method. The structural features of the samples were studied using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and nitrogen adsorption. The encapsulating process was monitored by zeta-potential and surface tension measurements. The physical state of the drug in the samples was characterized by differential scanning calorimetry (DSC) and X-ray diffractometry (XRD). The influence of the multilayer with different number of layers on the drug release rate was studied using thermal gravimetric analysis (TGA) and surface tension measurement. The swelling effect and the structure changes of the multilayer were investigated to explore the relationship between the drug release behavior and the state of the multilayer under different pH conditions. The stability and mucosa adhesive ability of the prepared nanoparticles were also explored. After multilayer coating, the drug release rate was effectively controlled. The differences in drug release behavior under different pH conditions could be attributed to the different states of the multilayer. And the nanoparticles possessed good stability and strong mucosa adhesive ability. We believe that this combination offers a simple strategy for regulating the release rate of poorly water-soluble drugs and extends the pharmaceutical applications of inorganic materials and polymers.

  20. Fabrication of Silica Nanospheres Coated Membranes: towards the Effective Separation of Oil-in-Water Emulsion in Extremely Acidic and Concentrated Salty Environments.

    Science.gov (United States)

    Chen, Yuning; Liu, Na; Cao, Yingze; Lin, Xin; Xu, Liangxin; Zhang, Weifeng; Wei, Yen; Feng, Lin

    2016-09-06

    A superhydrophilic and underwater superoleophobic surface is fabricated by simply coating silica nanospheres onto a glass fiber membrane through a sol-gel process. Such membrane has a complex framework with micro and nano structures covering and presents a high efficiency (more than 98%) of oil-in-water emulsion separation under harsh environments including strong acidic and concentrated salty conditions. This membrane also possesses outstanding stability since no obvious decline in efficiency is observed after different kinds of oil-in-water emulsions separation, which provides it candidate for comprehensive applicability.

  1. Fabrication of Silica Nanospheres Coated Membranes: towards the Effective Separation of Oil-in-Water Emulsion in Extremely Acidic and Concentrated Salty Environments

    Science.gov (United States)

    Chen, Yuning; Liu, Na; Cao, Yingze; Lin, Xin; Xu, Liangxin; Zhang, Weifeng; Wei, Yen; Feng, Lin

    2016-09-01

    A superhydrophilic and underwater superoleophobic surface is fabricated by simply coating silica nanospheres onto a glass fiber membrane through a sol-gel process. Such membrane has a complex framework with micro and nano structures covering and presents a high efficiency (more than 98%) of oil-in-water emulsion separation under harsh environments including strong acidic and concentrated salty conditions. This membrane also possesses outstanding stability since no obvious decline in efficiency is observed after different kinds of oil-in-water emulsions separation, which provides it candidate for comprehensive applicability.

  2. A NOVEL METHOD TO PREPARE CROSSLINKED POLYETHYLENEIMINE HOLLOW NANOSPHERES

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A novel method to prepare crosslinked polyethyleneimine (CPEI) hollow nanospheres was reported.Uniform silica nanospheres were used as templates,3-aminopropyl trimethoxysilane (APS) was immobilized on the surface of silica nanospheres as couple agent.Aziridine was initiated ring-opening polymerization with the amino groups in APS to form polyethyleneimine (PEI) shell layer.1,4-Butanediol diacrylate was utilized to crosslink PEI polymeric shell.The silica nanospheres in core were etched by hydrofluoric acid to obtain hollow CPEI nanospheres.The hollow nanospheres were characterized by X-ray photoelectron spectroscopy (XPS),transmission electron microscopy (TEM),and thermogravimetric analysis (TGA).

  3. A reduction-sensitive carrier system using mesoporous silica nanospheres with biodegradable polyester as caps.

    Science.gov (United States)

    He, Hongyan; Kuang, Huihui; Yan, Lesan; Meng, Fanbo; Xie, Zhigang; Jing, Xiabin; Huang, Yubin

    2013-09-14

    Mesoporous silica nanoparticles (MSN)-polymer hybrid combined with the aliphatic biodegradable polyester caps on the surface were first developed in order to manipulate the smart intracellular release of anticancer drugs. First, poly(ethylene glycol)-b-poly(ε-caprolactone) (PEG-PCL) was successfully grafted on the surface of MSN via disulfide bonds which could cleave under a reduction environment in tumor cells. The anticancer drug doxorubicin (DOX) was encapsulated into the particle pores. The in vitro drug release profile showed that DOX release was significantly restricted by the polymer caps at pH 7.4, while it was greatly accelerated upon the addition of GSH. Cytotoxicity evaluation showed good biocompatibility with the hybrid particles. Fast endocytosis and intracellular DOX release were observed by confocal laser scanning microscopy (CLSM). The DOX-loaded particles exhibited comparable antitumor activity with free DOX towards HeLa cells and showed in a time-dependent manner. This work developed an extensive method of utilizing aliphatic biodegradable polyesters as polymer caps for MSN to control drug delivery. The paper might offer a potential option for cancer therapy.

  4. A mesoporous silica nanosphere-based drug delivery system using an electrically conducting polymer

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Youngnam; Shi, Riyi; Ben Borgens, Richard [Center for Paralysis Research, School of Veterinary Medicine, Purdue University, West Lafayette, IN 47907 (United States); Ivanisevic, Albena [Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907 (United States)], E-mail: cho22@purdue.edu

    2009-07-08

    In this study, a mesoporous silica nanoparticle (MSN)-based nerve growth factor (NGF) delivery system has been successfully embedded within an electroactive polypyrrol (Ppy). The spherical particles with {approx}100 nm diameter possess a large surface-to-volume ratio for the entrapment of NGF into the pores of MSNs while retaining their bioactivity. Direct incorporation of MSN-NGF within Ppy was achieved during electrochemical polymerization. The loading amount and release profile of NGF from the composite was investigated by sandwich ELISA. The NGF incorporation can be controllable by varying particle concentration or by extending electrodeposition time. The morphology and chemical composition of the Ppy/MSN-NGF composite was evaluated by atomic force microscopy (AFM), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and x-ray photoelectron spectroscopy (XPS). Optical and electron microscopy revealed a characteristic attachment of PC 12 cells and the outgrowth of their neurites when grown on the Ppy/MSN-NGF composite as a result of a sustained and controlled release of NGF. In order to observe the effectiveness of electrical stimulation, neurite extension of cells cultured on unstimulated and stimulated Ppy/MSN-NGF was compared. The NGF release in the presence of electrical stimulation promoted significantly greater neurite extension.

  5. Understanding the role of silica nanospheres with their light scattering and energy barrier properties in enhancing the photovoltaic performance of ZnO based solar cells.

    Science.gov (United States)

    Banik, Avishek; Ansari, Mohammad Shaad; Sahu, Tushar Kanta; Qureshi, Mohammad

    2016-10-12

    The present study discusses the design and development of a dye sensitized solar cell (DSSC) using a hybrid composite of ZnO nanoparticles (ZnO NP) and silica nanospheres (SiO2 NS). A ≈22% enhancement in the overall power conversion efficiency (PCE, η) was observed for the device fabricated with a binary hybrid composite of 1 wt% SiO2 NS and ZnO NP compared to the pristine ZnO NP device. A systematic investigation revealed the dual function of the silica nanospheres in enhancing the device efficacy compared to the bare ZnO NP based device. Sub-micron sized SiO2 NS can boost the light harvesting efficiency of the photoanode by optical confinement, resulting in increased propagation length of the incident light by multiple internal reflections, which was confirmed by UV-Vis diffused reflectance spectroscopy. Electrochemical impedance spectroscopic (EIS) analysis showed a reduced recombination of photo-generated electrons to the I(-)/I3(-) redox shuttle in the case of the composite photoanode. The higher recombination resistance (Rct) in the case of a 1 wt% composite indicates that the SiO2 NS serves as a partial energy barrier layer to retard the interfacial recombination (back transfer) of photo-generated electrons at the working electrode/electrolyte interface, increasing the device efficiency.

  6. 单分散介孔二氧化硅微球的制备%Synthesis of monodisperse mesoporous silica microsphere

    Institute of Scientific and Technical Information of China (English)

    钟立峰; 宁海金; 徐先进; 廖道发

    2012-01-01

    Modified Stober method was used to prepare monodisperse mesoporous silica microsphere by two-step reaction including hydrolysis and condensation of tetraethyl orthosilicate(TEOS)with ammonia as catalyst.Effects of the reaction parameters on the size and mono-disperse of the microsphere were discussed based on many characterization tests.Results showed: the microsphere size increased with the increment of ammonia and TEOS concentrations while decreased at higher temperature due to the evaporation of ammonia;effects of the reaction time on the particle distribution existed mainly in the initial stage,then got smooth gradually.The comparison of small angle X ray analysis suggested that peak intensity of silica microsphere increased and the overlapping peaks drifted rightward after calcination,indicating that the surfactant molecules were removed from the hole and the aperture shrank at the same time.In addition,the texture of the product was affected by reaction conditions to some extent.The mechanism study revealed the formation of silica microsphere was achieved through TEOS hydrolysis and polycondensation two steps successively.This is a simple,effective and repeatable method,which may be used for mass production,for the preparation of mono-dispersed mesoporous silica microspheres.%在Stober方法基础上制备了单分散二氧化硅微球,系统研究了反应条件对成球粒径以及单分散性的影响。通过多种测试手段,发现随着正硅酸乙酯和氨水浓度的提高,成球的粒径逐渐增大;而温度的提高会促使氨水挥发而使得成球的粒径降低;反应时间在反应初期对成球粒径的影响很大,然后逐渐趋于平缓。经对煅烧前后产物的小角X射线衍射对比分析,发现煅烧后产物的峰强度增加,并且重叠峰向右漂移,指示表面活性剂分子从孔中移除并发生了孔径收缩现象,同时发现不同反应条件对产物的织构性质有一定的影响。研究了相关的反应机

  7. Influence of Particle Size on Reaction Selectivity in Cyclohexene Hydrogenation and Dehydrogenation over Silica-Supported Monodisperse Pt Particles

    Energy Technology Data Exchange (ETDEWEB)

    Rioux, R. M.; Hsu, B. B.; Grass, M. E.; Song, H.; Somorjai, Gabor A.

    2008-07-11

    The role of particle size during the hydrogenation/dehydrogenation of cyclohexene (10 Torr C{sub 6}H{sub 10}, 200-600 Torr H{sub 2}, and 273-650 K) was studied over a series of monodisperse Pt/SBA-15 catalysts. The conversion of cyclohexene in the presence of excess H{sub 2} (H{sub 2}:C{sub 6}H{sub 10} ratio = 20-60) is characterized by three regimes: hydrogenation of cyclohexene to cyclohexane at low temperature (< 423 K), an intermediate temperature range in which both hydrogenation and dehydrogenation occur; and a high temperature regime in which the dehydrogenation of cyclohexene dominates (> 573 K). The rate of both reactions demonstrated maxima with temperature, regardless of Pt particle size. For the hydrogenation of cyclohexene, a non-Arrhenius temperature dependence (apparent negative activation energy) was observed. Hydrogenation is structure insensitive at low temperatures, and apparently structure sensitive in the non-Arrhenius regime; the origin of the particle-size dependent reactivity with temperature is attributed to a change in the coverage of reactive hydrogen. Small particles were more active for dehydrogenation and had lower apparent activation energies than large particles. The selectivity can be controlled by changing the particle size, which is attributed to the structure sensitivity of both reactions in the temperature regime where hydrogenation and dehydrogenation are catalyzed simultaneously.

  8. Palladium nanoparticles supported on fibrous-structured silica nanospheres (KCC-1): An efficient and selective catalyst for the transfer hydrogenation of alkenes

    KAUST Repository

    Qureshi, Ziyauddin

    2015-01-09

    An efficient palladium catalyst supported on fibrous silica nanospheres (KCC-1) has been developed for the hydrogenation of alkenes and α,β-unsaturated carbonyl compounds, providing excellent yields of the corresponding products with remarkable chemoselectivity. Comparison (high-resolution TEM, chemisorption) with analogous mesoporous (MCM-41, SBA-15) silica-supported Pd nanocatalysts prepared under identical conditions, demonstrates the advantage of employing the fibrous KCC-1 morphology versus traditional supports because it ensures superior accessibility of the catalytically active cores along with excellent Pd dispersion at high metal loading. This morphology ultimately leads to higher catalytic activity for the KCC-1-supported nanoparticles. The protocol developed for hydrogenation is advantageous and environmentally benign owing to the use of HCOOH as a source of hydrogen, water as a solvent, and because of efficient catalyst recyclability and durability. The recycled catalyst has been analyzed by XPS spectroscopy and TEM showing only minor changes in the oxidation state of Pd and in the morphology after the reaction, thus confirming the robustness of the catalyst.

  9. Sensitivity Improvement of a Humidity Sensor Based on Silica Nanospheres on a Long-Period Fiber Grating

    Science.gov (United States)

    Viegas, Diana; Goicoechea, Javier; Santos, José Luís; Araújo, Francisco Moita; Ferreira, Luís Alberto; Arregui, Francisco J.; Matias, Ignacio R.

    2009-01-01

    This work addresses a new configuration that improves the sensitivity of a humidity sensor based on a long-period fiber grating coated with a SiO2-nanospheres film. An intermediate higher refractive index overlay, deposited through Electrostatic Self-Assembly, is placed between the fiber cladding and the humidity sensitive film in order to increase the total effective refractive index of the coating. With this intermediate design, a three-fold improvement in the sensitivity was obtained. Wavelength shifts up to 15 nm against 5 nm were achieved in a humidity range from 20% to 80%. PMID:22389614

  10. Sensitivity Improvement of a Humidity Sensor Based on Silica Nanospheres on a Long-Period Fiber Grating

    Directory of Open Access Journals (Sweden)

    Javier Goicoechea

    2009-01-01

    Full Text Available This work addresses a new configuration that improves the sensitivity of a humidity sensor based on a long-period fiber grating coated with a SiO2-nanospheres film. An intermediate higher refractive index overlay, deposited through Electrostatic Self-Assembly, is placed between the fiber cladding and the humidity sensitive film in order to increase the total effective refractive index of the coating. With this intermediate design, a three-fold improvement in the sensitivity was obtained. Wavelength shifts up to 15 nm against 5 nm were achieved in a humidity range from 20% to 80%.

  11. Confined crystallization of n-hexadecane located inside microcapsules or outside submicrometer silica nanospheres: a comparison study.

    Science.gov (United States)

    Fu, Dongsheng; Su, Yunlan; Gao, Xia; Liu, Yufeng; Wang, Dujin

    2013-05-23

    Crystallization and phase transition behaviors of n-hexadecane (n-C16H34, abbreviated as C16) confined in microcapsules and n-alkane/SiO2 nanosphere composites have been investigated by the combination of differential scanning calorimetry (DSC) and temperature-dependent X-ray diffraction (XRD). As evident from the DSC measurement, the surface freezing phenomenon of C16 is enhanced in both the microcapsules and SiO2 nanosphere composites because the surface-to-volume ratio is dramatically enlarged in both kinds of confinement. It is revealed from the XRD results that the novel solid-solid phase transition is observed only in the microencapsulated C16, which crystallizes into a stable triclinic phase via a mestastable rotator phase (RI). For the C16/SiO2 composite, however, no novel rotator phase emerges during the cooling process, and C16 crystallizes into a stable triclinic phase directly from the liquid state. Heterogeneous nucleation induced by the surface freezing phase is dominant in the microencapsulated sample and contributes to the emergence of the novel rotator phase, whereas heterogeneous nucleation induced by foreign crystallization nuclei dominates the C16/SiO2 composite, leading to phase transition behaviors similar to those of bulk C16.

  12. Probing hydrodesulfurization over bimetallic phosphides using monodisperse Ni2-xMxP nanoparticles encapsulated in mesoporous silica

    Science.gov (United States)

    Danforth, Samuel J.; Liyanage, D. Ruchira; Hitihami-Mudiyanselage, Asha; Ilic, Boris; Brock, Stephanie L.; Bussell, Mark E.

    2016-06-01

    Metal phosphide nanoparticles encapsulated in mesoporous silica provide a well-defined system for probing the fundamental chemistry of the hydrodesulfurization (HDS) reaction over this new class of hydrotreating catalysts. To investigate composition effects in bimetallic phosphides, the HDS of dibenzothiophene (DBT) was carried out over a series of Ni-rich Ni2-xMxP@mSiO2 (M = Co, Fe) nanocatalysts (x ≤ 0.50). The Ni2-xMxP nanoparticles (average diameters: 11-13 nm) were prepared by solution-phase arrested precipitation and encapsulated in mesoporous silica, characterized by a range of techniques (XRD, TEM, IR spectroscopy, BET surface area, CO chemisorption) and tested for DBT HDS activity and selectivity. The highest activity was observed for a Ni1.92Co0.08P@mSiO2 nanocatalyst, but the overall trend was a decrease in HDS activity with increasing Co or Fe content. In contrast, the highest turnover frequency (TOF) was observed for the most Co- and Fe-rich compositions based on sites titrated by CO chemisorption. IR spectral studies of adsorbed CO on the Ni2-xMxP@mSiO2 catalysts indicate that an increase in electron density occurs on Ni sites as the Co or Fe content is increased, which may be responsible for the increased TOFs of the catalytic sites. The Ni2-xMxP@mSiO2 nanocatalysts exhibit a strong preference for the direct desulfurization pathway (DDS) for DBT HDS that changes only slightly with increasing Co or Fe content.

  13. Synthesis of molecularly imprinted silica nanospheres embedded mercaptosuccinic acid-coated CdTe quantum dots for selective recognition of λ-cyhalothrin

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Xiao [School of Material Science and Engineering, Jiangsu University, Zhenjiang 212013 (China); School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China); Meng, Minjia; Song, Zhilong; Gao, Lin; Li, Hongji [School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China); Dai, Jiangdong; Zhou, Zhiping [School of Material Science and Engineering, Jiangsu University, Zhenjiang 212013 (China); Li, Chunxiang, E-mail: weixiaokeyan@163.com [School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China); Pan, Jianming; Yu, Ping; Yan, Yongsheng [School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China)

    2014-09-15

    In this study, a simple procedure for the determination of λ-cyhalothrin was reported. CdTe quantum dots (QDs) capped by molecularly imprinted polymers (MIPs) were prepared and characterized by spectrofluorometer, Fourier transform infrared spectroscopy (FTIR), transmission electron microscope (TEM) and scanning electron microscope (SEM). Mercaptosuccinic acid (MSA) was chosen as a stabilizer for CdTe QDs synthesis. The MSA stabilizer which comprises both thioglycolic acid (TGA)-like and 3-mercaptopropionic acid (MPA)-like moieties could accelerate the whole growth process of CdTe QDs comparing with TGA-like or MPA-like stabilizer. Meanwhile, the spectrofluorometer was used to evaluate the optical stability, effect of pH, and selective and sensitive determination of λ-cyhalothrin (LC). Moreover, LC could quench the fluorescence of the molecularly imprinted silica nanospheres (CdTe@SiO{sub 2}@MIPs) in a concentration-dependent manner, which was best described by a Stern–Volmer-type equation. - Highlights: • We choose Mercaptosuccinic acid (MSA) as the stabilizer for CdTe QDs synthesis. • The composite materials were prepared by the reverse microemulsion method. • The composite materials can be used for the direct analysis of relevant real samples.

  14. Synthesis of novel core-shell structured dual-mesoporous silica nanospheres and their application for enhancing the dissolution rate of poorly water-soluble drugs

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Chao, E-mail: wuchao27@126.com [Department of Pharmaceutics, Liaoning Medical University, 40 Songpo Road, Linghe District, Jinzhou, Liaoning Province 121001 (China); Sun, Xiaohu [Management Center for Experiments, Bohai University, 19 Keji Road, Songshan District, Jinzhou, Liaoning Province 121000 (China); Zhao, Zongzhe; Zhao, Ying; Hao, Yanna; Liu, Ying [Department of Pharmaceutics, Liaoning Medical University, 40 Songpo Road, Linghe District, Jinzhou, Liaoning Province 121001 (China); Gao, Yu, E-mail: gaoyu_1116@163.com [Department of Medical Oncology, First Affiliated Hospital of Liaoning Medical University, 40 Songpo Road, Linghe District, Jinzhou, Liaoning Province 121001 (China)

    2014-11-01

    Novel core-shell dual-mesoporous silica nanospheres (DMSS) with a tunable pore size were synthesized successfully using a styrene monomer as a channel template for the core and cetyltrimethyl ammonium bromide (CTAB) as a channel template for the shell in order to improve the dissolution rate of poorly water-soluble drugs. Simvastatin was used as a model drug and loaded into DMSS and the mesoporous core without the shell (MSC) by the solvent evaporation method. The drug loading efficiency of DMSS and MSC were determined by thermogravimetric analysis (TGA) and ultraviolet spectroscopy (UV). Characterization, using scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption, powder X-ray diffraction (XRD), differential scanning calorimetry (DSC), and Fourier transform infrared spectroscopy (FTIR) showed that simvastatin adsorbed in DMSS and MSC was in an amorphous state, and in vitro release test results demonstrated that both DMSS and MSC increased the water solubility and dissolution rate of simvastatin. The shell structure of DMSS was able to regulate the release of simvastatin compared with MSC. It is worth noting that DMSS has significant potential as a carrier for improving the dissolution of poorly water-soluble drugs and reducing the rapid release. - Highlights: • A novel core-shell DMSS is prepared for improving the dissolution rate of simvastatin. • The diffusional resistance of the mesoporous shell can delay and regulate drug release. • Simvastatin absorbed in DMSS exists in amorphous form due to spatial confinement.

  15. Soft-to-hard templating to well-dispersed N-doped mesoporous carbon nanospheres via one-pot carbon/silica source copolymerization

    Institute of Scientific and Technical Information of China (English)

    Qinglu Kong; Lingxia Zhang; Min Wang; Mengli Li; Heliang Yao; Jianlin Shi

    2016-01-01

    Here we report a new approach referred as "softto-hard templating" strategy via the copolymerization of carbon source (dopamine) and silica source (tetraethyl orthosilicate) for the synthesis of well dispersed N-doped mesoporous carbon nanospheres (MCNs),which exhibit high performance for electrochemical supercapacitor.This method overcomes the shortcoming of uncontrolled dispersity and complicated procedures of soft-or hard-tem-plating methods,respectively.Moreover,the synthesized MCNs feature enriched heteroatom N-doping and easy functionalization by noble-metal nanoparticles during the one-pot synthesis.All the above characters make the asprepared MCNs a promising platform in a variety of applications.To demonstrate the applicability of the synthesized nitrogen-doped MCNs,this material has been employed as an electrode for high-performance electrochemical supercapacitor,which shows a capacitance of 223 and 140 F/g at current densities of 0.5 and 10 A/g in 1 mol/L KOH electrolyte,respectively.

  16. Synthesis of novel core-shell structured dual-mesoporous silica nanospheres and their application for enhancing the dissolution rate of poorly water-soluble drugs.

    Science.gov (United States)

    Wu, Chao; Sun, Xiaohu; Zhao, Zongzhe; Zhao, Ying; Hao, Yanna; Liu, Ying; Gao, Yu

    2014-11-01

    Novel core-shell dual-mesoporous silica nanospheres (DMSS) with a tunable pore size were synthesized successfully using a styrene monomer as a channel template for the core and cetyltrimethyl ammonium bromide (CTAB) as a channel template for the shell in order to improve the dissolution rate of poorly water-soluble drugs. Simvastatin was used as a model drug and loaded into DMSS and the mesoporous core without the shell (MSC) by the solvent evaporation method. The drug loading efficiency of DMSS and MSC were determined by thermogravimetric analysis (TGA) and ultraviolet spectroscopy (UV). Characterization, using scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption, powder X-ray diffraction (XRD), differential scanning calorimetry (DSC), and Fourier transform infrared spectroscopy (FTIR) showed that simvastatin adsorbed in DMSS and MSC was in an amorphous state, and in vitro release test results demonstrated that both DMSS and MSC increased the water solubility and dissolution rate of simvastatin. The shell structure of DMSS was able to regulate the release of simvastatin compared with MSC. It is worth noting that DMSS has significant potential as a carrier for improving the dissolution of poorly water-soluble drugs and reducing the rapid release.

  17. Multifunctional Mesoporous Silica Nanospheres with Cleavable Gd(III) Chelates as MRI Contrast Agents: Synthesis, Characterization, Target-Specificity, and Renal Clearance

    Science.gov (United States)

    Vivero-Escoto, Juan L.; Taylor-Pashow, Kathryn M. L.; Huxford, Rachel C.; Rocca, Joseph Della; Okoruwa, Christie; An, Hongyu; Lin, Weili

    2013-01-01

    Mesoporous silica nanospheres (MSNs) are a promising material for magnetic resonance imaging (MRI) contrast agents. In this paper multifunctional MSNs with cleavable Gd(III) chelates are synthesized and characterized, and their applicability as MRI contrast agents is demonstrated both in vitro and in vivo. The MSNs contain Gd(III) chelates that are covalently linked via a redox-responsive disulfide moiety. The MSNs are further functionalized with polyethylene glycol (PEG) and an anisamide ligand to improve their biocompatibility and target specificity. The effectiveness of MSNs as an MRI imaging contrast agent and their targeting ability are successfully demonstrated in vitro using human colon adenocarcinoma and pancreatic cancer cells. Finally, the capability of this platform as an in vivo MRI contrast agent is tested using a 3T scanner. The Gd(III) chelate was quickly cleaved by the blood pool thiols and eliminated through the renal excretion pathway. Further tuning of the Gd(III) chelate release kinetics is needed before the MSN system can be used as target-specific MRI contrast agents in vivo. PMID:22069305

  18. Decorating CdTe QD-Embedded Mesoporous Silica Nanospheres with Ag NPs to Prevent Bacteria Invasion for Enhanced Anticounterfeit Applications.

    Science.gov (United States)

    Gao, Yangyang; Dong, Qigeqi; Lan, Shi; Cai, Qian; Simalou, Oudjaniyobi; Zhang, Shiqi; Gao, Ge; Chokto, Harnoode; Dong, Alideertu

    2015-05-13

    Quantum dots (QDs) as potent candidates possess advantageous superiority in fluorescence imaging applications, but they are susceptible to the biological circumstances (e.g., bacterial environment), leading to fluorescence quenching or lose of fluorescent properties. In this work, CdTe QDs were embedded into mesoporous silica nanospheres (m-SiO2 NSs) for preventing QD agglomeration, and then CdTe QD-embedded m-SiO2 NSs (m-SiO2/CdTe NSs) were modified with Ag nanoparticles (Ag NPs) to prevent bacteria invasion for enhanced anticounterfeit applications. The m-SiO2 NSs, which serve as intermediate layers to combine CdTe QDs with Ag NPs, help us establish a highly fluorescent and long-term antibacterial system (i.e., m-SiO2/CdTe/Ag NSs). More importantly, CdTe QD-embedded m-SiO2 NSs showed fluorescence quenching when they encounter bacteria, which was avoided by attaching Ag NPs outside. Ag NPs are superior to CdTe QDs for preventing bacteria invasion because of the structure (well-dispersed Ag NPs), size (small diameter), and surface charge (positive zeta potentials) of Ag NPs. The plausible antibacterial mechanisms of m-SiO2/CdTe/Ag NSs toward both Gram-positive and Gram-negative bacteria were established. As for potential applications, m-SiO2/CdTe/Ag NSs were developed as fluorescent anticounterfeiting ink for enhanced imaging applications.

  19. Synthesis and characterization of radioisotope nanospheres containing two gamma emitters.

    Science.gov (United States)

    Jung, Jin-Hyuck; Jung, Sung-Hee; Kim, Sang-Ho; Choi, Seong-Ho

    2012-12-01

    Silica-coated gold-silver alloy nanospheres prepared by Stöber's method were irradiated in a nuclear reactor to prepare radioisotope nanospheres for use as radiotracers. The radioisotope nanospheres included two gamma nuclides: (i) Au-198, emitting major photons with 0.412 MeV and (ii) Ag-108, emitting photons with 0.434 and 0.633 MeV. The nanospheres shell and core diameters were 100-112 nm and 20-50 nm, respectively, depending on their preparation. The gamma-emitting nanospheres could be used as tracers in high-temperature petrochemical and refinery processes in which conventional organic radioactive labels will decompose.

  20. 二吡啶甲基胺配合物修饰的肿瘤靶向性硅核壳纳米球%Target Cancer Cells through Complexes of Di(picolyl)amine Modified Silica Core-Shell Nanospheres

    Institute of Scientific and Technical Information of China (English)

    陈秋云; 王玲昀; 陈浩; 王娟; 高静

    2010-01-01

    运用油包水微乳液方法制备了二吡啶甲基胺(dpa)及其锰(Ⅱ)和铁(Ⅲ)配合物修饰的Gd-DTPA配合物硅核壳纳米球,其中二吡啶甲基胺锰(Ⅱ)和铁(Ⅲ)配合物修饰的纳米球粒径分别为60和5 nm.体外MRI成像研究表明3种纳米球能显著提高肿瘤细胞的磁共振成像效果,具备良好的肿瘤靶向性.生物活性数据显示三价铁配合物修饰的纳米球具备成像和抑制细胞生长的双重功能,而锰配合物修饰的纳米球不能抑制肿瘤细胞的生长,可作为低毒性的肿瘤成像剂.实验结果显示肿瘤靶向性配合物修饰的纳米球可发展成为新型多功能肿瘤靶向性纳米药物.%Di(picolyl)amine modified silica nanoparticles were prepared by W/O microemulsion method.The coordination of metal ions(Mn(Ⅱ)and Fe(Ⅲ))with di(pycolyl)amine modified nanoparticles produced two different size of nanospheres with the hydrodynamic diameter of approximately 60 nm and 5 nm,respectively.Three grafted silica nanospheres all display a great contrast enhancement in vitro indicating that they could accumulate in cancer cell,selectively.The Fe(Ⅲ)-di(picolyl)amine complex modified nanosphere was a multifunctional nanoparticle to image and inhibit the proliferation of cancer cells,and (Mn(Ⅱ)-di(picolyl)amine codex modified nanosphere could only be used as a low toxic MRI agents.So antitumor complexes modified nanospheres would be new kinds of multifunctional nanoparticles to target the cancer cells actively through complex induced active intracellular accumulating.

  1. Moiré Nanosphere Lithography.

    Science.gov (United States)

    Chen, Kai; Rajeeva, Bharath Bangalore; Wu, Zilong; Rukavina, Michael; Dao, Thang Duy; Ishii, Satoshi; Aono, Masakazu; Nagao, Tadaaki; Zheng, Yuebing

    2015-06-23

    We have developed moiré nanosphere lithography (M-NSL), which incorporates in-plane rotation between neighboring monolayers, to extend the patterning capability of conventional nanosphere lithography (NSL). NSL, which uses self-assembled layers of monodisperse micro/nanospheres as masks, is a low-cost, scalable nanofabrication technique and has been widely employed to fabricate various nanoparticle arrays. Combination with dry etching and/or angled deposition has greatly enriched the family of nanoparticles NSL can yield. In this work, we introduce a variant of this technique, which uses sequential stacking of polystyrene nanosphere monolayers to form a bilayer crystal instead of conventional spontaneous self-assembly. Sequential stacking leads to the formation of moiré patterns other than the usually observed thermodynamically stable configurations. Subsequent O2 plasma etching results in a variety of complex nanostructures. Using the etched moiré patterns as masks, we have fabricated complementary gold nanostructures and studied their optical properties. We believe this facile technique provides a strategy to fabricate complex nanostructures or metasurfaces.

  2. Biodegradable long-circulating polymeric nanospheres.

    Science.gov (United States)

    Gref, R; Minamitake, Y; Peracchia, M T; Trubetskoy, V; Torchilin, V; Langer, R

    1994-03-18

    Injectable nanoparticulate carriers have important potential applications such as site-specific drug delivery or medical imaging. Conventional carriers, however, cannot generally be used because they are eliminated by the reticulo-endothelial system within seconds or minutes after intravenous injection. To address these limitations, monodisperse biodegradable nanospheres were developed from amphiphilic copolymers composed of two biocompatible blocks. The nanospheres exhibited dramatically increased blood circulation times and reduced liver accumulation in mice. Furthermore, they entrapped up to 45 percent by weight of the drug in the dense core in a one-step procedure and could be freeze-dried and easily redispersed without additives in aqueous solutions.

  3. Synthesis of Monodisperse Silica Particles Grafted with Concentrated Ionic Liquid-Type Polymer Brushes by Surface-Initiated Atom Transfer Radical Polymerization for Use as a Solid State Polymer Electrolyte

    Directory of Open Access Journals (Sweden)

    Takashi Morinaga

    2016-04-01

    Full Text Available A polymerizable ionic liquid, N,N-diethyl-N-(2-methacryloylethyl-N-methylammonium bis(trifluoromethylsulfonylimide (DEMM-TFSI, was polymerized via copper-mediated atom transfer radical polymerization (ATRP. The polymerization proceeded in a living manner producing well-defined poly(DEMM-TFSI of target molecular weight up to about 400 K (including a polycation and an counter anion. The accurate molecular weight as determined by a GPC analysis combined with a light scattering measurement, and the molecular weight values obtained exhibited good agreement with the theoretical values calculated from the initial molar ratio of DEMM-TFSI and the monomer conversion. Surface-initiated ATRP on the surface of monodisperse silica particles (SiPs with various diameters was successfully performed, producing SiPs grafted with well-defined poly(DEMM-TFSI with a graft density as high as 0.15 chains/nm2. Since the composite film made from the silica-particle-decorated polymer brush and ionic liquid shows a relatively high ionic conductivity, we have evaluated the relationship between the grafted brush chain length and the ionic conductivity.

  4. Enhanced immunoassay for porcine circovirus type 2 antibody using enzyme-loaded and quantum dots-embedded shell–core silica nanospheres based on enzyme-linked immunosorbent assay

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Long; Li, Xuepu; Shao, Kang; Ye, Shiyi; Liu, Chen; Zhang, Chenjun; Han, Heyou, E-mail: hyhan@mail.hzau.edu.cn

    2015-08-05

    Boosting the detection sensitivity of enzyme-linked immunosorbent assay (ELISA) is significant to the early clinical diagnosis of various diseases. Here, we developed a versatile immunosensor using silica nanospheres as carriers for sensitive detection of porcine circovirus type 2 (PCV2) antibody. With HRP enzyme covalently immobilized on the silica nanospheres and CdSe nanocrystals embedded inside, these signal probes were successfully utilized in the sensitive detection of PCV2 antibody by ELISA, fluorometry and square-wave voltammetry (SWV). To further demonstrate the performance of the immunosensor, Human IgG (HIgG) was used as a model analyte. Since more HRP and CdSe QDs were loaded, 5-, 200- and 400-fold enhancements in amplified ELISA, fluorometry and voltammetry responses for HIgG could be achieved compared to conventional ELISA. The respective detection limits of theses methods for HIgG were 3.9, 0.1 and 0.05 ng mL{sup −1} with a RSD below 5% for amplified ELISA, fluorescence and SWV measurements. Additionally, a 100-fold improvement was obtained in the detection sensitivity for PCV2 antibody immunoassay. The versatile immunosensor exhibits good sensitivity, stability and reproducibility, suggesting its potential applications in clinical diagnostics. - Highlights: • A versatile ELISA-based immunoassay for PCV2 antibody was developed. • Enzyme and CdSe QDs modified SiO{sub 2} particles were used to improve sensitivity. • The simultaneous three ELISA-based techniques enhanced the detection reliability. • The biosensors strategy could provide a new avenue to ELISA-based sensors.

  5. 分子印迹固相萃取检测罐装食品中双酚A%Molecularly imprinted silica nanospheres for solid-phase extraction of bisphenol A in canned food

    Institute of Scientific and Technical Information of China (English)

    史伟; 付绍平; 朱靖博

    2012-01-01

    Molecularly imprinted silica nanospheres with special molecule recognition properties for bisphenol A (BPA ) were prepared with a sol-gel process using bisphenol A as a template molecule, and aminopropyltriethoxysilane(APTES) as a functional monomer. The BPA-imprinted silica nanospheres, as the solid-phase extraction (SPE) sorbents, the SPE conditions were optimized, and dichloromethane was selected as the loading solvent. The selective extraction of BPA from BPA and its three structural analogues BPC, TBBPA and NP showed that the BPA-imprinted silica nanoparticles SPE column had much higher selectivity for BPA with recoveries of 90. 7%. The canned food samples spiked at two concentration levels of 2. 5 and 5 ujnol/L BPA were prepared by SPE column and determined by HPLC with recoverey of 72% - 84% and relative standard deviations( n = 3) of 2. 9% -4.4%.%以双酚A为模板分子,3-氨基丙基乙氧基硅烷为功能单体,通过溶胶-凝胶反应合成双酚A分子印迹纳米硅胶微球.以印迹微球为固相萃取吸附剂,优化固相萃取条件,确定二氯甲烷为上样溶剂.固相萃取选择性实验表明,在双酚A及其结构类似物四溴双酚A、双酚C、壬基酚的混合物溶液中,印迹萃取柱对双酚A具有良好的选择性能,回收率达到90.7%.浓度为2.5和5μmol/L的加标罐装食品样品,经印迹萃取柱预处理,液相色谱检测得到回收率72%~84%,相对标准偏差2.9%~4.4%.

  6. Monodisperse and hollow structured Y{sub 2}O{sub 3}:Ln{sup 3+} (Ln = Eu, Dy, Er, Tm) nanospheres: A facile synthesis and multicolor-tunable luminescence properties

    Energy Technology Data Exchange (ETDEWEB)

    Li, Ruiqing; Zi, Wenwen; Li, Linlin; Liu, Lu; Zhang, Junjun [College of Chemistry, Jilin University, Changchun 130026 (China); Zou, Lianchun, E-mail: zoulianchun@126.com [Teaching Center of Basic Courses, Jilin University, Changchun 130062 (China); Gan, Shucai, E-mail: gansc@jlu.edu.cn [College of Chemistry, Jilin University, Changchun 130026 (China)

    2014-12-25

    Highlights: • We reported a simple route to synthesize the Y{sub 2}O{sub 3} HNSs. • A possible formation mechanism of the Y{sub 2}O{sub 3} HNSs was proposed. • The Ln-doped Y{sub 2}O{sub 3} HNSs exhibit characteristic emission with different colors. • White-light-emitting phosphor Y{sub 2}O{sub 3}:Tm{sup 3+}, Dy{sup 3+} was also successfully synthesized. - Abstract: A novel, fast and simple method was developed to synthesize the undoped and lanthanide-doped yttrium oxide hollow nanospheres (Y{sub 2}O{sub 3}⋅HNSs) with multicolored downconversion emission under mild conditions by employing poly (acrylic acid sodium salt) microspheres (PAAS MSs) as active templates followed by a subsequent calcination process. The structure, morphology, formation process, and fluorescent properties are well investigated using various techniques. The results show that the samples can be well indexed to the pure cubic phase of Y{sub 2}O{sub 3}. The possible formation mechanism of the PAAS MSs, PAA-Y precursor, and Y{sub 2}O{sub 3} HNSs are proposed and discussed in detail. Upon ultraviolet excitation, the obtained Y{sub 2}O{sub 3}:Ln{sup 3+} (Ln = Eu, Dy, Er, Tm) HNSs exhibit strong red, yellow–green, blue, yellow emission, respectively. Moreover, a novel single-phased and near-UV-pumped white-light-emitting phosphor Y{sub 2}O{sub 3}:Tm{sup 3+}, Dy{sup 3+} was also successfully fabricated through optimizing the molar ratio among Tm{sup 3+} and Dy{sup 3+} in the Y{sub 2}O{sub 3} host. This material may find potential applications in field-emission display devices and white ultraviolet light-emitting diodes (UV LEDs). Furthermore, this synthesis route may be of great significance in the preparation of other hollow spherical materials.

  7. Synergistic bactericidal activity of chlorhexidine-loaded, silver-decorated mesoporous silica nanoparticles.

    Science.gov (United States)

    Lu, Meng-Meng; Wang, Qiu-Jing; Chang, Zhi-Min; Wang, Zheng; Zheng, Xiao; Shao, Dan; Dong, Wen-Fei; Zhou, Yan-Min

    2017-01-01

    Combination of chlorhexidine (CHX) and silver ions could engender synergistic bactericidal effect and improve the bactericidal efficacy. It is highly desired to develop an efficient carrier for the antiseptics codelivery targeting infection foci with acidic microenvironment. In this work, monodisperse mesoporous silica nanoparticle (MSN) nanospheres were successfully developed as an ideal carrier for CHX and nanosilver codelivery through a facile and environmentally friendly method. The CHX-loaded, silver-decorated mesoporous silica nanoparticles (Ag-MSNs@CHX) exhibited a pH-responsive release manner of CHX and silver ions simultaneously, leading to synergistically antibacterial effect against both gram-positive Staphylococcus aureus and gram-negative Escherichia coli. Moreover, the effective antibacterial concentration of Ag-MSNs@CHX showed less cytotoxicity on normal cells. Given their synergistically bactericidal ability and good biocompatibility, these nanoantiseptics might have effective and broad clinical applications for bacterial infections.

  8. Estimation of mass thickness response of embedded aggregated silica nanospheres from high angle annular dark-field scanning transmission electron micrographs.

    Science.gov (United States)

    Nordin, M; Abrahamsson, C; Blomqvist, C H; Häbel, H; Röding, M; Olsson, E; Nydén, M; Rudemo, M

    2014-02-01

    In this study, we investigate the functional behaviour of the intensity in high-angle annular dark field scanning transmission electron micrograph images. The model material is a silica particle (20 nm) gel at 5 wt%. By assuming that the intensity response is monotonically increasing with increasing mass thickness of silica, an estimate of the functional form is calculated using a maximum likelihood approach. We conclude that a linear functional form of the intensity provides a fair estimate but that a power function is significantly better for estimating the amount of silica in the z-direction. The work adds to the development of quantifying material properties from electron micrographs, especially in the field of tomography methods and three-dimensional quantitative structural characterization from a scanning transmission electron micrograph. It also provides means for direct three-dimensional quantitative structural characterization from a scanning transmission electron micrograph.

  9. Template synthesis of monodisperse carbon nanodots

    Science.gov (United States)

    Kurdyukov, D. A.; Eurov, D. A.; Stovpiaga, E. Yu.; Kirilenko, D. A.; Konyakhin, S. V.; Shvidchenko, A. V.; Golubev, V. G.

    2016-12-01

    Monodisperse carbon nanodots in pores of mesoporous silica particles are obtained by template synthesis. This method is based on introducing a precursor (organosilane) into pores, its thermal decomposition with formation of carbon nanodots, and the template removal. Structural analysis of the nanomaterial has been performed, which showed that carbon nanodots have an approximately spherical form and a graphite-like structure. According to dynamic light scattering data, the size of carbon nanodots is 3.3 ± 0.9 nm.

  10. PREPARATION OF SINGLE-HOLE HOLLOW POLYMER NANOSPHERES BY RASPBERRY-LIKE TEMPLATE METHOD

    Institute of Scientific and Technical Information of China (English)

    Yong Zhang; Jia-jia Chen; Geng-hui Zhang; Bai-zhu Chen; Hu-sheng Yan

    2013-01-01

    Single-hole hollow polymer nanospheres were fabricated by raspberry-like template method using "graft-from"strategy through atom transfer radical polymerization (ATRP).Nanometer-sized silica spheres were covalently attached onto the surfaces of micrometer-sized silica spheres.Crosslinked polymer shells on the nano-sized spheres outside the attached area were formed by "graft-from" strategy through ATRP.After removal of the silica cores,single-hole hollow crosslinked polymer nanospheres were obtained.In this strategy,most of ATRP monomers may be used and thus many functional groups can be easily incorporated into the single-hole hollow crosslinked polymer nanospheres.

  11. Hypersonic vibrations of Ag@SiO2 (cubic core)-shell nanospheres.

    Science.gov (United States)

    Sun, Jing Ya; Wang, Zhi Kui; Lim, Hock Siah; Ng, Ser Choon; Kuok, Meng Hau; Tran, Toan Trong; Lu, Xianmao

    2010-12-28

    The intriguing optical and catalytic properties of metal-silica core-shell nanoparticles, inherited from their plasmonic metallic cores together with the rich surface chemistry and increased stability offered by their silica shells, have enabled a wide variety of applications. In this work, we investigate the confined vibrational modes of a series of monodisperse Ag@SiO(2) (cubic core)-shell nanospheres synthesized using a modified Stöber sol-gel method. The particle-size dependence of their mode frequencies has been mapped by Brillouin light scattering, a powerful tool for probing hypersonic vibrations. Unlike the larger particles, the observed spheroidal-like mode frequencies of the smaller ones do not scale with inverse diameter. Interestingly, the onset of the deviation from this linearity occurs at a smaller particle size for higher-energy modes than for lower-energy ones. Finite element simulations show that the mode displacement profiles of the Ag@SiO(2) core-shells closely resemble those of a homogeneous SiO(2) sphere. Simulations have also been performed to ascertain the effects that the core shape and the relative hardness of the core and shell materials have on the vibrations of the core-shell as a whole. As the vibrational modes of a particle have a bearing on its thermal and mechanical properties, the findings would be of value in designing core-shell nanostructures with customized thermal and mechanical characteristics.

  12. Utilization of microfluidic V-junction device to prepare surface itraconazole adsorbed nanospheres.

    Science.gov (United States)

    Kucuk, Israfil; Ahmad, Zeeshan; Edirisinghe, Mohan; Orlu-Gul, Mine

    2014-09-10

    Itraconazole is widely used as an anti-fungal drug to treat infections. However, its poor aqueous solubility results in low bioavailability. The aim of the present study was to improve the drug release profile by preparing surface itraconazole adsorbed polymethylsilsesquioxane (PMSQ) nanospheres using a V-junction microfluidic (VJM) device. In order to generate nanospheres with rough surface, the process flow rate of perfluorohexane (PFH) was set between 50 and 300 μl min(-1) while the flow rate of PMSQ and itraconazole solution were constant at 300 μl min(-1). Variations in the PFH flow rate enable the controlled size generation of nanospheres. PMSQ nanospheres adsorbing itraconazole were characterized by SEM, FTIR and Zetasizer. The release of itraconazole from PMSQ nanosphere surface was measured using UV spectroscopy. Nanosphere formulations with a range of sphere size (120, 320 and 800 nm diameter) were generated and drug release was studied. 120 nm itraconazole coated PMSQ nanospheres were found to present highest drug encapsulation efficiency and 13% drug loading in a more reproducible manner compared to 320 nm and 800 nm sized nanosphere formulations. Moreover, 120 nm itraconazole coated PMSQ nanospheres (encapsulation efficiency: 88%) showed higher encapsulation efficiency compared to 320 nm (encapsulation efficiency: 74%) and 800 nm (encapsulation efficiency: 62%) sized nanosphere formulations. The itraconazole coated PMSQ nanospheres were prepared continuously at the rate of 2.6 × 10(6) per minute via VJM device. Overall the VJM device enabled the preparation of monodisperse surface itraconazole adsorbed nanospheres with controlled in vitro drug release profile.

  13. Influence of Template Removal Methods on Mesoporous Silica Nanospheres%模板剂去除方法对介孔氧化硅纳米球的影响

    Institute of Scientific and Technical Information of China (English)

    徐虹; 李延报; 陆春华; 李东旭; 许仲梓

    2011-01-01

    Hexagonal ordered mesoporous silica nanospheres (MSN) with a diameter of 100 nm were obtained by using tetraethoxysilane (TEOS) as silica source and cetyltrimethylammonium bromide (CTAB) as the template under alkaline conditions of 2 M sodium hydroxide. The CTAB templates were removed by calcination at 550℃ and by reflux extraction using HCl/EtOH solution, respectively. Thermogravimetric analysis (TGA), small angle X-ray diffractometry (SAXRD), transmission electron microscopy (TEM) and nitrogen adsorption-desorption techniques were employed to investigate the residue of CTAB and mesoporous structure of MSN. The results indicate that templates can be removed completely by calcination but only about 80% templates can be removed by reflux extraction. The pore size and pore volume of MSN increase with increasing the extraction time and repeated times of extraction. MSN obtained by extraction for 6 h with 4 repeated times to remove templates has the largest surface area (944.31m2 · g-1), pore volume (1.89cm3 · g-1) and pore diameter (2. 56nm).%以十六烷基三甲基溴化铵(CTAB)为模板剂,正硅酸四乙酯(TEOS)为硅源,在碱性条件下反应,分别采用煅烧法和酸化乙醇回流萃取法去除氧化硅中的模板剂,获得了直径为1OOnm分布均匀的六方有序的介孔氧化硅纳米球(MSN).通过热失重分析(TGA)、透射电子显微镜(TEM)、小角度X射线衍射(SAXRD)和氮气吸附-脱附对MSN中CTAB的残余量和介孔结构进行了表征.结果表明:煅烧法能够彻底去除模板剂,萃取法只能去除80%左右的模板剂;随着萃取时间的延长和萃取次数的增加,MSN的孔径和孔容有所增加,其中6h回流萃取4次去除模板剂后得到的MSN的比表面积、孔容、孔径最大,分别为944.31m2·g-1、1.89cm3·g-1和2.56nm.

  14. A general approach for monodisperse colloidal perovskites, Chemistry of Materials

    NARCIS (Netherlands)

    Demirors, A.F.; Imhof, A.

    2009-01-01

    We describe a novel general method for synthesizing monodisperse colloidal perovskite particles at room temperature by postsynthesis addition of metal hydroxides to amorphous titania colloids. In previous work, we used titania particles to synthesize homogenously mixed silica-titania composite parti

  15. Optimization of Broadband Optical Response of Multilayer Nanospheres

    Science.gov (United States)

    2012-07-27

    Lett. 104, 207402 (2010). 2. X. Huang, S. Neretina, and M. A. El-Sayed, “Gold nanorods : From synthesis and properties to biological and biomedical...optimization-based theoretical approach to tailor the optical response of silver /silica multilayer nanospheres over the visible spectrum. We show that the...structure that provides the largest cross-section per volume/mass, averaged over a wide frequency range, is the silver coated silica sphere. We also show

  16. Engineered monodisperse mesoporous materials

    Energy Technology Data Exchange (ETDEWEB)

    Saunders, R.S.; Small, J.H.; Lagasse, R.R.; Schroeder, J.L.; Jamison, G.M.

    1997-08-01

    Porous materials technology has developed products with a wide variety of pore sizes ranging from 1 angstrom to 100`s of microns and beyond. Beyond 15{angstrom} it becomes difficult to obtain well ordered, monodisperse pores. In this report the authors describe efforts in making novel porous material having monodisperse, controllable pore sizes spanning the mesoporous range (20--500 {angstrom}). They set forth to achieve this by using unique properties associated with block copolymers--two linear homopolymers attached at their ends. Block copolymers phase separate into monodisperse mesophases. They desired to selectively remove one of the phases and leave the other behind, giving the uniform monodisperse pores. To try to achieve this the authors used ring-opening metathesis polymerization to make the block copolymers. They synthesized a wide variety of monomers and surveyed their polymers by TGA, with the idea that one phase could be made thermally labile while the other phase would be thermally stable. In the precipitated and sol-gel processed materials, they determined by porosimetry measurements that micropores, mesopores, and macropores were created. In the film processed sample there was not much porosity present. They moved to a new system that required much lower thermal treatments to thermally remove over 90% of the labile phase. Film casting followed by thermal treatment and solvent extraction produced the desired monodisperse materials (based solely on SEM results). Modeling using Density Functional Theory was also incorporated into this project. The modeling was able to predict accurately the domain size and spacing vs. molecular weight for a model system, as well as accurate interfacial thicknesses.

  17. Resorcinol–formaldehyde based carbon nanospheres by electrospraying

    Indian Academy of Sciences (India)

    Chandra S Sharma; Sandip Patil; Suman Saurabh; Ashutosh Sharma; R Venkataraghavan

    2009-06-01

    Carbon nanospheres were synthesized using sol–gel processing of organic and aqueous resorcinol formaldehyde (RF) sols combined with electrospraying technique. RF sol was electrosprayed to form nanodroplets which were collected on a Si wafer. After oven drying at 60°C for 12 h, RF nano-droplets were pyrolyzed at 900°C in an inert atmosphere to yield the carbon nanospheres. This study reports the optimization of various process parameters including needle diameter, applied electric potential and liquid flow rate in order to get spherical, mono-disperse particles. For the organic RF sol, the optimized parameters, needle diameter 0.241 mm, electric potential, 1.5 kV/cm and a flow rate of 0.8 ml/h, enabled the synthesis of nearly monodispersed carbon nano-spheres with diameter of 30.2 ± 7.1 nm. With the same conditions, aqueous RF sol produced irregularly shaped nanoparticles with a smaller mean diameter and much higher variance (17.4 ± 8.0 nm). The surface properties were significantly influenced by the surface morphologies as demonstrated by the water contact angle (WCA) studies. The surface covered with the RF derived carbon nano-spheres was extremely hydrophilic (WCA 10.1°) as compared to a much weaker hydrophilicity of the RF derived carbon films (WCA 83.3°). The hydrophilic carbon nanospheres reported here may have potential applications as adsorbents and in controlled drug delivery, biosensors and carbon-based microelectromechanical systems (C-MEMS) including bio-MEMS.

  18. Formation of isolated carbon nanofibers with hot-wire CVD using nanosphere lithography as catalyst patterning technique

    NARCIS (Netherlands)

    Houweling, Z.S.; Verlaan, V.; ten Grotenhuis, G.T.; Schropp, R.E.I.

    2008-01-01

    Recently the site-density control of carbon nanotubes (CNTs) has attracted much attention as this has become critical for its many applications. To obtain an ordered array of catalyst nanoparticles with good monodispersity nanosphere lithography (NSL) is used. These nanoparticles are tested as catal

  19. Formation of isolated carbon nanofibers with hot-wire CVD using nanosphere lithography as catalyst patterning technique

    NARCIS (Netherlands)

    Houweling, Z.S.; Verlaan, V.; ten Grotenhuis, G.T.; Schropp, R.E.I.

    2008-01-01

    Recently the site-density control of carbon nanotubes (CNTs) has attracted much attention as this has become critical for its many applications. To obtain an ordered array of catalyst nanoparticles with good monodispersity nanosphere lithography (NSL) is used. These nanoparticles are tested as catal

  20. Facile and Scalable Synthesis of Monodispersed Spherical Capsules with a Mesoporous Shell

    KAUST Repository

    Qi, Genggeng

    2010-05-11

    Monodispersed HMSs with tunable particle size and shell thickness were successfully synthesized using relatively concentrated polystyrene latex templates and a silica precursor in a weakly basic ethanol/water mixture. The particle size of the capsules can vary from 100 nm to micrometers. These highly engineered monodispersed capsules synthesized by a facile and scalable process may find applications in drug delivery, catalysis, separationm or as biological and chemical microreactors. © 2010 American Chemical Society.

  1. Synthesis of Water-Based Dispersions of Polymer/TiO2 Hybrid Nanospheres

    Directory of Open Access Journals (Sweden)

    Lu Jin

    2015-08-01

    Full Text Available We develop a strategy for preparing water-based dispersions of polymer/TiO2 nanospheres that can be used to form composite materials applicable in various fields. The formed hybrid nanospheres are monodisperse and possess a hierarchical structure. It starts with the primary TiO2 nanoparticles of about 5 nm, which first assemble to nanoclusters of about 30 nm and then are integrated into monomer droplets. After emulsion polymerization, one obtains the water-based dispersions of polymer/TiO2 nanospheres. To achieve universal size, it is necessary to have treatments with intense turbulent shear generated in a microchannel device at different stages. In addition, a procedure combining synergistic actions of steric and anionic surfactants has been designed to warrant the colloidal stability of the process. Since the formed polymer/TiO2 nanospheres are stable aqueous dispersions, they can be easily mixed with TiO2-free polymeric nanoparticle dispersions to form new dispersions, where TiO2-containing nanospheres are homogeneously distributed in the dispersions at the nanoscale, thus leading to various applications. As an example, the proposed strategy has been applied to generate polystyrene/TiO2 nanospheres of about 100 nm in diameter.

  2. Preparation of large monodisperse vesicles.

    Directory of Open Access Journals (Sweden)

    Ting F Zhu

    Full Text Available Preparation of monodisperse vesicles is important both for research purposes and for practical applications. While the extrusion of vesicles through small pores (approximately 100 nm in diameter results in relatively uniform populations of vesicles, extrusion to larger sizes results in very heterogeneous populations of vesicles. Here we report a simple method for preparing large monodisperse multilamellar vesicles through a combination of extrusion and large-pore dialysis. For example, extrusion of polydisperse vesicles through 5-microm-diameter pores eliminates vesicles larger than 5 microm in diameter. Dialysis of extruded vesicles against 3-microm-pore-size polycarbonate membranes eliminates vesicles smaller than 3 microm in diameter, leaving behind a population of monodisperse vesicles with a mean diameter of approximately 4 microm. The simplicity of this method makes it an effective tool for laboratory vesicle preparation with potential applications in preparing large monodisperse liposomes for drug delivery.

  3. Characterization and in vivo evaluation of novel lipid-chlorambucil nanospheres prepared using a mixture of emulsifiers for parenteral administration.

    Science.gov (United States)

    Song, Honglin; Nie, Shufang; Yang, Xinggang; Li, Ning; Xu, Hongtao; Zheng, Liangyuan; Pan, Weisan

    2010-11-09

    The purpose of the study was to develop and evaluate different lipid-based formulations for parenteral administration, as potential novel carrier systems for lipophilic drugs, and to turn an unstable drug such as chlorambucil into a useful one. A two-stage, high-pressure homogenizer was used to yield a very fine monodispersed lipid nanosphere. The strategy of combining egg yolk phospholipid and nonionic emulsifier (Lutrol F 68 and Tween 80) as an emulsifier mixture was adopted to increase safety and tolerance. The final lipid nanospheres, in a lipophilic mixture consisting of three components, monostearin, medium-chain triglycerides and soya oil, were evaluated for physicochemical properties, such as particle size, surface morphology, drug-entrapment efficiency, drug-loading capacity, lyophilization and in vivo drug-release behavior. A monodispersed lipid nanosphere with a mean particle size ranging from 90 to 150 nm was achieved. The optimized injectable cryoprotectants for lipid nanosphere were sucrose (7.5%) and mannitol (7.5%), which can stabilize the particle size (LD50) at approximately 129 nm after reconstitution. The results show that the formulation can effectively administer anticancer drugs and thus improve patient quality of life. The novel lipid nanosphere complex developed is a useful anticancer drug delivery vehicle for parenteral administration. The formulation strategy has the potential for the development of further methods of drug delivery for a wide variety of anticancer drugs.

  4. Characterization and in vivo evaluation of novel lipid–chlorambucil nanospheres prepared using a mixture of emulsifiers for parenteral administration

    Science.gov (United States)

    Song, Honglin; Nie, Shufang; Yang, Xinggang; Li, Ning; Xu, Hongtao; Zheng, Liangyuan; Pan, Weisan

    2010-01-01

    Purpose The purpose of the study was to develop and evaluate different lipid-based formulations for parenteral administration, as potential novel carrier systems for lipophilic drugs, and to turn an unstable drug such as chlorambucil into a useful one. Methods A two-stage, high-pressure homogenizer was used to yield a very fine monodispersed lipid nanosphere. The strategy of combining egg yolk phospholipid and nonionic emulsifier (Lutrol F 68 and Tween 80) as an emulsifier mixture was adopted to increase safety and tolerance. The final lipid nanospheres, in a lipophilic mixture consisting of three components, monostearin, medium-chain triglycerides and soya oil, were evaluated for physicochemical properties, such as particle size, surface morphology, drug-entrapment efficiency, drug-loading capacity, lyophilization and in vivo drug-release behavior. Results A monodispersed lipid nanosphere with a mean particle size ranging from 90 to 150 nm was achieved. The optimized injectable cryoprotectants for lipid nanosphere were sucrose (7.5%) and mannitol (7.5%), which can stabilize the particle size (LD50) at approximately 129 nm after reconstitution. The results show that the formulation can effectively administer anticancer drugs and thus improve patient quality of life. Conclusions The novel lipid nanosphere complex developed is a useful anticancer drug delivery vehicle for parenteral administration. The formulation strategy has the potential for the development of further methods of drug delivery for a wide variety of anticancer drugs. PMID:21187945

  5. Nanospheric Chemotherapeutic and Chemoprotective Agents

    Science.gov (United States)

    2008-09-01

    targeting the drug-nanosphere complex to diseased cells, thereby minimizing unwanted effects on healthy cells. This report describes the optimization of...military and civilian requirements for effective breast cancer chemotherapy : nontoxic administration, increased bioavailability, prolonged circulation...provide highly effective delivery of hydrophobic paclitaxel to human tumor cells in vitro; (b) tyrosine-derived nanospheres exhibit no toxicity as

  6. Amphiphilic Graft Copolymer Nanospheres: From Colloidal Self-Assembly to CO2 Capture Membranes.

    Science.gov (United States)

    Jeon, Harim; Kim, Dong Jun; Park, Min Su; Ryu, Du Yeol; Kim, Jong Hak

    2016-04-13

    Colloidal nanosphere self-assembly effectively generates ordered nanostructures, prompting tremendous interest in many applications such as photonic crystals and templates for inverse opal fabrication. Here we report the self-assembly of low-cost, graft copolymer nanospheres for CO2 capture membranes. Specifically, poly(dimethylsiloxane)-graft-poly(4-vinylpyridine) (PDMS-g-P4VP) is synthesized via one-pot, free radical dispersion polymerization to give discrete monodisperse nanospheres. These nanospheres comprise a surface-anchored highly permeable PDMS layer and internal CO2-philic P4VP spherical core. Their diameter is controllable below the submicrometer range by varying grafting ratios. The colloidal dispersion forms a long-range, close-packed hexagonal array on a substrate by inclined deposition and convective assembly. The array shows dispersion medium-dependent packing characteristics. A thermodynamic correlation is determined using different solvents to obtain stable PDMS-g-P4VP dispersions and interpreted in terms of Flory-Huggins interaction parameter. As a proof-of-concept, the implementation of these nanospheres into membranes simultaneously enhances the CO2 permeability and CO2/N2 selectivity of PDMS-based transport matrixes. Upon physical aging of the solution, the CO2/N2 selectivity is improved up to 26, one of the highest values for highly permeable PDMS-based polymeric membranes.

  7. 不同粒径单分散SiO2粒子的制备与表面改性%Preparation and Surface Modification of Monodispersed Silica Colloid Particles with Different Dimensions

    Institute of Scientific and Technical Information of China (English)

    刘文军; 罗鲲; 喻亮

    2012-01-01

    TEOS was employed to prepare SiO2 colloid particles in diameters of 290nm, 960nm, 1.3μm and 1.9 μm, respectively,by sol-gel and seed-mediated growth methods. The effect of KH570 treatment on the surface hydro-phobicity of the S1O2 colloid particles was investigated. The SiO2 colloid particles were characterized by particle size analysis, SEM and XRD, which indicate that the products are monodispersed spherical SiO2 particles. Measurements of contact angle, hydroxyl group number and lipophilic degree were also carried out to investigate the modification process, which reveal that the concentration of KH570 and modification time exert a significant effect on the hydro-phobicity of the as^modified S\\Ch colloid particles, where the addition of acetone into the KH570 ethanol solution is more beneficial than water for the surface modification, An ethanol solution containing 1% KH570 with addition of acetone and 6-hour reflux were determined as the optimized condition for the modification of SiO2 particles. The introduction of KH570 into the sol-gel process was able to prepare hydrophobic monodispersed SiO2 particles with a diameter of 1.9μm in one step.%以正硅酸乙酯为原料,采用溶胶-凝胶法及种子生长法制备出不同粒径(290nm、960nm、1.3μm和1.9μm)的SiO2胶体颗粒,并研究了KH570对SiO2胶体颗粒表面疏水性的影响.粒度分析、扫描电镜及X射线衍射分析结果表明,产物均为球形单分散SiO2胶体颗粒;而接触角、表面羟基数和亲油化度等测试结果显示,KH570浓度和改性时间对SiO2胶体表面性质影响显著,且丙酮作为助剂改性效果比水更好,最佳条件是以丙酮为助剂,使用1%KH570回流处理6h.此外,在存在KH570时进行溶胶-凝胶过程可一步制备出直径为1.9μm的单分散SiO2疏水颗粒.

  8. An organosilane-directed growth-induced etching strategy for preparing hollow/yolk–shell mesoporous organosilica nanospheres with perpendicular mesochannels and amphiphilic frameworks

    KAUST Repository

    Zou, Houbing

    2014-06-27

    We have developed an organosilane-directed growth-induced etching strategy to prepare hollow periodic mesoporous organosilica (PMO) nanospheres with perpendicular mesoporous channels and a clear hollow interior as well as an amphiphilic framework. This facile strategy is simple, efficient, and highly controllable. Silica nanospheres were utilized as hard templates to obtain hollow PMO nanospheres through a one-step route, with the structure parameter highly controlled by adjusting the synthesis conditions. Different organosilanes were used to obtain bridged hollow PMO nanospheres of different organic groups and showed different directed capacities. The integrity of the bridged organic group was confirmed by Fourier-transform infrared (FT-IR) spectroscopy and solid-state 13C nuclear magnetic resonance (NMR) spectroscopy. Transmission electron microscopy (TEM) observations showed that the growth of the PMO shell and the dissolution of the silica nanosphere core occurred simultaneously for each nanosphere, while 29Si NMR spectra revealed that the dissolved silica species from the silica nanospheres transformed into PMO shells by co-condensation with hydrolyzed organosilane oligomers. As a result, the obtained hollow nanospheres were amphiphilic, which can even be used as a particle emulsifier for O-W or W-O emulsion in various systems. These materials can also be served as an efficient sorbent for removal of hydrophobic contaminants in water. Using the proposed formation mechanism, this strategy can be extended to transform silica-coated composite materials into yolk-shell structures with a functional interior core and a perpendicular mesoporous amphiphilic shell. As a nanoreactor, the -Ph- bridged amphiphilic shell showed a faster diffusion rate for organic reactants in water than the hydrophilic silica shell, and thus better catalytic activity for reduction of 4-nitrophenol. This journal is © the Partner Organisations 2014.

  9. Preparation of Monodisperse Core-Shell Type Silver-coated Silica Composite-spheres and its Mechanism%单分散核-壳型银包覆二氧化硅微球的制备及复合机理研究

    Institute of Scientific and Technical Information of China (English)

    洪阳; 诸跃进

    2015-01-01

    The synthesis of bare silica is achieved based on Stober method and the synthesis of SiO2@Ag has been obtained by controlled-reduction of silver nitrate and ammonia in ethyl alcohol with PVP as a protective and reducing agent. The particles size, structure and composition analyses reveal that the resultant SiO2@Ag composite-spheres are monodisperse which is well-proportioned and stable with a mean silica core diameter of 255 nm and the silver shell nanoparticles diameter of 8 nm. The synthesis mechanism of the core-shell type composite-spheres is studied in terms of the impact on growth and morphology from these the main factors that are silver source solution, reaction temperature and pH of the reaction solution. The optimal synthesis conditions are finally obtained as follows: the optimum ion concentration is about 2.0 mmol·L-1, the main growth temperature is 40~50℃, and the best core-shell structure appears in pH=12.12.%基于Stober水解法制备得到纯二氧化硅微球,通过以PVP为保护剂和还原剂的可控还原法制备得到银包覆二氧化硅复合微球.该复合微球的单分散性好,且均匀而稳定,其中核的平均粒径在255 nm,壳层银纳米粒子粒径约为8 nm.根据银源溶液的浓度、反应温度以及反应液pH值等3个主要因素对复合微球的生长和形貌的重要影响,研究了该核-壳型复合微球的合成机理,得到最优合成条件:最佳离子浓度为2.0 mmol·L-1,主要生长温度为40~50℃,且最适酸碱度在pH=12.12处.该复合微球在光学和催化等诸多领域都有广泛的潜在应用前景.

  10. Fabrication and Luminescence of Rare Earth Complex/SiO2 Hybrid Nanospheres

    Institute of Scientific and Technical Information of China (English)

    赵丹; 秦伟平; 吴长锋; 张继森; 秦冠仕; 林海燕

    2004-01-01

    The organic rare earth complex was embedded in silica spheres to form inorganic-organic hybrid. Photoactive rare earth complexes with various organic ligands exhibit intense narrow emission band, and the silica is an excellent matrix for inorganic-organic structure. The transmission electron microscope image presents the hybrid nanospheres. The diameter of the hybrid is about 100 nm. The europium complex that incorporated into silica sphere is also proved by the IR spectra, the excitation and emission spectra. The lifetimes of the Eu3+ ions in the hybrid nanospheres and in the pure europium complex were also detected. This hybrid with inhomogeneous compositions exhibits specifically tailored chemical and optical properties, such as perfect thermal and mechanical stability, colorimetric purity and so on. It can be used as luminescent and optical material in EL and PL fields.

  11. Low temperature synthesis and photocatalytic properties of mesoporous TiO{sub 2} nanospheres

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Hua, E-mail: hutang79@yahoo.com.cn [School of Materials Science and Engineering, Jiangsu University, Key Laboratory of High-End Structural Materials of Jiangsu Province, Zhenjiang 212013 (China); Zhang, Du [School of Materials Science and Engineering, Jiangsu University, Key Laboratory of High-End Structural Materials of Jiangsu Province, Zhenjiang 212013 (China); Tang, Guogang [School of Materials Science and Engineering, Jiangsu University, Key Laboratory of High-End Structural Materials of Jiangsu Province, Zhenjiang 212013 (China); Department of Chemical Engineering, Zhenjiang College, Zhenjiang 212003 (China); Ji, Xiaorui [School of Materials Science and Engineering, Jiangsu University, Key Laboratory of High-End Structural Materials of Jiangsu Province, Zhenjiang 212013 (China); Li, Changsheng [School of Materials Science and Engineering, Jiangsu University, Key Laboratory of High-End Structural Materials of Jiangsu Province, Zhenjiang 212013 (China); Department of Chemical Engineering, Zhenjiang College, Zhenjiang 212003 (China); Yan, Xuehua [School of Materials Science and Engineering, Jiangsu University, Key Laboratory of High-End Structural Materials of Jiangsu Province, Zhenjiang 212013 (China); Wu, Qiong, E-mail: wuqiong9918@126.com [Department of Material Science and Engineering, Liaoning University of Technology, Jinzhou 121001 (China)

    2014-04-05

    Highlights: • Uniform mesoporous TiO{sub 2} nanospheres were prepared by a simple method. • The possible formation mechanism of the mesoporous TiO{sub 2} nanospheres was discussed. • The materials exhibit excellent photocatalytic activity. -- Abstract: Facile one-step synthetic method for the fabrication of uniform mesoporous TiO{sub 2} nanospheres was reported on the basis of template-directed deposition and in situ template-sacrificial dissolution, in which SiO{sub 2} nanospheres was employed as the template and (NH{sub 4}){sub 2}TiF{sub 6} was used as the precursor. The deposition of TiO{sub 2} nanoparticles on the surface of template is accompanied with the dissolution of SiO{sub 2} spherical cores by HF generated during the hydrolysis of (NH{sub 4}){sub 2}TiF{sub 6} in the reaction. The obtained products were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), N{sub 2} adsorption–desorption analysis, and UV–visible diffuse reflectance spectroscopy. Furthermore, the photocatalytic activity of samples was evaluated by photocatalytic decolorization of three typical dyes (methyl orange, methylene blue, and rhodamine B) at ambient temperature under UV illumination. The results indicate mesoporous TiO{sub 2} nanospheres exhibited good photocatalytic activity for the degradation of different dyes. These monodisperse mesoporous TiO{sub 2} nanospheres should find various potential applications in photocatalysis, catalysis, solar cell, separation and purification processes.

  12. Sponge-supported synthesis of colloidal selenium nanospheres

    Science.gov (United States)

    Ahmed, Snober; Brockgreitens, John; Xu, Ke; Abbas, Abdennour

    2016-11-01

    With increasing biomedical and engineering applications of selenium nanospheres (SeNS), new efficient methods are needed for the synthesis and long-term preservation of these nanomaterials. Currently, SeNS are mostly produced through the biosynthesis route using microorganisms or by using wet chemical reduction, both of which have several limitations in terms of nanoparticle size, yield, production time and long-term stability of the nanoparticles. Here, we introduce a novel approach for rapid synthesis and long-term preservation of SeNS on a solid microporous support by combining a mild hydrothermal process with chemical reduction. By using a natural sponge as a solid three-dimensional matrix for nanoparticle growth, we have synthesized highly monodisperse spherical nanoparticles with a wide size range (10-1000 nm) and extremely high yield in a relatively short period of time (1 h). Additionally, the synthesized SeNS can be stored and retrieved whenever needed by simply washing the sponge in water. Keeping the nanospheres in the support offers remarkable long-term stability as particles left on the sponge preserve their morphological and colloidal characteristics even after eight months of storage. Furthermore, this work reveals that SeNS can be used for efficient mercury capture from contaminated waters with a record-breaking mercury removal capacity of 1900 mg g-1.

  13. DMSO as a solvent/ligand to monodisperse CdS spherical nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Kaijun [China Pharmaceutical University, Physical Chemistry Lab, School of Science (China); Han, Qiaofeng, E-mail: hanqiaofeng@njust.edu.cn [Nanjing University of Science and Technology, Key Laboratory for Soft Chemistry and Functional Materials, Ministry of Education (China)

    2016-01-15

    Monodisperse CdS nanospheres assembled by small nanoparticles were prepared using dimethyl sulfoxide (DMSO) as a solvent through several routes including thermolysis of xanthate, the reaction of cadmium acetate (Cd(CH{sub 3}CO{sub 2}){sub 2}) with thiourea, and interfacial reaction of CS{sub 2} and Cd(CH{sub 3}CO{sub 2}){sub 2}/DMSO. The corresponding products possessed the particle sizes ranging from around 35 to 45 nm, 63 to 73 nm, and 240 to 280 nm, respectively. These products presented uniform spherical morphology, which provide insights into the effect of DMSO on CdS morphology. DMSO, as an aprotic and polar solvent, possesses unique properties. The oxygen and sulfur atoms in DMSO can coordinate to metal ions on nanoparticles surface, and the high polarity of DMSO is favorable to fast reaction, nucleation, growth, and Ostwald ripening, forming monodisperse nanospheres with narrow size distribution. The influence of CdS size on its photocatalytic activity was evaluated using Rhodamine B (RhB) as a model compound under visible light irradiation.

  14. Water-assisted and surfactant-free synthesis of cobalt ferrite nanospheres via solvothermal method

    Energy Technology Data Exchange (ETDEWEB)

    Bi, Yiqing [CAS Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Beijing 100190 (China); University of the Chinese Academy of Sciences, Beijing 100049 (China); Ren, Yanan [CAS Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Beijing 100190 (China); Bi, Feng [CAS Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Beijing 100190 (China); University of the Chinese Academy of Sciences, Beijing 100049 (China); He, Tao, E-mail: het@nanoctr.cn [CAS Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Beijing 100190 (China)

    2015-10-15

    With ethylene glycol as the solvent, monodispersed cobalt ferrite nanospheres were prepared via a solvothermal method assisted by water. The samples were mainly characterized by X-ray diffraction, scanning electron microscope, and transmission electron microscope. The size of as-prepared products ranges from 10 nm to 200 nm. Size distribution and chemical composition were controlled by the amount of water and pH value in the reaction system. More important, suitable amount of water can avoid the use of surfactant. - Highlights: • Cobalt ferrite nanospheres were synthesized via solvothermal method assisted by water. • An introduction of suitable amount of water can avoid the use of surfactant. • The pH value of the precursor can be used to adjust the product composition.

  15. Wafer Surface Charge Reversal as a Method of Simplifying Nanosphere Lithography for Reactive Ion Etch Texturing of Solar Cells

    Directory of Open Access Journals (Sweden)

    Daniel Inns

    2007-01-01

    Full Text Available A simplified nanosphere lithography process has been developed which allows fast and low-waste maskings of Si surfaces for subsequent reactive ion etching (RIE texturing. Initially, a positive surface charge is applied to a wafer surface by dipping in a solution of aluminum nitrate. Dipping the positive-coated wafer into a solution of negatively charged silica beads (nanospheres results in the spheres becoming electrostatically attracted to the wafer surface. These nanospheres form an etch mask for RIE. After RIE texturing, the reflection of the surface is reduced as effectively as any other nanosphere lithography method, while this batch process used for masking is much faster, making it more industrially relevant.

  16. Aerosol fabrication methods for monodisperse nanoparticles

    Science.gov (United States)

    Jiang, Xingmao; Brinker, C Jeffrey

    2014-10-21

    Exemplary embodiments provide materials and methods for forming monodisperse particles. In one embodiment, the monodisperse particles can be formed by first spraying a nanoparticle-containing dispersion into aerosol droplets and then heating the aerosol droplets in the presence of a shell precursor to form core-shell particles. By removing either the shell layer or the nanoparticle core of the core-shell particles, monodisperse nanoparticles can be formed.

  17. Controlled hydrothermal synthesis of CeO{sub 2} nanospheres and their excellent magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Niu, Xiaofei [Suzhou University, Anhui Key Laboratory of Spintronics and Nanomaterials Research, Suzhou, Anhui (China)

    2017-04-15

    Monodisperse spherical CeO{sub 2} nanostructures with irregular and rough surfaces have successfully been synthesized via a facile hydrothermal technology. XRD, SEM, XPS, Raman scattering, and M-H curves were employed to characterize the samples. The results showed that the spherical CeO{sub 2} nanostructures have a cubic fluorite structure and that there are Ce{sup 3+} ions and oxygen vacancies in the surface of the samples. The M-H curve of CeO{sub 2} nanospheres exhibits excellent room-temperature ferromagnetism (RT-FM), which is likely ascribed to the effects of the Ce{sup 3+} ions and oxygen vacancies. (orig.)

  18. Dispersion behavior of core-shell silica-polymer nanoparticles

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Core-shell silica nanoparticles are superior in modifying surface wetting behavior, enhancing nucleation and growth in crystallization, improving dispersion of naked nanoparticles, and thus upgrading the overall properties of organic polymers. The dispersion behavior and morphology of monodisperse core-shell silica particles in several polymers including polyesters are reviewed and their potential applications are discussed.

  19. Fabrication of Magnetite/Silica/Titania Core-Shell Nanoparticles

    Directory of Open Access Journals (Sweden)

    Suh Cem Pang

    2012-01-01

    Full Text Available Fe3O4/SiO2/TiO2 core-shell nanoparticles were synthesized via a sol-gel method with the aid of sonication. Fe3O4 nanoparticles were being encapsulated within discrete silica nanospheres, and a layer of TiO2 shell was then coated directly onto each silica nanosphere. As-synthesized Fe3O4/SiO2/TiO2 core-shell nanoparticles showed enhanced photocatalytic properties as evidenced by the enhanced photodegradation of methylene blue under UV light irradiation.

  20. Facile One-Step Microwave-Assisted Route towards Ni Nanospheres/Reduced Graphene Oxide Hybrids for Non-Enzymatic Glucose Sensing

    Directory of Open Access Journals (Sweden)

    Mojiao Zhou

    2012-04-01

    Full Text Available In this work, a facile one-step microwave-assisted method for deposition of monodisperse Ni nanospheres on reduced graphene oxide (rGO sheets to form Ni-rGO nanohybrids is discussed. In the presence of hydrazine monohydrate, Ni nanospheres are grown onto rGO sheets using nickel precursor and GO as starting materials in ethylene glycol (EG solution under a low level of microwave irradiation (300 W for 20 min, during which GO is also reduced to rGO. The as-prepared nanohybrids exhibit well-dispersed Ni nanosphere (about 80 nm in diameter loadings and effective reduction of graphene oxide. The resulting Ni-rGO nanohybrids-modified glassy carbon electrode (GCE shows significantly improved electrochemical performance in nonenzymatic amperometric glucose detection. In addition, interference from the oxidation of common interfering species under physiological conditions, such as ascorbic acid (AA and uric acid (UA, is effectively avoided.

  1. Synthesis of 3-D ordered macroporous silicate using the template formed from monodispersed polystyrene latex

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Based on the template formed from monodispersed polystyrene (PS) latex, a modified fast sol-gel process was employed to synthesize a three-dimensional ( 3-D ) ordered macroporous silica material after removing the template by calcination at high temperature. It was indicated that there existed highly ordered packed pores within the whole silica material by SEM morphology observation. It was also found that the pores were interconnected. The pore size could be controlled mainly by varying the particle size of the latex ranging from 101 to 102 nm. The formation process of the ordered pores was also preliminarily discussed.

  2. In-vitro cytotoxicity and cellular uptake studies of luminescent functionalized core-shell nanospheres.

    Science.gov (United States)

    Ansari, Anees A; Hasan, T N; Syed, N A; Labis, J P; Alshatwi, Ali A

    2017-09-01

    Monodispersed luminescent functionalized core-shell nanospheres (LFCSNs) were successfully synthesized and investigated for their cyto-toxic effect on human liver hepatocellular carcinoma cell line (HepG2 cells) by adopting MTT, DNA Ladder, TUNEL assay and qPCR based gene expressions through mRNA quantifications. The TUNEL and DNA ladder assays suggested an insignificant apoptosis in HepG2 cells due to the LFCSNs treatment. Further, the qPCR results also show that the mRNA expressions of cell cycle checkpoint gene p53 and apoptosis related gene (caspase-9) was up-regulated, while the antiapoptotic gene BCl-2 and apoptosis related genes FADD and CAS-3 (apoptosis effecter gene) were down-regulated in the LFCSNs treated cells. The nanospheres that were loaded into the cells confirm their intracellular uptake by light and fluorescent spectro-photometry and microscopy imaging analysis. The loaded nanospheres demonstrate an absolute resistance to photo-bleaching, which were applied for dynamic imaging to real-time tracking in-vitro cell migratory activity for continuous 24 and 48 h durations using a time-lapsed fluorescent microscope. These properties of LFCSNs could therefore promote applications in the area of fluorescent protein biolabeling and drug-delivery.

  3. A Novel Europium Chelate Coated Nanosphere for Time-Resolved Fluorescence Immunoassay.

    Directory of Open Access Journals (Sweden)

    Yifeng Shen

    Full Text Available A novel europium ligand 2,2',2'',2'''-(4,7-diphenyl-1,10-phenanthroline-2,9-diyl bis (methylene bis (azanetriyl tetra acetic acid (BC-EDTA was synthesized and characterized. It shows an emission spectrum peak at 610 nm when it is excited at 360 nm, with a large Stock shift (250 nm. It is covalently coated on the surface of a bare silica nanosphere containi free amino groups, using 1-ethyl-3-(3-dimethylaminopropyl carbodiimide hydrochloride and N-Hydroxysuccinimide. We also observed an interesting phenomenon that when BC-EDTA is labeled with a silica nanosphere, the chelate shows different excitation spectrum peaks of about 295 nm. We speculate that the carboxyl has a significant influence on its excitation spectrum. The BC-EDTA/Eu3+coated nanosphere could be used as a fluorescent probe for time-resolved fluorescence immunoassay. We labeled the antibody with the fluorescent nanosphere to develop a nanosphere based hepatitis B surface antigen as a time-resolved fluorescence immunoassay reagent, which is very easy to operate and eliminates potential contamination of Eu3+ contained in the environment. The analytical and functional sensitivities are 0.0037 μg/L and 0.08 μg/L (S/N≥2.0 respectively. The detection range is 0.08-166.67 μg/L, which is much wider than that of ELISA (0.2-5 μg/L. It is comparable to the commercial dissociation-enhanced lanthanide fluoro-immunoassay system (DELFIA reagents (0.2-145 μg/L. We propose that it can fulfill clinical applications.

  4. Nanospheres of a New Intermetallic FeSn5 Phase: Synthesis, Magnetic Properties and Anode Performance in Li-ion

    Energy Technology Data Exchange (ETDEWEB)

    Wang, X.L.; Feygenson, M.; Chen, H.; Lin, C.-H.; Ku, W.; Bai, J.; Aronson, M.C.; Tyson, T.A.; Han, W.-Q.

    2011-07-27

    We synthesized monodisperse nanospheres of an intermetallic FeSn{sub 5} phase via a nanocrystal-conversion protocol using preformed Sn nanospheres as templates. This tetragonal phase in P4/mcc space group, along with the defect structure Fe{sub 0.74}Sn{sub 5} of our nanospheres, has been resolved by synchrotron X-ray diffraction and Rietveld refinement. Importantly, FeSn{sub 5}, which is not yet established in the Fe-Sn phase diagram, exhibits a quasi-one dimensional crystal structure along the c-axis, thus leading to interesting anisotropic thermal expansion and magnetic properties. Magnetization measurements indicate that nanospheres are superparamagnetic above the blocking temperature T{sub B} = 300 K, which is associated with the higher magnetocrystalline anisotropy constant K = 3.33 kJ m{sup -3}. The combination of the magnetization measurements and first-principles density functional theory calculations reveals the canted antiferromagnetic nature with significant spin fluctuation in lattice a-b plane. The low Fe concentration also leads Fe{sub 0.74}Sn{sub 5} to enhanced capacity as an anode in Li ion batteries.

  5. Room-temperature synthesis of TiO 2 nanospheres and their solar driven photoelectrochemical hydrogen production

    KAUST Repository

    Avasare, Vidya

    2015-08-13

    Highly monodisperse and crystalline anatase phase TiO2 nanospheres have been synthesized at room temperature from organometallic precursor, titanocene dichloride and sodium azide. The photoelectrochemical (PEC) water splitting performance on the TiO2 nanospheres was studied under illumination of AM 1.5G. The optimized photocurrent density and photoconversion efficiency of TiO2 NSPs were observed ~0.95mAcm-2 at 1.23V and 0.69%, respectively. The transient photocurrent response measurements on the TiO2 NSPs during repeated ON/OFF visible light illumination cycles at 1.23V vs RHE show that both samples exhibited fast and reproducible photocurrent responses. The TiO2 NSPs show excellent catalytic stability, and significant dark current was not observed even at high potentials (2.0V vs RHE). © 2015 John Wiley & Sons, Ltd.

  6. Zeptonewton force sensing with nanospheres in an optical lattice

    CERN Document Server

    Ranjit, Gambhir; Casey, Kirsten; Geraci, Andrew A

    2016-01-01

    Optically trapped nanospheres in high-vaccum experience little friction and hence are promising for ultra-sensitive force detection. Here we demonstrate measurement times exceeding $10^5$ seconds and zeptonewton force sensitivity with laser-cooled silica nanospheres trapped in an optical lattice. The sensitivity achieved exceeds that of conventional room-temperature solid-state force sensors, and enables a variety of applications including electric field sensing, inertial sensing, and gravimetry. The optical potential allows the particle to be confined in a number of possible trapping sites, with precise localization at the anti-nodes of the optical standing wave. By studying the motion of a particle which has been moved to an adjacent trapping site, the known spacing of the lattice anti-nodes can be used to calibrate the displacement spectrum of the particle. Finally, we study the dependence of the trap stability and lifetime on the laser intensity and gas pressure, and examine the heating rate of the partic...

  7. Nanoparticle-assisted STED nanoscopy with gold nanospheres

    CERN Document Server

    Urban, Nicolai T; Hell, Stefan W; Sivan, Yonatan

    2016-01-01

    We demonstrate stimulated emission depletion (STED) microscopy with 20 nm gold nanospheres coated by fluorescent silica. Compared with previous demonstrations of STED with a hybrid plasmonic fluorescent label, the current implementation offers a substantially smaller label and a better resolution improvement of up to 2.5-fold beyond the diffraction limit of confocal microscopy. This is achieved at approximately 2 times lower intensity than conventional STED based on dyes alone, and in an aqueous environment, demonstrating the relevance to bio-imaging. Finally, we also show, for the first time in this context, a 3-fold reduction in the rate of photobleaching compared to standard dye-based STED, thus, enabling brighter images.

  8. Enhanced bio-compatibility of ferrofluids of self-assembled superparamagnetic iron oxide-silica core-shell nanoparticles

    Digital Repository Service at National Institute of Oceanography (India)

    Narayanan, T.N.; Mary, A; Swalih, P.K.A; Kumar, D.S.; Makarov, D.; Albrecht, M.; Puthumana, J.; Anas, A; Anantharaman, A

    -interacting, monodispersed and hence the synthesis of such nanostructures has great relevance in the realm of nanoscience. Silica-coated superparamagnetic iron oxide nanoparticles based ferrofluids were prepared using polyethylene glycol as carrier fluid by employing a...

  9. Magnetic polymer nanospheres for anticancer drug targeting

    Energy Technology Data Exchange (ETDEWEB)

    JurIkova, A; Csach, K; Koneracka, M; Zavisova, V; Tomasovicova, N; Lancz, G; Kopcansky, P; Timko, M; Miskuf, J [Institute of Experimental Physics, Slovak Academy of Sciences, 040 01 Kosice (Slovakia); Muckova, M, E-mail: akasard@saske.s [Hameln rds a.s., 900 01 Modra (Slovakia)

    2010-01-01

    Poly(D,L-lactide-co-glycolide) polymer (PLGA) nanospheres loaded with biocom-patible magnetic fluid as a magnetic carrier and anticancer drug Taxol were prepared by the modified nanoprecipitation method with size of 200-250 nm in diameter. The PLGA polymer was utilized as a capsulation material due to its biodegradability and biocompatibility. Taxol as an important anticancer drug was chosen for its significant role against a wide range of tumours. Thermal properties of the drug-polymer system were characterized using thermal analysis methods. It was determined the solubility of Taxol in PLGA nanospheres. Magnetic properties investigated using SQUID magnetometry showed superparamagnetism of the prepared magnetic polymer nanospheres.

  10. Development of monodispersed and functional magnetic polymeric liposomes via simple liposome method

    Energy Technology Data Exchange (ETDEWEB)

    Liang Xiaofei; Wang Hanjie [Tianjin University and Tianjin Key Laboratory of Composites and Functional Materials, Institute of Nanobiotechnology, School of Materials Science and Engineering (China); Jiang Xinguo [Fudan University, School of Pharmacy (China); Chang Jin, E-mail: jinchang@tju.edu.c [Tianjin University and Tianjin Key Laboratory of Composites and Functional Materials, Institute of Nanobiotechnology, School of Materials Science and Engineering (China)

    2010-06-15

    We are reporting a simple and rapid method to prepare superparamagnetic, controlled size, and monodispersed magnetic cationic polymeric liposomes (MCPL) by octadecyl quaternized carboxymethyl chitosan (OQCMC) and cholesterol. The whole process is only about 25 min with simple thin-film dispersion and solvent evaporation method. Hydrophilic magnetic nanoparticles (LM) and hydrophobic magnetic nanoparticles (BM) can be encapsulated into these cationic polymeric liposomes, simultaneously or respectively. A model hydrophobic drug indomethacin can be successfully filled in MCPL with high drug loading capacity 22%. MCPL encapsulating BM also showed strong DNA (pEGFP) binding ability. Drug-loaded MCPL have a long and controlled sustained release profile by changing the number of polymeric lipid layer. These functional MCPL nanospheres can be allowed to serve as ideal candidates for many biomedical applications.Graphical AbstractA simple and rapid liposome method was reported to prepare superparamagnetic, controlled size, and monodispersed magnetic cationic polymeric liposomes (MCPL) by polymeric surfactant, octadecyl quaternized carboxymethyl chitosan (OQCMC), and cholesterol. Hydrophilic Fe{sub 3}O{sub 4} ferrofluid and hydrophobic magnetic nanoparticles can be encapsulated into these cationic polymeric liposomes, simultaneously or respectively. Hydrophobic drug indomethacin can be encapsulated into this MCPL with high encapsulating efficiency and with controlled release profile by changing the number of polymeric lipid layer.

  11. Scanning metallic nanosphere microscopy for vectorial profiling of optical focal spots.

    Science.gov (United States)

    Yi, Hui; Long, Jing; Li, Hongquan; He, Xiaolong; Yang, Tian

    2015-04-06

    Recent years have witnessed fast progress in the development of spatially variant states of polarization under high numerical aperture focusing, and intensive exploration of their applications. We report a vectorial, broadband, high contrast and subwavelength resolution method for focal spot profiling. In this experiment, a 100 nm diameter gold nanosphere on a silica aerogel substrate is raster scanned across the focal spots, and the orthogonal polarization components can be obtained simultaneously by measuring the scattering far field in a confocal manner. The metallic-nanosphere-on-aerogel structure ensures negligible distortion to the focal spots, low crosstalk between orthogonal polarization components (1/39 in experiment), and a low level background noise (1/80 of peak intensity in experiment), while high contrast imaging is not limited by the resonance bandwidth.

  12. Spontaneous Breakup of Extended Monodisperse Polymer Melts

    DEFF Research Database (Denmark)

    Rasmussen, Henrik K.; Yu, Kaijia

    2011-01-01

    We apply continuum mechanical based, numerical modeling to study the dynamics of extended monodisperse polymer melts during the relaxation. The computations are within the ideas of the microstructural ‘‘interchain pressure’’ theory. The computations show a delayed necking resulting in a rupture...

  13. Synthesis and Characterization of Bionanoparticle-Silica Composites and Mesoporous Silica with Large Pores

    Energy Technology Data Exchange (ETDEWEB)

    Niu, Z.; Yang, L.; Kabisatpathy, S.; He, J.; Lee, A.; Ron, J.; Sikha, G.; Popov, B.N.; Emrick, T.; Russell, T. P.; Wang. Q.

    2009-03-24

    A sol-gel process has been developed to incorporate bionanoparticles, such as turnip yellow mosaic virus, cowpea mosaic virus, tobacco mosaic virus, and ferritin into silica, while maintaining the integrity and morphology of the particles. The structures of the resulting materials were characterized by transmission electron microscopy, small angle X-ray scattering, and N{sub 2} adsorption-desorption analysis. The results show that the shape and surface morphology of the bionanoparticles are largely preserved after being embedded into silica. After removal of the bionanoparticles by calcination, mesoporous silica with monodisperse pores, having the shape and surface morphology of the bionanoparticles replicated inside the silica, was produced,. This study is expected to lead to both functional composite materials and mesoporous silica with structurally well-defined large pores.

  14. Synthesis and Characterization of Hollow Magnetic Alloy (GdNi2, Co5Gd Nanospheres Coated with Gd2O3

    Directory of Open Access Journals (Sweden)

    Wang Li

    2014-01-01

    Full Text Available Uniform magnetic hollow nanospheres (GdNi2, Co5Gd coated with Gd2O3 have been successfully prepared on a large scale via a urea-based homogeneous precipitation method using silica (SiO2 spheres as sacrificed templates, followed by subsequent heat treatment. Nitrogen sorption measurements and scanning electron microscope reveal that these hollow-structured magnetic nanospheres have the mesoporous shells that are composed of a large amount of uniform nanoparticles. After reduction treatment, these nanoparticles exhibit superparamagnetism that might have potential applications in medicine. Furthermore, the developed synthesis route may provide an important guidance for the preparation of other multifunctional hollow spherical materials.

  15. Phenylalanine containing hydrophobic nanospheres for antibody purification.

    Science.gov (United States)

    Türkmen, Deniz; Denizli, Adil; Oztürk, Nevra; Akgöl, Sinan; Elkak, Assem

    2008-01-01

    In this study, novel hydrophobic nanospheres with an average size of 158 nm utilizing N-methacryloyl-(L)-phenylalanine methyl ester (MAPA) as a hydrophobic monomer were produced by surfactant free emulsion polymerization of 2-hydroxyethyl methacrylate (HEMA) and MAPA conducted in an aqueous dispersion medium. MAPA was synthesized using methacryloyl chloride and L-phenylalanine methyl ester. Specific surface area of the nonporous nanospheres was found to be 1874 m2/g. Poly(HEMA-MAPA) nanospheres were characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Average particle size, size distribution, and surface charge measurements were also performed. Elemental analysis of MAPA for nitrogen was estimated as 0.42 mmol/g polymer. Then, poly(HEMA-MAPA) nanospheres were used in the adsorption of immunoglobulin G (IgG) in batch system. Higher adsorption values (780 mg/g) were obtained when the poly (HEMA-MAPA) nanospheres were used from both aqueous solutions and human plasma. The adsorption phenomena appeared to follow a typical Langmuir isotherm. It was observed that IgG could be repeatedly adsorbed and desorbed without significant loss in adsorption amount. These findings show considerable promise for this material as a hydrophobic support in industrial processes.

  16. Ultrasmall Carbide Nanospheres - Formation and Electronic Properties

    Science.gov (United States)

    Reinke, Petra; Monazami, Ehsan; McClimon, John

    2015-03-01

    Metallic nanoparticles are highly coveted but are subject to rapid Ostwald ripening even at moderate temperatures limiting study of their properties. Ultrasmall transition metal carbide ``nanospheres'' are synthesized by a solid-state reaction between fullerene as carbon scaffold, and a W surface. This produces nanospheres with a narrow size distribution below 2.5 nm diameter. The nanosphere shape is defined by the scaffold and densely packed arrays can be achieved. The metal-fullerene reaction is temperature driven and progresses through an intermediate semiconducting phase until the fully metallic nanospheres are created at about 350 C. The reaction sequence is observed with STM, and STS maps yield the local density of states. The reaction presumably progresses by stepwise introduction of W-atoms in the carbon scaffold. The results of high resolution STM/STS in combination with DFT calculations are used to unravel the reaction mechanism. We will discuss the transfer of this specific reaction mechanism to other transition metal carbides. The nanospheres are an excellent testbed for the physics and chemistry of highly curved surfaces.

  17. Nanospheres of a New Intermetalic FeSn5 Phase: Synthesis Magnetic Properties and Anode Performance in Li-ion Batteries

    Energy Technology Data Exchange (ETDEWEB)

    X Wang; M Feygenson; H Chen; C Lin; W Ku; J Bai; M Aronson; T Tyson; W Han

    2011-12-31

    We synthesized monodisperse nanospheres of an intermetallic FeSn{sub 5} phase via a nanocrystal-conversion protocol using preformed Sn nanospheres as templates. This tetragonal phase in P4/mcc space group, along with the defect structure Fe{sub 0.74}Sn{sub 5} of our nanospheres, has been resolved by synchrotron X-ray diffraction and Rietveld refinement. Importantly, FeSn{sub 5}, which is not yet established in the Fe-Sn phase diagram, exhibits a quasi-one dimensional crystal structure along the c-axis, thus leading to interesting anisotropic thermal expansion and magnetic properties. Magnetization measurements indicate that nanospheres are superparamagnetic above the blocking temperature T{sub B} = 300 K, which is associated with the higher magnetocrystalline anisotropy constant K = 3.33 kJ m{sup -3}. The combination of the magnetization measurements and first-principles density functional theory calculations reveals the canted antiferromagnetic nature with significant spin fluctuation in lattice a-b plane. The low Fe concentration also leads Fe{sub 0.74}Sn{sub 5} to enhanced capacity as an anode in Li ion batteries.

  18. Nanospheres of a new intermetallic FeSn5 phase: synthesis, magnetic properties and anode performance in Li-ion batteries.

    Science.gov (United States)

    Wang, Xiao-Liang; Feygenson, Mikhail; Chen, Haiyan; Lin, Chia-Hui; Ku, Wei; Bai, Jianming; Aronson, Meigan C; Tyson, Trevor A; Han, Wei-Qiang

    2011-07-27

    We synthesized monodisperse nanospheres of an intermetallic FeSn(5) phase via a nanocrystal-conversion protocol using preformed Sn nanospheres as templates. This tetragonal phase in P4/mcc space group, along with the defect structure Fe(0.74)Sn(5) of our nanospheres, has been resolved by synchrotron X-ray diffraction and Rietveld refinement. Importantly, FeSn(5), which is not yet established in the Fe-Sn phase diagram, exhibits a quasi-one dimensional crystal structure along the c-axis, thus leading to interesting anisotropic thermal expansion and magnetic properties. Magnetization measurements indicate that nanospheres are superparamagnetic above the blocking temperature T(B) = 300 K, which is associated with the higher magnetocrystalline anisotropy constant K = 3.33 kJ m(-3). The combination of the magnetization measurements and first-principles density functional theory calculations reveals the canted antiferromagnetic nature with significant spin fluctuation in lattice a-b plane. The low Fe concentration also leads Fe(0.74)Sn(5) to enhanced capacity as an anode in Li ion batteries.

  19. Ultrasensitive electrochemiluminescence immunoassay for tumor marker based on quantum dots coated carbon nanospheres

    Energy Technology Data Exchange (ETDEWEB)

    Li, Long; Zhang, Yan; Li, Shuai; Wang, Xiu; Li, Chen [Key Laboratory of Chemical Sensing and Analysis in Universities of Shandong, School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022 (China); Ge, Shenguang [Shandong Provincial Key Laboratory of Fluorine Chemistry and Chemical Materials, University of Jinan, Jinan 250022 (China); Yu, Jinghua, E-mail: ujn.yujh@gmail.com [Key Laboratory of Chemical Sensing and Analysis in Universities of Shandong, School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022 (China); Yan, Mei [Key Laboratory of Chemical Sensing and Analysis in Universities of Shandong, School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022 (China); Song, Xianrang [Cancer Research Center, Shandong Tumor Hospital, Jinan 250012 (China)

    2013-12-15

    In this work, a novel electrochemiluminescence (ECL) immunosensor based on CdTe quantum dots (QDs) coated carbon nanosphere (CN/QDs) for the detection of carcinoembryonic antigen (CEA) was developed. The carbon nanospheres (CNs) with good monodispersity and uniform structure were synthetized by a hydrothermal method using glucose as raw material. Then QDs functionized CNs were prepared and employed for signal amplification to improve the sensitivity and the detection limit of immunosensor. For this proposed immunosensor, chitosan was firstly deposited on the pretreated indium tin oxide (ITO) electrode surface, which promoted the electron transfer. Subsequently, gold nanoparticles (AuNPs) were assembled onto chitosan film modified electrode to improve the absorption capacity of antibodies. Then, primary antibodies were immobilized onto the electrode through the reaction between AuNPs and amino. At last bovine serum albumin (BSA) was employed to block the nonspecific binding sites. As a result, a novel ECL immunosensor was obtained on the prepared CN/QDs. The CEA was determined in the range of 0.005–200 ng mL{sup −1}, with a low detection limit of 1.2 pg mL{sup −1} (S/N=3). The proposed ECL immunosensor provides a rapid, simple, and sensitive immunoassay protocol for protein detection, which could be applied in more bioanalytical systems. -- Highlights: • A sandwich-type electrochemluminence immunosensor was fabricated. • CdTe quantum dots coated carbon nanospheres were used to amplify signals. • Au–chitosan biocompatible membrane modified on ITO electrode to capture antibodies.

  20. Monodisperse Platinum and Rhodium Nanoparticles as Model Heterogeneous Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Grass, Michael Edward [Univ. of California, Berkeley, CA (United States)

    2008-09-01

    Model heterogeneous catalysts have been synthesized and studied to better understand how the surface structure of noble metal nanoparticles affects catalytic performance. In this project, monodisperse rhodium and platinum nanoparticles of controlled size and shape have been synthesized by solution phase polyol reduction, stabilized by polyvinylpyrrolidone (PVP). Model catalysts have been developed using these nanoparticles by two methods: synthesis of mesoporous silica (SBA-15) in the presence of nanoparticles (nanoparticle encapsulation, NE) to form a composite of metal nanoparticles supported on SBA-15 and by deposition of the particles onto a silicon wafer using Langmuir-Blodgett (LB) monolayer deposition. The particle shapes were analyzed by transmission electron microscopy (TEM) and high resolution TEM (HRTEM) and the sizes were determined by TEM, X-ray diffraction (XRD), and in the case of NE samples, room temperature H2 and CO adsorption isotherms. Catalytic studies were carried out in homebuilt gas-phase reactors. For the nanoparticles supported on SBA-15, the catalysts are in powder form and were studied using the homebuilt systems as plug-flow reactors. In the case of nanoparticles deposited on silicon wafers, the same systems were operated as batch reactors. This dissertation has focused on the synthesis, characterization, and reaction studies of model noble metal heterogeneous catalysts. Careful control of particle size and shape has been accomplished though solution phase synthesis of Pt and Rh nanoparticles in order to elucidate further structure-reactivity relationships in noble metal catalysis.

  1. Synthesis and Magnetic Properties of Nearly Monodisperse CoFe2O4Nanoparticles Through a Simple Hydrothermal Condition

    Directory of Open Access Journals (Sweden)

    Li Xing-Hua

    2010-01-01

    Full Text Available Abstract Nearly monodisperse cobalt ferrite (CoFe2O4 nanoparticles without any size-selection process have been prepared through an alluring method in an oleylamine/ethanol/water system. Well-defined nanospheres with an average size of 5.5 nm have been synthesized using metal chloride as the law materials and oleic amine as the capping agent, through a general liquid–solid-solution (LSS process. Magnetic measurement indicates that the particles exhibit a very high coercivity at 10 K and perform superparamagnetism at room temperature which is further illuminated by ZFC/FC curves. These superparamagnetic cobalt ferrite nanomaterials are considered to have potential application in the fields of biomedicine. The synthesis method is possible to be a general approach for the preparation of other pure binary and ternary compounds.

  2. Gemcitabine-loaded magnetic albumin nanospheres for cancer chemohyperthermia

    Science.gov (United States)

    Li, Hongbo; Ke, Fei; An, Yanli; Hou, Xinxin; Zhang, Hao; Lin, Mei; Zhang, Dongsheng

    2013-03-01

    Eliminating cancer without harming normal body tissue remains a longstanding challenge in medicine. Toward this goal, we prepared nanosized magnetic albumin nanospheres encapsulating magnetic nanoparticles (Fe3O4) and antitumor drugs (Gemcitabine, GEM). Magnetic albumin nanospheres (average size ≈ 224 nm) had good magnetic responsiveness upon exposure to an alternating magnetic field even though Fe3O4 was encased in nanospheres. Thermodynamic test showed that Fe3O4 could serve as a heating source under AMF and lead the nanospheres to reach their steady temperature (45 °C). The release results in vitro indicated that nanospheres had an obvious effect of sustained release of GEM. The result of cytotoxicity assay showed that the toxicity of this material was classified as grade 1, which belongs to no cytotoxicity. The antitumor efficacy of the GEM/Fe3O4 albumin nanospheres combined with magnetic fluid hyperthermia on non-small lung cancer cell line GlC-82 was examined by MTT assay and flow cytometry assay. Compared with nanospheres entrapping GEM group, nanospheres entrapping Fe3O4 combined with MFH group, and GEM/Fe3O4 albumin nanospheres without MFH group, the GEM/Fe3O4 albumin nanospheres exhibited enhanced antitumor efficacy. Thus, the GEM/Fe3O4 albumin nanospheres have promising applications in cancer treatment.

  3. Synthesis and characterization of gold-deposited red, green and blue fluorescent silica nanoparticles for biosensor application.

    Science.gov (United States)

    Lee, Kyoung G; Wi, Rinbok; Park, Tae Jung; Yoon, Sun Hong; Lee, Jaebeom; Lee, Seok Jae; Kim, Do Hyun

    2010-09-14

    Fluorescent silica nanoparticles deposited with highly monodisperse gold nanoparticles (1-2 nm) were synthesized via the W/O method and intensive ultrasound irradiation. A large surface area of gold-doped fluorescent silica nanoparticle serves as a platform to immobilize a specific binding protein for biomolecules interaction in bioimaging applications.

  4. Poly(ionic liquids) hollow nanospheres with PDMAEMA as joint support of highly dispersed gold nanoparticles for thermally adjustable catalysis

    Energy Technology Data Exchange (ETDEWEB)

    He, Xiaoyan, E-mail: hexy09@163.com; Liu, Zhirong; Fan, Fuhong; Qiang, Shenglu; Cheng, Li; Yang, Wu, E-mail: yangw@nwnu.edu.cn [Northwest Normal University, Key Lab of Bioelectrochemistry and Environmental Analysis of Gansu Province, College of Chemistry and Chemical Engineering (China)

    2015-02-15

    A smart hollow hybrid system was prepared by introducing poly(2-(1-methylimidazolium 3-yl)-ethyl methacrylate chloride) (PMIMC) network, the temperature-responsive PDMAEMA brushes, and Au nanoparticles into silica nanoparticles through two-step surface-initiated atom transfer radical polymerization. TEM, FTIR, EDX, XRD, XPS, and TGA were used to characterize the morphology and structure of air@PMIMC–PDMAEMA–Au hairy hollow nanospheres. The result showed that Au nanoparticles with an average diameter of 1.5 ± 0.2 nm were homogeneously embedded inside the PMIMC–PDMAEMA shell. Catalytic activity of the as-synthesized air@PMIMC–PDMAEMA–Au hairy hollow nanospheres were investigated using the reduction of 4-nitrophenol with NaBH{sub 4} as a model reaction. It was found that the joint structures of PMIMC hollow nanospheres and PDMAEMA brushes lead to production of the highly active and stable catalyst for reduction of 4-nitrophenol. Furthermore, the obtained air@PMIMC–PDMAEMA–Au hairy hollow nanospheres were found to have a thermally adjustable catalytic activity for the reduction of 4-nitrophenol.

  5. Mesoporous silica nanoparticles for active corrosion protection.

    Science.gov (United States)

    Borisova, Dimitriya; Möhwald, Helmuth; Shchukin, Dmitry G

    2011-03-22

    This work presents the synthesis of monodisperse, mesoporous silica nanoparticles and their application as nanocontainers loaded with corrosion inhibitor (1H-benzotriazole (BTA)) and embedded in hybrid SiOx/ZrOx sol-gel coating for the corrosion protection of aluminum alloy. The developed porous system of mechanically stable silica nanoparticles exhibits high surface area (∼1000 m2·g(-1)), narrow pore size distribution (d∼3 nm), and large pore volume (∼1 mL·g(-1)). As a result, a sufficiently high uptake and storage of the corrosion inhibitor in the mesoporous nanocontainers was achieved. The successful embedding and homogeneous distribution of the BTA-loaded monodisperse silica nanocontainers in the passive anticorrosive SiOx/ZrOx film improve the wet corrosion resistance of the aluminum alloy AA2024 in 0.1 M sodium chloride solution. The enhanced corrosion protection of this newly developed active system in comparison to the passive sol-gel coating was observed during a simulated corrosion process by the scanning vibrating electrode technique (SVET). These results, as well as the controlled pH-dependent release of BTA from the mesoporous silica nanocontainers without additional polyelectrolyte shell, suggest an inhibitor release triggered by the corrosion process leading to a self-healing effect.

  6. One-pot synthesis of core-shell Cu@SiO2 nanospheres and their catalysis for hydrolytic dehydrogenation of ammonia borane and hydrazine borane

    Science.gov (United States)

    Yao, Qilu; Lu, Zhang-Hui; Zhang, Zhujun; Chen, Xiangshu; Lan, Yaqian

    2014-12-01

    Ultrafine copper nanoparticles (Cu NPs) within porous silica nanospheres (Cu@SiO2) were prepared via a simple one-pot synthetic route in a reverse micelle system and characterized by SEM, TEM, EDX, XRD, N2 adsorption-desorption, CO-TPD, XPS, and ICP methods. The characterized results show that ultrafine Cu NPs with diameter of around 2 nm are effectively embedded in the center of well-proportioned spherical SiO2 NPs of about 25 nm in diameter. Compared to commercial SiO2 supported Cu NPs, SiO2 nanospheres supported Cu NPs, and free Cu NPs, the synthesized core-shell nanospheres Cu@SiO2 exhibit a superior catalytic activity for the hydrolytic dehydrogenation of ammonia borane (AB, NH3BH3) and hydrazine borane (HB, N2H4BH3) under ambient atmosphere at room temperature. The turnover frequencies (TOF) for the hydrolysis of AB and HB in the presence of Cu@SiO2 nanospheres were measured to be 3.24 and 7.58 mol H2 (mol Cu min)-1, respectively, relatively high values for Cu nanocatalysts in the same reaction. In addition, the recycle tests show that the Cu@SiO2 nanospheres are still highly active in the hydrolysis of AB and HB, preserving 90 and 85% of their initial catalytic activity even after ten recycles, respectively.

  7. Integrating nanosphere lithography in device fabrication

    Science.gov (United States)

    Laurvick, Tod V.; Coutu, Ronald A.; Lake, Robert A.

    2016-03-01

    This paper discusses the integration of nanosphere lithography (NSL) with other fabrication techniques, allowing for nano-scaled features to be realized within larger microelectromechanical system (MEMS) based devices. Nanosphere self-patterning methods have been researched for over three decades, but typically not for use as a lithography process. Only recently has progress been made towards integrating many of the best practices from these publications and determining a process that yields large areas of coverage, with repeatability and enabled a process for precise placement of nanospheres relative to other features. Discussed are two of the more common self-patterning methods used in NSL (i.e. spin-coating and dip coating) as well as a more recently conceived variation of dip coating. Recent work has suggested the repeatability of any method depends on a number of variables, so to better understand how these variables affect the process a series of test vessels were developed and fabricated. Commercially available 3-D printing technology was used to incrementally alter the test vessels allowing for each variable to be investigated individually. With these deposition vessels, NSL can now be used in conjunction with other fabrication steps to integrate features otherwise unattainable through current methods, within the overall fabrication process of larger MEMS devices. Patterned regions in 1800 series photoresist with a thickness of ~700nm are used to capture regions of self-assembled nanospheres. These regions are roughly 2-5 microns in width, and are able to control the placement of 500nm polystyrene spheres by controlling where monolayer self-assembly occurs. The resulting combination of photoresist and nanospheres can then be used with traditional deposition or etch methods to utilize these fine scale features in the overall design.

  8. Synthesis of uniform and size-controllable carbon nanospheres by a simple hydrothermal method and fabrication of carbon nanosphere super-hydrophobic surface

    Energy Technology Data Exchange (ETDEWEB)

    Joula, Mohsen Heidari; Farbod, Mansoor, E-mail: farbod_m@scu.ac.ir

    2015-08-30

    Highlights: • A simple hydrothermal method was used to produce carbon nanospheres (CNSs). • The size of CNSs was controlled by the concentration of initial sucrose solution. • The size of CNSs was reduced to 100 nm by post-annealing of the CNSs. • A glass substrate was coated with CNSs thick film using spin coating method. • Contact angle of a water droplet was 153° indicating the film is super-hydrophobic. - Abstract: A simple hydrothermal method was used to produce high yield, monodisperse and tightly controllable size of carbon nanospheres (CNSs) by adjusting the concentration of initial sucrose solution in a sealed autoclave at 170 °C for 8 h. By changing the solution concentration from 0.5 to 0.1 mol l{sup −1}, the sizes of carbon spheres (CS) were reduced from about 2500 to about 300 nm. Also by increasing the solution volume to the vessel volume ratio (V{sub s}/V{sub v}) from 5/6 to 11/13, the yield of CS was increased from 25% up to about 55% of initial raw materials. It was found that by post-annealing of the 300 nm CNSs at 435 °C for 30 min, their diameters were reduced to 100 nm. Moreover, annealing in air atmosphere had a noticeable influence on the surface functional groups and bonds of CNSs. In addition, CNSs were used to fabricate hydrophobic surfaces by coating their ethanolic colloidal solution on glass substrates. The measured contact angle (CA) of a water droplet was about 153°, indicating that the CNSs thick layers were super-hydrophobic. The size dependence of CNSs on the different parameters has been discussed.

  9. Converting ceria polyhedral nanoparticles into single-crystal nanospheres.

    Science.gov (United States)

    Feng, Xiangdong; Sayle, Dean C; Wang, Zhong Lin; Paras, M Sharon; Santora, Brian; Sutorik, Anthony C; Sayle, Thi X T; Yang, Yi; Ding, Yong; Wang, Xudong; Her, Yie-Shein

    2006-06-09

    Ceria nanoparticles are one of the key abrasive materials for chemical-mechanical planarization of advanced integrated circuits. However, ceria nanoparticles synthesized by existing techniques are irregularly faceted, and they scratch the silicon wafers and increase defect concentrations. We developed an approach for large-scale synthesis of single-crystal ceria nanospheres that can reduce the polishing defects by 80% and increase the silica removal rate by 50%, facilitating precise and reliable mass-manufacturing of chips for nanoelectronics. We doped the ceria system with titanium, using flame temperatures that facilitate crystallization of the ceria yet retain the titania in a molten state. In conjunction with molecular dynamics simulation, we show that under these conditions, the inner ceria core evolves in a single-crystal spherical shape without faceting, because throughout the crystallization it is completely encapsulated by a molten 1- to 2-nanometer shell of titania that, in liquid state, minimizes the surface energy. The principle demonstrated here could be applied to other oxide systems.

  10. Microfluidic Production of Monodisperse Perfluorocarbon Microdroplets

    Science.gov (United States)

    Li, David; Schalte, Kevin; Fowlkes, J. Brian; Bull, Joseph

    2010-11-01

    Acoustic droplet vaporization (ADV) is process in which liquid perfluorocarbon (PFC) microdroplets are vaporized using focused ultrasound to form gas bubbles that are approximately 125 times larger in volume. Gas embolotherapy is a novel cancer treatment that uses ADV in vivo to strategically form gas emoboli, which can lodge in the microcirculation and starve tumors. Current methods to produce PFC microdroplets, such has high speed shaking or sonication, result in polydisperse droplet distributions where a fraction of droplets fall within the 2-10 microns range. In the clinical application with such a droplet distribution, large droplets are filtered by the lungs and small droplets result in bubbles that are too small to lodge in the tumor vasculature. Consequently, there is a need for a monodisperse droplet distribution. A microfluidic based device has been developed in order to produce such monodisperse PFC microdroplets. The device used hydrodynamic flow focusing to create droplets with a mean diameter less than 10 microns in diameter. This work is supported by NIH grant R01EB006476.

  11. Biofunctionalized magnetic hydrogel nanospheres of magnetite and {kappa}-carrageenan

    Energy Technology Data Exchange (ETDEWEB)

    Daniel-da-Silva, Ana L; Fateixa, Sara; Trindade, Tito; Goodfellow, Brian J; Gil, Ana M [Department of Chemistry, CICECO, University of Aveiro, 3810-193 Aveiro (Portugal); Guiomar, Antonio J [Department of Biochemistry and CNC, University of Coimbra, 3001-401 Coimbra (Portugal); Costa, Benilde F O [CEMDRX, Department of Physics, University of Coimbra, 3004-516 Coimbra (Portugal); Silva, Nuno J O, E-mail: ana.luisa@ua.p [Instituto de Ciencias de Materiales de Aragon, Departamento de Fisica de la Materia Condensada, Facultad de Ciencias, CSIC-Universidad de Zaragoza, 50009 Zaragoza (Spain)

    2009-09-02

    Magnetic hydrogel {kappa}-carrageenan nanospheres were successfully prepared via water-in-oil (w/o) microemulsions combined with thermally induced gelation of the polysaccharide. The size of the nanospheres (an average diameter () of about 50 and 75 nm) was modulated by varying the concentration of surfactant. The nanospheres contained superparamagnetic magnetite nanoparticles (8 nm), previously prepared by co-precipitation within the biopolymer. Carboxyl groups, at a concentration of about 4 mmol g{sup -1}, were successfully grafted at the surface of these magnetic nanospheres via carboxymethylation of the {kappa}-carrageenan. The carboxylated nanospheres were shown to be thermo-sensitive in the 37-45 {sup 0}C temperature range, indicating their potential as thermally controlled delivery systems for drugs and/or magnetic particles at physiological temperatures. Finally, preliminary results have been obtained for IgG antibody conjugation of the carboxylated nanospheres and the potential of these systems for bio-applications is discussed.

  12. Preparation and antibacterial activities of hollow silica-Ag spheres.

    Science.gov (United States)

    Lin, Lin; Zhang, Haifang; Cui, Haiying; Xu, Mingqiang; Cao, Shunsheng; Zheng, Guanghong; Dong, Mingdong

    2013-01-01

    Hollow silica spheres with round mesoporous shells were synthesized by core-shell template method, using monodispersed cationic polystyrene particles as core, and TEOS (tetraethoxysilane) as the silica source to form shell. After calcination at 550°C, uniform spheres with a thin shell of silica and hollow interior structures. Transmission electron microscopy results showed that the size of the spheres is about 700 nm in diameter with narrow distribution. In addition, the spheres have a high surface area of 183 m(2)/g. The spheres were subsequently used as silver-loading substrates and the silver loaded spheres were tested in antimicrobial study against gram negative bacteria Eschrichia coli in vitro. The hollow silica-Ag spheres proved significantly higher antibacterial efficacy against E. coli as compared to that of the common silica-Ag particles.

  13. Synthesis of 3D ordered porous polystyrene using silica template

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A rigid colloidal silica template was formed by self-assembly ofthe monodispersed silica spheres prepared according to St-ber method. The silica template is highly ordered, which was verified by bright color effect due to Bragg diffraction and the results of SEM. The free radical polymerization of styrene was allowed within the interstices of the rigid template to result in the formation of the three- dimensional periodic silica/polystyrene nano-composites. The titled porous polystyrene was prepared by chemical decom- position of the template with concentrated aqueous hydro- fluoric acid. Scanning electron microscopy characterization showed that the macroporous polystyrene has ordered arrays of the uniform pores replicated from the template. Moreover, it was found that the morphology of the as-synthesized macroporous polystyrene was greatly affected by the connectivity of the silica spheres treated under different conditions.

  14. Elongational viscosity of monodisperse and bidisperse polystyrene melts

    DEFF Research Database (Denmark)

    Nielsen, Jens Kromann; Rasmussen, Henrik K.; Hassager, Ole

    2006-01-01

    The start-up and steady uniaxial elongational viscosity have been measured for two monodisperse polystyrene melts with molecular weights of 52 and 103 kg/mole, and for three bidisperse polystyrene melts. The monodisperse melts show a maximum in the steady elongational viscosity vs. the elongation...

  15. Monodisperse porous silicon spheres as anode materials for lithium ion batteries.

    Science.gov (United States)

    Wang, Wei; Favors, Zachary; Ionescu, Robert; Ye, Rachel; Bay, Hamed Hosseini; Ozkan, Mihrimah; Ozkan, Cengiz S

    2015-03-05

    Highly monodisperse porous silicon nanospheres (MPSSs) are synthesized via a simple and scalable hydrolysis process with subsequent surface-protected magnesiothermic reduction. The spherical nature of the MPSSs allows for a homogenous stress-strain distribution within the structure during lithiation and delithiation, which dramatically improves the electrochemical stability. To fully extract the real performance of the MPSSs, carbon nanotubes (CNTs) were added to enhance the electronic conductivity within the composite electrode structure, which has been verified to be an effective way to improve the rate and cycling performance of anodes based on nano-Si. The Li-ion battery (LIB) anodes based on MPSSs demonstrate a high reversible capacity of 3105 mAh g(-1). In particular, reversible Li storage capacities above 1500 mAh g(-1) were maintained after 500 cycles at a high rate of C/2. We believe this innovative approach for synthesizing porous Si-based LIB anode materials by using surface-protected magnesiothermic reduction can be readily applied to other types of SiOx nano/microstructures.

  16. Silica Nephropathy

    Directory of Open Access Journals (Sweden)

    N Ghahramani

    2010-06-01

    Full Text Available Occupational exposure to heavy metals, organic solvents and silica is associated with a variety of renal manifestations. Improved understanding of occupational renal disease provides insight into environmental renal disease, improving knowledge of disease pathogenesis. Silica (SiO2 is an abundant mineral found in sand, rock, and soil. Workers exposed to silica include sandblasters, miners, quarry workers, masons, ceramic workers and glass manufacturers. New cases of silicosis per year have been estimated in the US to be 3600–7300. Exposure to silica has been associated with tubulointerstitial disease, immune-mediated multisystem disease, chronic kidney disease and end-stage renal disease. A rare syndrome of painful, nodular skin lesions has been described in dialysis patients with excessive levels of silicon. Balkan endemic nephropathy is postulated to be due to chronic intoxication with drinking water polluted by silicates released during soil erosion. The mechanism of silica nephrotoxicity is thought to be through direct nephrotoxicity, as well as silica-induced autoimmune diseases such as scleroderma and systemic lupus erythematosus. The renal histopathology varies from focal to crescentic and necrotizing glomerulonephritis with aneurysm formation suggestive of polyarteritis nodosa. The treatment for silica nephrotoxicity is non-specific and depends on the mechanism and stage of the disease. It is quite clear that further research is needed, particularly to elucidate the pathogenesis of silica nephropathy. Considering the importance of diagnosing exposure-related renal disease at early stages, it is imperative to obtain a thorough occupational history in all patients with renal disease, with particular emphasis on exposure to silica, heavy metals, and solvents.

  17. Construction of tubular polypyrrole-wrapped biomass-derived carbon nanospheres as cathode materials for lithium-sulfur batteries

    Science.gov (United States)

    Yu, Qiuhong; Lu, Yang; Peng, Tao; Hou, Xiaoyi; Luo, Rongjie; Wang, Yange; Yan, Hailong; Liu, Xianming; Kim, Jang-Kyo; Luo, Yongsong

    2017-03-01

    A promising hybrid material composed of tubular polypyrrole (T-PPy)-wrapped monodisperse biomass-derived carbon nanospheres (BCSs) was first synthesized successfully via a simple hydrothermal approach by using watermelon juice as the carbon source, and further used as an anchoring object for sulfur (S) of lithium-sulfur (Li-S) batteries. The use of BCSs with hydrophilic nature as a framework could provide large interface areas between the active materials and electrolyte, and improve the dispersion of T-PPy, which could help in the active material utilization. As a result, BCS@T-PPy/S as a cathode material exhibited a high capacity of 1143.6 mA h g-1 and delivered a stable capacity up to 685.8 mA h g-1 after 500 cycles at 0.5 C, demonstrating its promising application for rechargeable Li-S batteries.

  18. Sympathetic cooling of nanospheres with cold atoms

    Science.gov (United States)

    Montoya, Cris; Witherspoon, Apryl; Ranjit, Gambhir; Casey, Kirsten; Kitching, John; Geraci, Andrew

    2016-05-01

    Ground state cooling of mesoscopic mechanical structures could enable new hybrid quantum systems where mechanical oscillators act as transducers. Such systems could provide coupling between photons, spins and charges via phonons. It has recently been shown theoretically that optically trapped dielectric nanospheres could reach the ground state via sympathetic cooling with trapped cold atoms. This technique can be beneficial in cases where cryogenic operation of the oscillator is not practical. We describe experimental advances towards coupling an optically levitated dielectric nanosphere to a gas of cold Rubidium atoms. The sphere and the cold atoms are in separate vacuum chambers and are coupled using a one-dimensional optical lattice. This work is partially supported by NSF, Grant Nos. PHY-1205994,PHY-1506431.

  19. Synthesis of monodisperse crosslinked polystyrene microspheres

    Institute of Scientific and Technical Information of China (English)

    Jiang Kai; Chen Sheng-Li; Dong Peng; Liu Renxiao

    2008-01-01

    Monodisperse crosslinked polystyrene (CPS) particles were prepared through the normal emulsion polymerization method by adding crosslinker-divinylbenzene (DVB) into the reaction system after polystyrene (PS) particles grew to ~80% of the final size. When the amount of crosslinker DVB added was less than 6.17 wt% based on styrene, the prepared CPS particles were spherical and uniform and the size of the CPS particles could be predicted through the normal emulsion method. The glass transition temperature (Tg) of the prepared CPS particles was higher than that of un-crosslinked PS particles and, the more crosslinker that was added, the higher the Tg of CPS Particles. The prepared CPS particles had strong resistance to organic solvents.

  20. Monodisperse microdroplet generation and stopping without coalescence

    Energy Technology Data Exchange (ETDEWEB)

    Beer, Neil Reginald

    2016-02-23

    A system for monodispersed microdroplet generation and trapping including providing a flow channel in a microchip; producing microdroplets in the flow channel, the microdroplets movable in the flow channel; providing carrier fluid in the flow channel using a pump or pressure source; controlling movement of the microdroplets in the flow channel and trapping the microdroplets in a desired location in the flow channel. The system includes a microchip; a flow channel in the microchip; a droplet maker that generates microdroplets, the droplet maker connected to the flow channel; a carrier fluid in the flow channel, the carrier fluid introduced to the flow channel by a source of carrier fluid, the source of carrier fluid including a pump or pressure source; a valve connected to the carrier fluid that controls flow of the carrier fluid and enables trapping of the microdroplets.

  1. A Facile Strategy for In Situ Core-Template-Functionalizing Siliceous Hollow Nanospheres for Guest Species Entrapment

    Directory of Open Access Journals (Sweden)

    Weng Wenjian

    2009-01-01

    Full Text Available Abstract The shell wall-functionalized siliceous hollow nanospheres (SHNs with functional molecules represent an important class of nanocarriers for a rich range of potential applications. Herein, a self-templated approach has been developed for the synthesis of in situ functionalized SHNs, in which the biocompatible long-chain polycarboxylates (i.e., polyacrylate, polyaspartate, gelatin provide the framework for silica precursor deposition by simply controlling chain conformation with divalent metal ions (i.e., Ca2+, Sr2+, without the intervention of any external templates. Metal ions play crucial roles in the formation of organic vesicle templates by modulating the long chains of polymers and preventing them from separation by washing process. We also show that, by in situ functionalizing the shell wall of SHNs, it is capable of entrapping nearly an eightfold quantity of vitamin Bc in comparison to the bare bulk silica nanospheres. These results confirm the feasibility of guest species entrapment in the functionalized shell wall, and SHNs are effective carriers of guest (bio-molecules potentially for a variety of biomedical applications. By rationally choosing the functional (self-templating molecules, this concept may represent a general strategy for the production of functionalized silica hollow structures.

  2. Increase in stability of cellulase immobilized on functionalized magnetic nanospheres

    Science.gov (United States)

    Zhang, Wenjuan; Qiu, Jianhui; Feng, Huixia; Zang, Limin; Sakai, Eiichi

    2015-02-01

    Functionalized magnetic nanospheres were prepared by co-condensation of tetraethylorthosilicate with three different amino-silanes: 3-(2-aminoethylamino propyl)-triethoxysilane (AEAPTES), 3-(2-aminoethylamino propyl)-trimethoxysilane (AEAPTMES) and 3-aminopropyltriethoxysilane (APTES). Then three functionalized magnetic nanospheres were used as supports for immobilization of cellulase. The three functionalized magnetic nanospheres with core-shell morphologies exhibited higher capacity for cellulase immobilization than unfunctionalized magnetic nanospheres. The increasing of surface charge of functionalized magnetic nanospheres leads to an enhancement of the capacity of cellulase immobilization. Particularly, AEAPTMES with methoxy groups was favored to be hydrolyzed and grafted on unfunctionalized magnetic nanospheres than the others. AEAPTMES functionalized magnetic nanospheres with the highest zeta potential (29 mV) exhibited 87% activity recovery and the maximum amount of immobilized cellulase was 112 mg/g support at concentration of initial cellulase of 8 mg/mL. Immobilized cellulase on AEAPTMES functionalized magnetic nanospheres had higher temperature stability and broader pH stability than other immobilized cellulases and free cellulase. In particular, it can be used in about 40 °C, demonstrating the potential of biofuel production using this immobilized cellulase.

  3. Alginate Nanospheres Prepared by Internal or External Gelation with Nanoparticles

    NARCIS (Netherlands)

    Paques, J.P.

    2015-01-01

    Alginate is a biodegradable polymer that can be used for the formation of nanospheres with applications in food, biomedicine, and biotechnology. Alginate gels in mild conditions, and does not require organic solvents for the formation of nanospheres. This makes them ideal for entrapment of sensitive

  4. Alginate Nanospheres Prepared by Internal or External Gelation with Nanoparticles

    NARCIS (Netherlands)

    Paques, J.P.

    2015-01-01

    Alginate is a biodegradable polymer that can be used for the formation of nanospheres with applications in food, biomedicine, and biotechnology. Alginate gels in mild conditions, and does not require organic solvents for the formation of nanospheres. This makes them ideal for entrapment of sensitive

  5. Synthesis and characterization of monodispersed inorganic/organic core/shell microspheres with fluorescence

    Institute of Scientific and Technical Information of China (English)

    ZHANG Kai; HAN Kun; ZHANG Xuehai; YANG Bai

    2005-01-01

    @@ In recent years, the semiconductor nanocrystals (NCs) have attracted great interest due to their potentials in photonics, electronics, magnetics and catalysis, and the monodispersed organic or inorganic microspheres doped NCs display predominant characteristics in the fabrication and study for photonic crystals[1,2], and considerable effort has been devoted to the design and synthesis of CdTe NCs doped colloid with well fluorescence[3-8]. For example, CdTe NCs were fabricated on the surfaces of silica or polymer microspheres by the methods of layer-by-layer assembly, and CdTe NCs were also doped into inorganic or organic microspheres through sol-gel process or swell- ing.

  6. Characterization of bismuth nanospheres deposited by plasma focus device

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, M., E-mail: cscientific2@aec.org.sy [IBA Laboratory, Chemistry Department, Atomic Energy Commission of Syria, P.O. Box 6091, Damascus (Syrian Arab Republic); Al-Hawat, Sh.; Akel, M. [Physics Department, Atomic Energy Commission of Syria, P.O. Box 6091, Damascus (Syrian Arab Republic); Mrad, O. [Chemistry Department, Atomic Energy Commission of Syria, P.O. Box 6091, Damascus (Syrian Arab Republic)

    2015-02-14

    A new method for producing thin layer of bismuth nanospheres based on the use of low energy plasma focus device is demonstrated. Various techniques such as scanning electron microscopy, Rutherford backscattering spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and Raman spectroscopy have been used to characterize the morphology and the composition of the nanospheres. Experimental parameters may be adjusted to favour the formation of bismuth nanospheres instead of microspheres. Therefore, the formation of large surface of homogeneous layer of bismuth nanospheres with sizes of below 100 nm can be obtained. The natural snowball phenomenon is observed to be reproduced in nanoscale where spheres roll over the small nanospheres and grow up to bigger sizes that can reach micro dimensions. The comet-like structure, a reverse phenomenon to snowball is also observed.

  7. Designing large scale chiral metamaterials by nanosphere shadowing lithography

    Science.gov (United States)

    He, Yizhuo; Zhao, Yiping

    2016-09-01

    A scalable nanofabrication technique for chiral metamaterials is presented, which combines the dynamic shadowing growth and self-assembled nanosphere monolayers, and is also known as nanosphere shadowing lithography. We have developed two strategies based on nanosphere shadowing lithography to prepare chiral nanostructures. The first strategy is to create a quasi-three-dimensional single-layer fan-shaped chiral nanostructure on nanospheres with one plasmonic material. The second strategy is to create three-dimensional multi-layers helical nanostructures with one plasmonic material and one dielectric material. Both strategies can produce large-area chiral nanostructures with strong chiral optical response, which makes nanosphere shadowing lithography suitable for producing chiral metamaterial based devices such as an ultrathin narrow-band circular polarizer.

  8. Toxicity of silica nanoparticles and the effect of protein corona

    DEFF Research Database (Denmark)

    Foldbjerg, Rasmus; Jespersen, Lars Vesterby; Wang, Jing

    2010-01-01

    ). The NPs were characterized by TEM and DLS as monodisperse and non-aggregated in solution and the NP suspensions were free of metal and endotoxin impurities as tested by ICP-MS and the LAL test. Cellular uptake and binding of the silica NPs was indirectly assessed by flow cytometry side scatter and SEM...... the NPs were found to cause increased cellular ROS production which could not be reduced by antioxidant treatment. In conclusion, our data suggest that surface area is an appropriate dose metric to predict cytotoxicity and inflammation induced by silica nanoparticles. Furthermore, the reduced toxicity...

  9. The contribution of polystyrene nanospheres towards the crystallization of proteins.

    Directory of Open Access Journals (Sweden)

    Johanna M Kallio

    Full Text Available BACKGROUND: Protein crystallization is a slow process of trial and error and limits the amount of solved protein structures. Search of a universal heterogeneous nucleant is an effort to facilitate crystallizability of proteins. METHODOLOGY: The effect of polystyrene nanospheres on protein crystallization were tested with three commercial proteins: lysozyme, xylanase, xylose isomerase, and with five research target proteins: hydrophobins HFBI and HFBII, laccase, sarcosine dimethylglycine N-methyltransferase (SDMT, and anti-testosterone Fab fragment 5F2. The use of nanospheres both in screening and as an additive for known crystallization conditions was studied. In screening, the addition of an aqueous solution of nanosphere to the crystallization drop had a significant positive effect on crystallization success in comparison to the control screen. As an additive in hydrophobin crystallization, the nanospheres altered the crystal packing, most likely due to the amphiphilic nature of hydrophobins. In the case of laccase, nanospheres could be used as an alternative for streak-seeding, which insofar had remained the only technique to produce high-diffracting crystals. With methyltransferase SDMT the nanospheres, used also as an additive, produced fewer, larger crystals in less time. Nanospheres, combined with the streak-seeding method, produced single 5F2 Fab crystals in shorter equilibration times. CONCLUSIONS: All in all, the use of nanospheres in protein crystallization proved to be beneficial, both when screening new crystallization conditions to promote nucleation and when used as an additive to produce better quality crystals, faster. The polystyrene nanospheres are easy to use, commercially available and close to being inert, as even with amphiphilic proteins only the crystal packing is altered and the nanospheres do not interfere with the structure and function of the protein.

  10. Magnetic Films on Self-assembled Nanospheres

    Institute of Scientific and Technical Information of China (English)

    T.Ulbrich; I.Guhr; T.Schrefl; O.Hellwig; S.van; Dijken; M.Albrecht

    2007-01-01

    1 Results Nanoparticle media using arrays of monodisperse nanoparticles with high magneticanisotropy are assumed to be the ideal future magnetic recording media. However,key requirements like control of the magnetic anisotropy orientation along with magnetic domain isolation have not been achieved so far. Here, we report on a combination of a two-dimensional topographic pattern formed of self-assembled nanoparticles with sizes as small as 20 nm and magnetic multilayer film deposition[1]. The so formed n...

  11. Hollow Nanospheres with Fluorous Interiors for Transport of Molecular Oxygen in Water

    KAUST Repository

    Vu, Khanh B.

    2016-08-11

    A dispersion system for saturated fluorocarbon (SFC) liquids based on permeable hollow nanospheres with fluorous interiors is described. The nanospheres are well dispersible in water and are capable of immediate uptake of SFCs. The nanosphere shells are gas-permeable and feature reactive functional groups for easy modification of the exterior. These features make the SFC-filled nanospheres promising vehicles for respiratory oxygen storage and transport. Uptake of molecular oxygen into nanosphere-stabilized SFC dispersions is demonstrated.

  12. Fabrication of parabolic Si nanostructures by nanosphere lithography and its application for solar cells.

    Science.gov (United States)

    Cheon, See-Eun; Lee, Hyeon-Seung; Choi, Jihye; Jeong, Ah Reum; Lee, Taek Sung; Jeong, Doo Seok; Lee, Kyeong-Seok; Lee, Wook-Seong; Kim, Won Mok; Lee, Heon; Kim, Inho

    2017-08-04

    We demonstrated fabrication of a parabola shaped Si nanostructures of various periods by combined approach of nanosphere lithography and a single step CF4/O2 reactive ion etch (RIE) process. Silica nanosphere monolayers in a hexagonal array were well deposited by a solvent controlled spin coating technique based on binary organic solvents. We showed numerically that a parabolic Si nanostructure of an optimal period among various-shaped nanostructures overcoated with a dielectric layer of a 70 nm thickness provide the most effective antireflection. As the simulation results as a design guide, we fabricated the parabolic Si nanostructures of a 520 nm period and a 300 nm height exhibiting the lowest weighted reflectance of 2.75%. With incorporation of such parabolic Si nanostructures, a damage removal process for 20 sec and SiNx antireflection coating of a 70 nm thickness, the efficiency of solar cells increased to 17.2% while that of the planar cells without the nanostructures exhibited 16.2%. The efficiency enhancement of the cell with the Si nanostructures was attributed to the improved photocurrents arising from the broad spectral antireflection which was confirmed by the external quantum efficiency (EQE) measurements.

  13. Mesoporous transition metal oxides quasi-nanospheres with enhanced electrochemical properties for supercapacitor applications.

    Science.gov (United States)

    Wang, Lu; Duan, Guorong; Zhu, Junwu; Chen, Shen-Ming; Liu, Xiao-Heng; Palanisamy, Selvakumar

    2016-12-01

    In this report, we obtain mesoporous transition metal oxides quasi-nanospheres (includes MnO2, NiO, and Co3O4) by utilizing mesoporous silica nanospheres as a template for high-performance supercapacitor electrodes. All samples have a large specific surface area of approximately 254-325m(2)g(-1) and a relatively narrow pore size distribution in the region of 7nm. Utilization of a nanosized template resulted in a product with a relative uniform morphology and a small particle diameter in the region of 50-100nm. As supercapacitor electrodes, MnO2, NiO, and Co3O4 exhibit an outstanding capacity as high as 838-1185Fg(-1) at 0.5Ag(-1) and a superior long-term stability with minimal loss of 3-7% after 6000 cycles at 1Ag(-1). Their excellent electrochemical performances are attributed to favorable morphologies with a large surface area and a uniform architecture with abundant pores. The associated enhancement of electrolyte ion circulation within the electrode facilitates a significant increase in availability of Faradic reaction electroactive sites.

  14. Water evaporation in silica colloidal deposits.

    Science.gov (United States)

    Peixinho, Jorge; Lefèvre, Grégory; Coudert, François-Xavier; Hurisse, Olivier

    2013-10-15

    The results of an experimental study on the evaporation and boiling of water confined in the pores of deposits made of mono-dispersed silica colloidal micro-spheres are reported. The deposits are studied using scanning electron microscopy, adsorption of nitrogen, and adsorption of water through attenuated total reflection-infrared spectroscopy. The evaporation is characterized using differential scanning calorimetry and thermal gravimetric analysis. Optical microscopy is used to observe the patterns on the deposits after evaporation. When heating at a constant rate and above boiling temperature, the release of water out of the deposits is a two step process. The first step is due to the evaporation and boiling of the surrounding and bulk water and the second is due to the desorption of water from the pores. Additional experiments on the evaporation of water from membranes having cylindrical pores and of heptane from silica deposits suggest that the second step is due to the morphology of the deposits.

  15. Porphyrin coordination polymer nanospheres and nanorods

    Science.gov (United States)

    Wang, Zhongchun; Shelnutt, John A.; Medforth, Craig J.

    2012-12-04

    A porphyrin coordination polymer nanostructure comprising a network of pyridyl porphyrin molecules and coordinating metal ions coordinatively bound through the pyridyl groups. In some embodiments, the porphyrins are metalloporphyrins. A variety of nanostructures are formed by the network polymer, including nanospheres, polygonal nanostructures, nanorods, and nanofibers, depending on a variety of factors including coordination metal ion, porphyrin type, metal of the metalloporphyrin, and degree of agitation during nanostructure formation. Reduction of coordinating metal ions may be used to form metal nanoparticles on the coordination polymer nanostructure.

  16. Atomistic deformation mechanisms in twinned copper nanospheres.

    Science.gov (United States)

    Bian, Jianjun; Niu, Xinrui; Zhang, Hao; Wang, Gangfeng

    2014-01-01

    In the present study, we perform molecular dynamic simulations to investigate the compression response and atomistic deformation mechanisms of twinned nanospheres. The relationship between load and compression depth is calculated for various twin spacing and loading directions. Then, the overall elastic properties and the underlying plastic deformation mechanisms are illuminated. Twin boundaries (TBs) act as obstacles to dislocation motion and lead to strengthening. As the loading direction varies, the plastic deformation transfers from dislocations intersecting with TBs, slipping parallel to TBs, and then to being restrained by TBs. The strengthening of TBs depends strongly on the twin spacing.

  17. Porphyrin coordination polymer nanospheres and nanorods

    Science.gov (United States)

    Wang, Zhongchun; Shelnutt, John A.; Medforth, Craig J.

    2013-09-10

    A porphyrin coordination polymer nanostructure comprising a network of pyridyl porphyrin molecules and coordinating metal ions coordinatively bound through the pyridyl groups. In some embodiments, the porphyrins are metalloporphyrins. A variety of nanostructures are formed by the network polymer, including nanospheres, polygonal nanostructures, nanorods, and nanofibers, depending on a variety of factors including coordination metal ion, porphyrin type, metal of the metalloporphyrin, and degree of agitation during nanostructure formation. Reduction of coordinating metal ions may be used to form metal nanoparticles on the coordination polymer nanostructure.

  18. Formation of AgGaS2 nano-pyramids from Ag2S nanospheres through intermediate Ag2S-AgGaS2 heterostructures and AgGaS2 sensitized Mn2+ emission

    Science.gov (United States)

    Huang, Feng; Zhou, Jiangcong; Xu, Ju; Wang, Yuansheng

    2014-01-01

    A one-pot solution synthesis of monodisperse AgGaS2 nanocrystals with uniform pyramid-like shape is realized for the first time, in which an interesting phase and shape evolution from monodisperse Ag2S nanospheres to pure AgGaS2 nano-pyramids through an intermediate stage of Ag2S-AgGaS2 heterostructures, is revealed. Evidently, upon introducing Mn2+ ions into the reaction system, they are incorporated into AgGaS2 nano-pyramids which act as efficient sensitization matrixes for the red emission of Mn2+ d-d transition under blue excitation. Benefiting from their non-toxicity and facile fabrication, Mn:AgGaS2 nanocrystals may find potential applications in some fields such as blue chip excited LEDs and bio-labeling.A one-pot solution synthesis of monodisperse AgGaS2 nanocrystals with uniform pyramid-like shape is realized for the first time, in which an interesting phase and shape evolution from monodisperse Ag2S nanospheres to pure AgGaS2 nano-pyramids through an intermediate stage of Ag2S-AgGaS2 heterostructures, is revealed. Evidently, upon introducing Mn2+ ions into the reaction system, they are incorporated into AgGaS2 nano-pyramids which act as efficient sensitization matrixes for the red emission of Mn2+ d-d transition under blue excitation. Benefiting from their non-toxicity and facile fabrication, Mn:AgGaS2 nanocrystals may find potential applications in some fields such as blue chip excited LEDs and bio-labeling. Electronic supplementary information (ESI) available: Fig. S1-S2. See DOI: 10.1039/c3nr04765b

  19. Sonochemical synthesis of silica particles and their size control

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hwa-Min [Advanced Materials and Chemical Engineering, Catholic University of Daegu, Gyeongbuk 38430 (Korea, Republic of); Lee, Chang-Hyun [Electronic and Electrical Engineering, Catholic University of Daegu, Gyeongbuk 38430 (Korea, Republic of); Kim, Bonghwan, E-mail: bhkim@cu.ac.kr [Electronic and Electrical Engineering, Catholic University of Daegu, Gyeongbuk 38430 (Korea, Republic of)

    2016-09-01

    Graphical abstract: - Highlights: • Silica particles were easily prepared by an ultrasound-assisted sol–gel method. • The particle size was controlled by the ammonium hydroxide/water molar ratio. • The size-controlled diameter of silica particles ranged from 40 to 400 nm. • The particles were formed in a relatively short reaction time. - Abstract: Using an ultrasound-assisted sol–gel method, we successfully synthesized very uniformly shaped, monodisperse, and size-controlled spherical silica particles from a mixture of ethanol, water, and tetraethyl orthosilicate in the presence of ammonia as catalyst, at room temperature. The diameters of the silica particles were distributed in the range from 40 to 400 nm; their morphology was well characterized by scanning electron microscopy. The silica particle size could be adjusted by choosing suitable concentrations of ammonium hydroxide and water, which in turn determined the nucleation and growth rates of the particles during the reaction. This sonochemical-based silica synthesis offers an alternative way to produce spherical silica particles in a relatively short reaction time. Thus, we suggest that this simple, low-cost, and efficient method of preparing uniform silica particles of various sizes will have practical and wide-ranging industrial applicability.

  20. Core–shell nanospheres Pt@SiO{sub 2} for catalytic hydrogen production

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Yujuan; Wang, Yuqing; Lu, Zhang-Hui, E-mail: luzh@jxnu.edu.cn; Chen, Xiangshu, E-mail: cxs66cn@jxnu.edu.cn; Xiong, Lihua

    2015-06-30

    Highlights: • Pt@SiO{sub 2} core–shell NPs are synthesized via a simple one-pot synthetic route. • Ultrafine Pt NPs (∼4 nm) are embedded in well-proportioned SiO{sub 2} nanospheres. • Pt@SiO{sub 2} shows a high activity and good durability for H{sub 2} generation from AB. - Abstract: Ultrafine platinum nanoparticles (NPs) embedded in silica nanospheres (Pt@SiO{sub 2}) have been synthesized in a NP-5/cyclohexane reversed-micelle system followed by NaBH{sub 4} reduction. The as-synthesized core–shell nanocatalysts Pt@SiO{sub 2} were characterized by scanning electron microscopy, transmission electron microscopes, X-ray powder diffraction analysis, energy dispersive X-ray spectrometer and nitrogen adsorption–desorption investigations. Interestingly, the as-synthesized core–shell nanocatalysts Pt@SiO{sub 2} showed an excellent catalytic performance in hydrogen generation from the hydrolysis of ammonia borane (BH{sub 3}NH{sub 3}, AB) at room temperature. Especially, the catalytic performance of the Pt@SiO{sub 2} remained almost unchanged after the five recycles and even after the heat treatment (673 K), because the silica shells inhibit aggregation or deformation of the metal cores. Besides, the kinetic studies showed that the catalytic hydrolysis of AB was first order with respect to the catalyst concentration and zero order with respect to the substrate concentration, respectively. The excellent catalytic activity and stability of Pt@SiO{sub 2} can make it have a bright future in the practical application.

  1. Preparation, Properties, and Self-Assembly Behavior of PTFE-Based Core-Shell Nanospheres

    Directory of Open Access Journals (Sweden)

    Katia Sparnacci

    2012-01-01

    Full Text Available Nanosized PTFE-based core-shell particles can be prepared by emulsifier-free seed emulsion polymerization technique starting from spherical or rod-like PTFE seeds of different size. The shell can be constituted by the relatively high Tg polystyrene and polymethylmethacrylate as well as by low Tg polyacrylic copolymers. Peculiar thermal behavior of the PTFE component is observed due to the high degree of PTFE compartmentalization. A very precise control over the particle size can be exerted by properly adjusting the ratio between the monomers and the PTFE seed. In addition, the particle size distribution self-sharpens as the ratio monomer/PTFE increases. Samples with uniformity ratios suited to build 2D and 3D colloidal crystals are easily prepared. In particular, 2D colloidal crystal of spheres leads to very small 2D nanostructuration, useful for the preparation of masks with a combination of nanosphere lithography and reactive ion etching. 3D colloidal crystals were also obtained featuring excellent opal quality, which is a direct consequence of the monodispersity of colloids used for their growth.

  2. Facile synthesis of oxidic PEG-modified magnetic polydopamine nanospheres for Candida rugosa lipase immobilization.

    Science.gov (United States)

    Hou, Chen; Zhu, Hao; Li, Yanfeng; Li, Yijing; Wang, Xinyu; Zhu, Weiwei; Zhou, Rongde

    2015-02-01

    A versatile method for the design of polydopamine-coated magnetic material with a brush-like structure used for Candida Rugosa lipase (CRL) immobilization was reported in this work. First, polydopamine (PDA) was coated on the surface of Fe₃O₄ nanospheres (Fe₃O₄ NPs) with a controllable thickness via dip coating process, and CRL can be immobilized on it directly via covalent bonding. Subsequently, PDA-functionalized Fe₃O₄ NPs were modified with dialdehyde polyethylene glycol (PEG) to obtain the aldehyde groups, and the brush-like structure of the magnetic supports was formed. After being characterized with various methods, it was verified that the prepared magnetic NPs possessed good monodispersity and displayed high saturation magnetization after modification. Meanwhile, the CRL was immobilized on it covalently, and the enzyme activities such as activity, stability, and reusability were investigated. Significantly, the versatility of polydopamine-inspired chemistry combined with the unique biological nature and tunability with dialdehyde PEG could evoke the efficiency of the CRL, making this a promising coating technique for various bio-applications.

  3. Photochromic silver nanoparticles fabricated by nanosphere lithography

    Energy Technology Data Exchange (ETDEWEB)

    Meixner, Melanie; Sprafke, Alexander; Hallermann, Florian; Reismann, Maximilian; Wuttig, Matthias; Plessen, Gero von [Institute of Physics, RWTH Aachen University, 52056 Aachen (Germany)

    2009-07-01

    Photochromic materials change their color under irradiation with light. In previous work, we have studied the photochromic transformation of silver nanoparticles embedded in transition-metal oxides prepared by dc-sputter deposition, such as TiO{sub x}, ZrO{sub x} and HfO{sub x}. The silver nanoparticles are highly inhomogeneous in shape, size and spatial distribution. The photochromic effect is based on spectral hole burning in the inhomogeneously broadened particle-plasmon band. This hole burning is probably caused by photoemission of electrons from the resonantly excited particles. In the present work, we show that TiO{sub x}-embedded silver nanoparticles with improved photochromic properties can be fabricated through a combination of electron-beam evaporation and nanosphere lithography. Nanosphere lithography is a method to produce hexagonal arranged and equally shaped particles. The good reproducibility of this approach allows us to analyze the photochromic transformation in a more quantitative way than was possible with samples prepared by sputter deposition.

  4. Rapid enumeration of phage in monodisperse emulsions.

    Science.gov (United States)

    Tjhung, Katrina F; Burnham, Sean; Anany, Hany; Griffiths, Mansel W; Derda, Ratmir

    2014-06-17

    Phage-based detection assays have been developed for the detection of viable bacteria for applications in clinical diagnosis, monitoring of water quality, and food safety. The majority of these assays deliver a positive readout in the form of newly generated progeny phages by the bacterial host of interest. Progeny phages are often visualized as plaques, or holes, in a lawn of bacteria on an agar-filled Petri dish; however, this rate-limiting step requires up to 12 h of incubation time. We have previously described an amplification of bacteriophages M13 inside droplets of media suspended in perfluorinated oil; a single phage M13 in a droplet yields 10(7) copies in 3-4 h. Here, we describe that encapsulation of reporter phages, both lytic T4-LacZ and nonlytic M13, in monodisperse droplets can also be used for rapid enumeration of phage. Compartmentalization in droplets accelerated the development of the signal from the reporter enzyme; counting of "positive" droplets yields accurate enumeration of phage particles ranging from 10(2) to 10(6) pfu/mL. For enumeration of T4-LacZ phage, the fluorescent signal appeared in as little as 90 min. Unlike bulk assays, quantification in emulsion is robust and insensitive to fluctuations in environmental conditions (e.g., temperature). Power-free emulsification using gravity-driven flow in the absence of syringe pumps and portable fluorescence imaging solutions makes this technology promising for use at the point of care in low-resource environments. This droplet-based phage enumeration method could accelerate and simplify point-of-care detection of the pathogens for which reporter bacteriophages have been developed.

  5. Synthesis, characterization and properties of hollow nickel phosphide nanospheres

    Energy Technology Data Exchange (ETDEWEB)

    Ni Yonghong; Tao Ali; Hu Guangzhi; Cao Xiaofeng; Wei Xianwen; Yang Zhousheng [College of Chemistry and Materials Science, Anhui Key Laboratory of Functional Molecular Solids, Anhui Normal University, Wuhu 241000 (China)

    2006-10-14

    Nickel phosphide (Ni{sub 12}P{sub 5}) hollow nanospheres with a mean diameter of 100 nm and a shell thickness of 15-20 nm have been successfully prepared by a hydrothermal-microemulsion route, using NaH{sub 2}PO{sub 2} as a phosphorus source. XRD, EDS (HR)TEM, SEM and the SAED pattern were used to characterize the final product. Experiments showed that the as-prepared nickel phosphide hollow nanospheres could selectively catalytically degrade some organic dyes such as methyl red and Safranine T under 254 nm UV light irradiation. At the same time, the nickel phosphide hollow nanospheres showed a stronger ability to promote electron transfer between the glass-carbon electrode and adrenalin than nickel phosphide honeycomb-like particles prepared by a simple hydrothermal route. A possible formation process for nickel phosphide hollow nanospheres was suggested based on the experimental results.

  6. Irregular shaping of polystyrene nanosphere array by plasma etching

    National Research Council Canada - National Science Library

    Luo, Hao; Liu, Tingting; Ma, Jun; Wang, Wei; Li, Heng; Wang, Pengwei; Bai, Jintao; Jing, Guangyin

    2013-01-01

    .... Here, by plasma etching, the controllable tailoring of the nanosphere is realized and its morphology dependence on the initial shape, microscopic roughness, and the etching conditions is investigated quantitatively...

  7. Adsorption of Organophosphate Pesticide Dimethoate on Gold Nanospheres and Nanorods

    Directory of Open Access Journals (Sweden)

    Tatjana Momić

    2016-01-01

    Full Text Available Organophosphorus pesticide dimethoate was adsorbed onto gold nanospheres and nanorods in aqueous solution using batch technique. Adsorption of dimethoate onto gold nanoparticles was confirmed by UV-Vis spectrophotometry, TEM, AFM, and FTIR analysis. The adsorption of nanospheres resulted in aggregation which was not the case with nanorods. Nanoparticles adsorption features were characterized using Langmuir and Freundlich isotherm models. The Langmuir adsorption isotherm was found to have the best fit to the experimental data for both types of nanoparticles. Adsorption capacity detected for nanospheres is 456 mg/g and for nanorods is 57.1 mg/g. Also, nanoparticles were successfully used for dimethoate removal from spiked drinking water while nanospheres were shown to be more efficient than nanorods.

  8. Adsorption of Organophosphate Pesticide Dimethoate on Gold Nanospheres and Nanorods

    OpenAIRE

    Tatjana Momić; Tamara Lazarević Pašti; Una Bogdanović; Vesna Vodnik; Ana Mraković; Zlatko Rakočević; Pavlović, Vladimir B.; Vesna Vasić

    2016-01-01

    Organophosphorus pesticide dimethoate was adsorbed onto gold nanospheres and nanorods in aqueous solution using batch technique. Adsorption of dimethoate onto gold nanoparticles was confirmed by UV-Vis spectrophotometry, TEM, AFM, and FTIR analysis. The adsorption of nanospheres resulted in aggregation which was not the case with nanorods. Nanoparticles adsorption features were characterized using Langmuir and Freundlich isotherm models. The Langmuir adsorption isotherm was found to have the ...

  9. Growth Kinetics of Monodisperse Polystyrene Microspheres Prepared by Dispersion Polymerization

    Directory of Open Access Journals (Sweden)

    Fan Li

    2013-01-01

    Full Text Available Dispersion polymerization has been widely applied to the synthesis of monodisperse micron-sized polymer colloidal spheres. Many efforts have been devoted to studying the influence of initial conditions on the size and uniformity of the resultant microspheres, aiming to synthesize micron-size monodisperse colloidal spheres. However, the inner contradiction between the size and the size distribution of colloidal spheres hinders the realization of this goal. In this work, we drew our attention from the initial conditions to the growth stage of dispersion polymerization. We tracked the size evolution of colloidal sphere during the dispersion polymerization, through which we established a kinetic model that described the relationship between the monomer concentration and the reaction time. The model may provide a guideline to prepare large polymer colloidal spheres with good monodispersity by continuous monomer feeding during the growth stage to maintain the concentration of monomer at a constant value in a dispersion polymerization process.

  10. Controlling the Geometries of Si Nanowires through Tunable Nanosphere Lithography.

    Science.gov (United States)

    Li, Luping; Fang, Yin; Xu, Cheng; Zhao, Yang; Wu, Kedi; Limburg, Connor; Jiang, Peng; Ziegler, Kirk J

    2017-02-14

    A tunable nanosphere lithography (NSL) technique is combined with metal-assisted etching of silicon (Si) to fabricate ordered, high-aspect-ratio Si nanowires. Non-close-packed structures are directly prepared via shear-induced ordering of the nanospheres. The spacing between the nanospheres is independent of their diameters and tuned by changing the loading of nanospheres. Nanowires with spacings between 110 and 850 nm are easily achieved with diameters between 100 and 550 nm. By eliminating plasma or heat treatment of the nanospheres, the diameter of the nanowires fabricated is nearly identical to the nanosphere diameter in the suspension. The elimination of this step helps avoid common drawbacks of traditional NSL approaches, leading to the high-fidelity, large-scale fabrication of highly crystalline, nonporous Si nanowires in ordered hexagonal patterns. The ability to simultaneously control the diameter and spacing makes the NSL technique more versatile and expands the range of geometries that can be fabricated by top-down approaches.

  11. Antioxidative and antiinflammatory activities of quercetin-loaded silica nanoparticles.

    Science.gov (United States)

    Lee, Ga Hyun; Lee, Sung June; Jeong, Sang Won; Kim, Hyun-Chul; Park, Ga Young; Lee, Se Geun; Choi, Jin Hyun

    2016-07-01

    Utilizing the biological activities of compounds by encapsulating natural components in stable nanoparticles is an important strategy for a variety of biomedical and healthcare applications. In this study, quercetin-loaded silica nanoparticles were synthesized using an oil-in-water microemulsion method, which is a suitable system for producing functional nanoparticles of controlled size and shape. The resulting quercetin-loaded silica nanoparticles were spherical, highly monodispersed, and stable in an aqueous system. Superoxide radical scavenging effects were found for the quercetin-loaded silica nanoparticles as well as free quercetin. The quercetin-loaded silica nanoparticles showed cell viability comparable to that of the controls. The amounts of proinflammatory cytokines produced by macrophages, such as interleukin 1 beta, interleukin 6, and tumor necrosis factor alpha, were reduced significantly for the quercetin-loaded silica nanoparticles. These results suggest that the antioxidative and antiinflammatory activities of quercetin are maintained after encapsulation in silica. Silica nanoparticles can be used for the effective and stable incorporation of biologically active natural components into composite biomaterials.

  12. Microscopic versus macroscopic calculation of dielectric nanospheres

    Science.gov (United States)

    Kühn, M.; Kliem, H.

    2008-12-01

    The issue of nanodielectrics has recently become an important field of interest. The term describes nanometric dielectrics, i. e. dielectric materials with structural dimensions typically smaller than 100 run. In contrast to the behaviour of a bulk material the nanodielectrics can behave completely different. With shrinking dimensions the surface or rather boundary effects outweigh the volume effects. This leads to a different observable physics at the nanoscale. A crucial point is the question whether a continuum model for the calculation of dielectric properties is still applicable for these nanomaterials. In order to answer this question we simulated dielectric nanospheres with a microscopic local field method and compared the results to the macroscopic mean field theory.

  13. Screening of a model for the distribution of dye in dye-encapsulated silica through the gradual etching of the outermost silica layer using hydrofluoric acid.

    Science.gov (United States)

    Wi, Rinbok; Lee, Kyoung G; Yoon, Sun Hong; Lee, Sang Geun; Imran, Muhammad; Kim, Do Hyun

    2011-07-01

    Monodispersed spherical silica particles emitting blue light were prepared by incorporating 2,5-bis(5-tert-butyl-2-benzoxazolyl)thiophene (BBOT) into a silica matrix. The morphological and photoluminescent properties were investigated to confirm the proper incorporation of BBOT into the silica matrix, using an electron microscope and a fluorescence spectrometer. Four possible models representing the distribution of the dye molecules in a dye-encapsulated silica particle were proposed. To analyze the distribution of the BBOT dye in the BBOT-encapsulated silica, the fluorescent emission intensity was measured while reducing the particle diameter by etching the outermost silica layer with hydrofluoric acid with 0-0.5 wt.% concentrations. The distribution of BBOT in a silica particle was investigated based on the relationship between the changes in particle diameter and the changes in emission intensity. The emission intensity of the BBOT-encapsulated silica particle oscillated with the decreasing particle diameter. This result supported the multilayered model. Information regarding the distribution of the dye in the silica matrix will provide valuable information for understanding the formation mechanism of dye-encapsulated silica.

  14. Preparation of spherical ceria coated silica nanoparticle abrasives for CMP application

    Energy Technology Data Exchange (ETDEWEB)

    Peedikakkandy, Lekha [Department of Metallurgical Engineering and Materials Science, IIT Bombay, Powai, Mumbai 400076 (India); Kalita, Laksheswar [Advanced Technology Group, Applied Materials India Pvt. Ltd., Department of Electrical Engineering, IIT Bombay, Powai, Mumbai 400076 (India); Kavle, Pravin [Department of Metallurgical Engineering and Materials Science, IIT Bombay, Powai, Mumbai 400076 (India); Kadam, Ankur; Gujar, Vikas; Arcot, Mahesh [Advanced Technology Group, Applied Materials India Pvt. Ltd., Department of Electrical Engineering, IIT Bombay, Powai, Mumbai 400076 (India); Bhargava, Parag, E-mail: pbhargava@iitb.ac.in [Department of Metallurgical Engineering and Materials Science, IIT Bombay, Powai, Mumbai 400076 (India)

    2015-12-01

    Highlights: • Nano-layer coating of ceria over silica nanoparticles. • Study effect of reaction pH and temperature on ceria coating over silica nanoparticles. • CMP application of ceria coated silica nanoparticles over SiO{sub 2} and SiN films. - Abstract: This paper describes synthesis of spherical and highly mono-dispersed ceria coated silica nanoparticles of size ∼70–80 nm for application as abrasive particles in Chemical Mechanical Planarization (CMP) process. Core silica nanoparticles were initially synthesized using micro-emulsion method. Ceria coating on these ultrafine and spherical silica nanoparticles was achieved using controlled chemical precipitation method. Study of various parameters influencing the formation of ceria coated silica nanoparticles of size less than 100 nm has been undertaken and reported. Ceria coating over silica nanoparticles was varied by controlling the reaction temperature, pH and precursor concentrations. Characterization studies using X-ray diffraction, scanning electron microscopy, transmission electron microscopy and Energy Dispersive X-ray analysis show formation of crystalline CeO{sub 2} coating of ∼10 nm thickness over silica with spherical morphology and particle size <100 nm. Aqueous slurry of ceria coated silica abrasive was prepared and employed for polishing of oxide and nitride films on silicon substrates. Polished films were studied using ellipsometry and an improvement in SiO{sub 2}:SiN selective removal rates up to 12 was observed using 1 wt% ceria coated silica nanoparticles slurry.

  15. Observation of a shape-dependent density maximum in random prackigns and glasses of colloidal silica ellipsoids

    NARCIS (Netherlands)

    Sacanna, S.; Rossi, L.; Wouterse, A.; Philipse, A.P.

    2007-01-01

    We have measured the random packing density of monodisperse colloidal silica ellipsoids with a well-defined shape, gradually deviating from a sphere shape up to prolates with aspect ratios of about 5, to find for a colloidal system the first experimental observation for the density maximum (at an as

  16. Multipod-like silica/polystyrene clusters

    Science.gov (United States)

    Désert, Anthony; Morele, Jérémy; Taveau, Jean-Christophe; Lambert, Olivier; Lansalot, Muriel; Bourgeat-Lami, Elodie; Thill, Antoine; Spalla, Olivier; Belloni, Luc; Ravaine, Serge; Duguet, Etienne

    2016-03-01

    Multipod-like clusters composed of a silica core and PS satellites are prepared according to a seeded-growth emulsion polymerization of styrene in the presence of size-monodisperse silica particles previously surface-modified with methacryloxymethyltriethoxysilane. Tuning the diameter and concentration of the silica seeds affords homogeneous batches of tetrapods, hexapods, octopods, nonapods and dodecapods with morphology yields as high as 80%. Three-dimensional reconstructions by cryo-electron tomography are presented on large fields for the first time to show the high symmetry and regularity of the clusters demonstrating the good control of the synthesis process. These synthesis experiments are visited again digitally, in order to successfully refine an original simulation model and better understand the correlation between the history of the cluster growth and the final composition of the cluster mixture. Finally, using the model as a predictive tool and varying the extra experimental conditions, e.g. the composition of the surfactant mixture and the styrene concentration, result in trapping other cluster morphologies, such as tripods.Multipod-like clusters composed of a silica core and PS satellites are prepared according to a seeded-growth emulsion polymerization of styrene in the presence of size-monodisperse silica particles previously surface-modified with methacryloxymethyltriethoxysilane. Tuning the diameter and concentration of the silica seeds affords homogeneous batches of tetrapods, hexapods, octopods, nonapods and dodecapods with morphology yields as high as 80%. Three-dimensional reconstructions by cryo-electron tomography are presented on large fields for the first time to show the high symmetry and regularity of the clusters demonstrating the good control of the synthesis process. These synthesis experiments are visited again digitally, in order to successfully refine an original simulation model and better understand the correlation between the

  17. Photoluminescence mechanisms of metallic Zn nanospheres, semiconducting ZnO nanoballoons, and metal-semiconductor Zn/ZnO nanospheres

    Science.gov (United States)

    Lin, Jin-Han; Patil, Ranjit A.; Devan, Rupesh S.; Liu, Zhe-An; Wang, Yi-Ping; Ho, Ching-Hwa; Liou, Yung; Ma, Yuan-Ron

    2014-01-01

    We utilized a thermal radiation method to synthesize semiconducting hollow ZnO nanoballoons and metal-semiconductor concentric solid Zn/ZnO nanospheres from metallic solid Zn nanospheres. The chemical properties, crystalline structures, and photoluminescence mechanisms for the metallic solid Zn nanospheres, semiconducting hollow ZnO nanoballoons, and metal-semiconductor concentric solid Zn/ZnO nanospheres are presented. The PL emissions of the metallic Zn solid nanospheres are mainly dependent on the electron transitions between the Fermi level (EF) and the 3d band, while those of the semiconducting hollow ZnO nanoballoons are ascribed to the near band edge (NBE) and deep level electron transitions. The PL emissions of the metal-semiconductor concentric solid Zn/ZnO nanospheres are attributed to the electron transitions across the metal-semiconductor junction, from the EF to the valence and 3d bands, and from the interface states to the valence band. All three nanostructures are excellent room-temperature light emitters. PMID:25382186

  18. Spontaneous droplet formation techniques for monodisperse emulsions preparation – Perspectives for food applications

    NARCIS (Netherlands)

    Maan, A.A.; Schroën, C.G.P.H.; Boom, R.M.

    2011-01-01

    Spontaneous droplet formation through Laplace pressure differences is a simple method for making monodisperse emulsions and is claimed to be suited for shear and temperature sensitive products, and those requiring high monodispersity. Techniques belonging to this category include (grooved) microchan

  19. E ective Doping of Rare-earth Ionsin Silica Gel:A Novel Approach to Design Active Electronic Devices

    Institute of Scientific and Technical Information of China (English)

    D. Haranath∗; Savvi Mishra; Amish G. Joshi; Sonal Sahai; Virendra Shanker

    2011-01-01

    Eu3+luminescence spectroscopy has been used to investigate the effective doping of alkoxide-based silica (SiO2) gels using a novel pressure-assisted sol-gel method. Our results pertaining to intense photolumi-nescence (PL) from gel nanospheres can be directly attributed to the high specific surface area and remarkable decrease in unsaturated dangling bonds of the gel nanospheres under pressure. An increased dehydroxylation in an autoclave resulted in enhanced red (∼611 nm) PL emission from europium and is almost ten times brighter than the SiO2 gel made at atmospheric pressure and∼50℃ using conventional St¨ober-Fink-Bohn process. The presented results are entirely different from those reported earlier for SiO2:Eu3+ gel nanospheres and the origin of the enhanced PL have been discussed thoroughly.

  20. Facile fabrication of dual emissive nanospheres via the self-assembling of CdSe@CdS and zinc phthalocyanine and their application for silver ion detection

    Science.gov (United States)

    Liu, Shuning; Liu, Chenchen; Luan, Xinying; Yao, Rui; Feng, Yakai

    2017-09-01

    The far-red/near infrared photoluminescence of zinc phthalocyanines would be strongly quenched once they are aggregated, which will obviously hinder their wide applications in environmental, energy related and biomedical fields. Herein, the ultra-small sized semiconductor quantum dots with core-shell structures (CdSe@CdS) have been firstly synthesized and then assembled with a dendritic zinc phthalocyanine (ZnPc) in the H2O/DMF mixed solvent to obtain monodispersed nanospheres. Finally, it was found that the resultant ethanolic colloids can be employed as a sensitive and specific fluorescent nanoprobe for silver ions discrimination with a limit of detection (LOD) approaching to 10-8 mol/L.

  1. Second harmonic generation from an individual amorphous selenium nanosphere

    Science.gov (United States)

    Ma, C. R.; Yan, J. H.; Wei, Y. M.; Yang, G. W.

    2016-10-01

    Among the numerous nonlinear optics effects, second harmonic generation (SHG) is always a hotspot and it is extensively used for optical frequency conversion, biomedical imaging, etc. However, SHG is forbidden in a medium with inversion symmetry under the electric-dipole approximation. Here, we demonstrated SHG from a single amorphous selenium (a-Se) nanosphere under near-infrared femtosecond pulse excitation. It was found that SH spectra are tunable with the size of a-Se nanospheres and the SHG efficiency of a single a-Se sphere with a diameter over 300 nm is estimated at 10-8. We also established two physical mechanisms of SHG from the amorphous nanospheres. There is an electric-dipole contribution to the second-order nonlinearity in view of the inevitable structural discontinuity at the surface. The discontinuity of the normal component of the electric field strength leads to the quadrupole-type contributions arising from the large electric field gradient. The SHG process can be enhanced by resonance near the fundamental wavelength, giving rise to the detectable second harmonic (SH) spectra of a single a-Se nanosphere (d > 300 nm) or two small a-Se nanospheres (d = 200 nm) aggregated into a dimer, while the single nanosphere with smaller size (d > 300 nm) is undetectable. As an essential trace element for animals, a-Se features unique biological compatibility and has specific properties of optical nonlinearity within the optical window in biological tissue. This discovery makes a-Se nanospheres promising both in nonlinear optics and biomedicine.

  2. Thermoplastic polyurethanes with TDI-based monodisperse hard segments

    NARCIS (Netherlands)

    De, D.; Araichimani, A.; ten Hoopen, Hermina W.M.; Gaymans, R.J.

    2009-01-01

    Polyurethanes with PTMO soft segments and toluene diisocyanate diamide as urethane segment were studied. The toluene diisocyanate diamide urethane segment was monodisperse in length. The soft segment length was changed by extending PTMO with TDI units to a soft segment length varying from 2 250 to

  3. Highly monodisperse bismuth nanoparticles and their three-dimensional superlattices.

    Science.gov (United States)

    Yarema, Maksym; Kovalenko, Maksym V; Hesser, Günter; Talapin, Dmitri V; Heiss, Wolfgang

    2010-11-01

    A simple and reproducible synthesis of highly monodisperse and ligand-protected bismuth nanoparticles (Bi NPs) is reported. The size of the single-crystalline and spherically shaped NPs is controlled between 11 and 22 nm mainly by the reaction temperature. The high uniformity of the NPs allows their self-assembly into long-range-ordered two- and three-dimensional superstructures.

  4. Porous TiO2 Assembled from Monodispersed Nanoparticles.

    Science.gov (United States)

    Liu, Xu; Duan, Weijie; Chen, Yan; Jiao, Shihui; Zhao, Yue; Kang, Yutang; Li, Lu; Fang, Zhenxing; Xu, Wei; Pang, Guangsheng

    2016-12-01

    Porous TiO2 were assembled by evaporating or refluxing TiO2 colloid, which was obtained by dispersing the TiO2 nanoparticles with a crystallite size (d XRD) of 3.2 nm into water or ethanol without any additives. Porous transparent bulk TiO2 was obtained by evaporating the TiO2-C2H5OH colloid at room temperature for 2 weeks, while porous TiO2 nanospheres were assembled by refluxing the TiO2-H2O colloid at 80 °C for 36 h. Both of the porous TiO2 architectures were pore-size-adjustable depending on the further treating temperature. Porous TiO2 nanospheres exhibited enhanced photocatalysis activity compared to the nanoparticles.

  5. Preparation and structure characterization of nanospherical MCM- 41 molecular sieves

    Directory of Open Access Journals (Sweden)

    CHEN Ting

    2013-04-01

    Full Text Available Nanospherical MCM-41 molecular sieves have been synthesized by using hexadecyl trimethyl ammonium bromide (CTAB as templates and tetraethyl orthosilicate (TEOS as silicon sources. XRD,SEM,FT-IR,TEM,and N2 adsorption-desorption isotherms were used to investigate the effects of the reaction temperature and aging time on the morphology and structure of the samples. The results show that the nanospherical MCM-41 particles can be obtained at reaction temperatures between 20 to 80℃. With the reaction temperature increasing,the diameter of the nanospheres increases. When the reaction temperature reaches 110℃,MCM-41 molecular sieves exhibit irregular particle morphology. With the aging time of 0-15 h,the dispersion of nanospherical MCM-41 molecular sieves is very good. However,as the aging time increases,the particle size is also increased,while agglomeration is also more serious. Besides,the optimal synthesis conditions of the nanospherical MCM-41 molecular sieves were obtained by analyzing their formation mechanism.

  6. Mechanistic investigation into the spontaneous linear assembly of gold nanospheres

    KAUST Repository

    Yang, Miaoxin

    2010-01-01

    Understanding the mechanism of nanoparticle self-assembly is of critical significance for developing synthetic strategies for complex nanostructures. By encapsulating aggregates of Au nanospheres in shells of polystyrene-block- poly(acrylic acid), we prevent the dissociation and aggregation typically associated with the drying of solution samples on TEM/SEM substrates. In our study of the salt-induced aggregation of 2-naphthalenethiol-functionalized Au nanospheres in DMF, the trapping of the solution species under various experimental conditions permits new insights in the mechanism thereof. We provide evidence that the spontaneous linear aggregation in this system is a kinetically controlled process and hence the long-range charge repulsion at the "transition state" before the actual contact of the Au nanospheres is the key factor. Thus, the charge repulsion potential (i.e. the activation energy) a nanosphere must overcome before attaching to either end of a nanochain is smaller than attaching on its sides, which has been previously established. This factor alone could give rise to the selective end-on attachment and lead to the linear assembly of originally isotropic Au nanospheres. © 2010 the Owner Societies.

  7. Monodisperse Ag@SiO2 core-shell nanoparticles as active inhibitors for marine anticorrosion applications.

    Science.gov (United States)

    Zhang, Xin-Sheng; Wang, Jie-Xin; Xu, Ke; Le, Yuan; Chen, Jian-Feng

    2011-04-01

    Monodisperse Ag@SiO2 core-shell structured nanoparticles were firstly utilized as a novel corrosion inhibitor for marine anticorrosion applications. The related marine anticorrosion properties were evaluated with an electrochemical noise (ECN) analysis during 2 weeks of accelerated immersion tests in natural seawater with the addition of various inorganic salts and nutriments. The experimental results indicate that the corrosion activity is markedly reduced by nearly 1-3 orders of magnitude owing to the introduction of Ag@SiO2 core-shell nanoparticles into coating. The inhibition efficiency of corrosion can reach as high as about 99%. More importantly, such a coating exhibits an excellent long-term sustained marine anticorrosion effect. So it could be reasonably inferred that silver cores as active inhibitors effectively prevent the corrosion damage from microorganisms, while silica shells act as a good protection for silver nanoparticles, delay the release of silver ions, and also function as the corrosion inhibiting action for inorganic salts. Therefore, this would make monodisperse Ag@SiO2 core-shell nanoparticles a potential and promising corrosion inhibitor for developing future advanced multifunctional coatings.

  8. Structural and physicochemical aspects of silica encapsulated ZnO quantum dots with high quantum yield and their natural uptake in HeLa cells.

    Science.gov (United States)

    Depan, D; Misra, R D K

    2014-09-01

    Photoluminescent semiconductor quantum dots (QDs) are of significant interest for bioimaging and fluorescence labeling. In this regard, we describe here the design of high sensitivity and high specificity non-toxic ZnO QDs (∼5 nm) with long-term stability of up to 12 months. The embedding of ZnO QDs on silica nanospheres led to significant increase in photoluminescence intensity rendering them highly bright QD-based probes. The QDs were characterized in vitro with respect to cancer cells (HeLa) and evaluated in terms of viability, fluorescence and cytoskeletal organization. The immobilization of ZnO QDs on silica nanospheres promoted the internalization and enhanced fluorescence emission of HeLa cells. The fluorescence emission from QDs was stable for 3 days, indicating excellent stability toward photobleaching. Cytoskeletal reorganization was observed after internalization of QDs such that the ZnO QDS on silica nanospheres resulted in broadening of the actin cytoskeleton. The study underscores that ZnO QDs immobilized on Si nanospheres are promising for tracking cancer cells in cell therapy.

  9. Enriching PMMA nanospheres with adjustable charges as novel templates for multicolored dye-PMMA nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Wang Xumei; Xu Shuping; Xu Weiqing [State Key Laboratory of Supramolecular Structure and Materials, Jilin University, Changchun 130012 (China); Liang Chongyang; Li Hongrui; Sun Fei, E-mail: xuwq@jlu.edu.cn [Institute of Frontier Medical Science, Jilin University, Changchun 130021 (China)

    2011-07-08

    Multicolored fluorescent dye loaded PMMA nanospheres were synthesized by the electrostatic adsorption of dye molecules on the charged PMMA nanospheres, whose charges were adjusted by choosing different initiators. The charged PMMA nanospheres have a wider capacity and advantage for combining the charged dyes. The fluorescent dye-PMMA composite nanospheres possess the advantages of higher brightness, longer lifetime and stronger resistance to photobleaching relative to dye molecules. Dye leakage remained lower than 5% over one week. These fluorescent nanospheres have been used in biological labels in cell imaging. They can easily stain blood cancer cells without further surface modification.

  10. Synthesis of Silica Nanoparticles by Sol-Gel: Size-Dependent Properties, Surface Modification, and Applications in Silica-Polymer Nanocomposites—A Review

    Directory of Open Access Journals (Sweden)

    Ismail Ab Rahman

    2012-01-01

    Full Text Available Application of silica nanoparticles as fillers in the preparation of nanocomposite of polymers has drawn much attention, due to the increased demand for new materials with improved thermal, mechanical, physical, and chemical properties. Recent developments in the synthesis of monodispersed, narrow-size distribution of nanoparticles by sol-gel method provide significant boost to development of silica-polymer nanocomposites. This paper is written by emphasizing on the synthesis of silica nanoparticles, characterization on size-dependent properties, and surface modification for the preparation of homogeneous nanocomposites, generally by sol-gel technique. The effect of nanosilica on the properties of various types of silica-polymer composites is also summarized.

  11. Multifunctional antireflection coatings based on novel hollow silica-silica nanocomposites.

    Science.gov (United States)

    Zhang, Xianpeng; Lan, Pinjun; Lu, Yuehui; Li, Jia; Xu, Hua; Zhang, Jing; Lee, YoungPak; Rhee, Joo Yull; Choy, Kwang-Leong; Song, Weijie

    2014-02-12

    Antireflection (AR) coatings that exhibit multifunctional characteristics, including high transparency, robust resistance to moisture, high hardness, and antifogging properties, were developed based on hollow silica-silica nanocomposites. These novel nanocomposite coatings with a closed-pore structure, consisting of hollow silica nanospheres (HSNs) infiltrated with an acid-catalyzed silica sol (ACSS), were fabricated using a low-cost sol-gel dip-coating method. The refractive index of the nanocomposite coatings was tailored by controlling the amount of ACSS infiltrated into the HSNs during synthesis. Photovoltaic transmittance (TPV) values of 96.86-97.34% were obtained over a broad range of wavelengths, from 300 to 1200 nm; these values were close to the theoretical limit for a lossy single-layered AR coating (97.72%). The nanocomposite coatings displayed a stable TPV, with degradation values of less than 4% and 0.1% after highly accelerated temperature and humidity stress tests, and abrasion tests, respectively. In addition, the nanocomposite coatings had a hardness of approximately 1.6 GPa, while the porous silica coatings with an open-pore structure showed more severe degradation and had a lower hardness. The void fraction and surface roughness of the nanocomposite coatings could be controlled, which gave rise to near-superhydrophilic and antifogging characteristics. The promising results obtained in this study suggest that the nanocomposite coatings have the potential to be of benefit for the design, fabrication, and development of multifunctional AR coatings with both omnidirectional broadband transmission and long-term durability that are required for demanding outdoor applications in energy harvesting and optical instrumentation in extreme climates or humid conditions.

  12. SYNTHESIS OF CdS/SiO2/POLYMER TRI-LAYER FLUORESCENT NANOSPHERES WITH FUNCTIONAL POLYMER SHELLS

    Institute of Scientific and Technical Information of China (English)

    Bin Liu; Feng-kai Yang; Guang-yu Liu; Xin-lin Yang

    2012-01-01

    Tri-layer CdS/SiO2/polymer hybrid nanospheres were synthesized by distillation precipitation polymerization of either ethyleneglycol dimethacrylate (EGDMA) or EGDMA together with comonomers having different functional groups,such as methacrylic acid,4-vinylpyridine and 2-hydroxyethylmethacrylate,in the presence of 3-(methacryloxy)propyl trimethoxysilane (MPS)-modified CdS/SiO2 nanoparticles as seeds in acetonitrile with 2,2'-azobisisobutyronitrile (AIBN) as initiator.In this approach,MPS-modified inorganic seeds were prepared by the modification of CdS/SiO2 nanoparticles via the self-condensation reaction between the hydroxyl groups of sinaols,in which the CdS/SiO2 nanoparticles were afforded by a reverse microemulsion technique for the synthesis of CdS core nanoparticles with the subsequent coating of silica layer.The polymer shell-layers encapsulated over the MPS-modified CdS/SiO2 inorganic seeds via the efficient capture of the monomers and oligomers from the solution with the aid of the vinyl groups incorporated by the MPS modification,in which the polymer shell-thickness and functional groups including carboxyl,pyridyl and hydroxyl,were facilely controlled by the feed of EGDMA as well as the types of comonomers used for the polymerization.These nanospheres were characterized by transmission electron microscopy (TEM),Fourier-transform infrared spectroscopy (FT-IR),thermogravimetric analysis (TGA),fluorescence spectroscopy and zeta potential.

  13. Antimicrobial nanospheres thin coatings prepared by advanced pulsed laser technique

    OpenAIRE

    Alina Maria Holban; Valentina Grumezescu; Alexandru Mihai Grumezescu; Bogdan Ştefan Vasile; Roxana Truşcă; Rodica Cristescu; Gabriel Socol; Florin Iordache

    2014-01-01

    We report on the fabrication of thin coatings based on polylactic acid-chitosan-magnetite-eugenol (PLA-CS-Fe3O4@EUG) nanospheres by matrix assisted pulsed laser evaporation (MAPLE). Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) investigation proved that the homogenous Fe3O4@EUG nanoparticles have an average diameter of about 7 nm, while the PLA-CS-Fe3O4@EUG nanospheres diameter sizes range between 20 and 80 nm. These MAPLE-deposited coatings acted as bioactive ...

  14. A co-flow-focusing monodisperse microbubble generator

    KAUST Repository

    Zhang, Jiaming

    2014-02-14

    We use a simple and inexpensive microfluidic device, which is based on microscope glass slides and two tapered glass capillaries, to produce monodisperse microbubbles. The innermost capillary used for transporting the gas is inserted into the second capillary, with its 2 μm sharp tip aligned with the center of the converging-diverging throat of the second capillary. This configuration provides a small and smooth gas flow rate, and a high velocity gradient at the tube outlet. Highly monodisperse microbubbles with diameters ranging from 3.5 to 60 microns have been successfully produced at a rate of up to 40 kHz. A simple scaling law, which is based on the capillary number and liquid-to-gas flow rate ratio, successfully predicts the bubble size. © 2014 IOP Publishing Ltd.

  15. Synthesis and antimicrobial activity of monodisperse copper nanoparticles.

    Science.gov (United States)

    Kruk, Tomasz; Szczepanowicz, Krzysztof; Stefańska, Joanna; Socha, Robert P; Warszyński, Piotr

    2015-04-01

    Metallic monodisperse copper nanoparticles at a relatively high concentration (300 ppm CuNPs) have been synthesized by the reduction of copper salt with hydrazine in the aqueous SDS solution. The average particles size and the distribution size were characterized by Dynamic Light Scattering (DLS), Nanosight-Nanoparticle Tracking Analysis (NTA). The morphology and structure of nanoparticles were investigated using Scanning Electron Microscopy (SEM). The chemical composition of the copper nanoparticles was determined by X-ray Photoelectron Spectroscopy (XPS). Monodisperse copper nanoparticles with average diameter 50 nm were received. UV/vis absorption spectra confirmed the formation of the nanoparticles with the characteristic peak 550 nm. The antimicrobial studies showed that the copper nanoparticles had high activity against Gram-positive bacteria, standard and clinical strains, including methicillin-resistant Staphylococcus aureus, comparable to silver nanoparticles and some antibiotics. They also exhibited antifungal activity against Candida species. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Synthesis of Monodisperse Iron Oxide Nanoparticles without Surfactants

    Directory of Open Access Journals (Sweden)

    Xiao-Chen Yang

    2014-01-01

    Full Text Available Monodisperse iron oxide nanoparticles could be successfully synthesized with two kinds of precipitants through a precipitation method. As-prepared nanoparticles in the size around 10 nm with regular spherical-like shape were achieved by adjusting pH values. NaOH and NH3·H2O were used as two precipitants for comparison. The average size of nanoparticles with NH3·H2O precipitant got smaller and represented better dispersibility, while nanoparticles with NaOH precipitant represented better magnetic property. This work provided a simple method without using any organic solvents, organic metal salts, or surfactants which could easily obtain monodisperse nanoparticles with tunable morphology.

  17. Preparation and Characterization of Monodisperse Nickel Nanoparticles by Polyol Process

    Institute of Scientific and Technical Information of China (English)

    LI Peng; GUAN Jianguo; ZHANG Qingjie; ZHAO Wenyu

    2005-01-01

    Polymer-protected monodisperse nickel nanoparticles were synthesized by a modified polyol reduction method in the presence of poly ( N-vinyl- 2-pyrrolidone ). These nanoparticles were characterized by transmission electron microscopy (TEM), X- ray diffraction ( XRD ), selected area electron diffraction ( SAED ), as well as vibrating sample magnetometer (VSM). The experimental results show that the addition of PVP and the concentration of NaOH have strong influences on the size, agglomeration and uniformity of nanoparticles. In the presence of PVP and NaOH with low concentrations, monodisperse nickel nanoparticles with average diameters about 42 nm were obtained and characterized to be pure nickel crystalline with fcc structure. Secondary structures such as clusters, loops, and strings resulted from magnetic interactions between particles were observed. The chemical interaction between the PVP and nickel nanoparticles was found by FTIR. The saturation magnetization ( Ms ), remanent magnetization (Mr) and coercivity ( Hc ) of these nickel nanoparticles are lower than those of bulk nickel.

  18. Monodispersive CoPt Nanoparticles Synthesized Using Chemical Reduction Method

    Institute of Scientific and Technical Information of China (English)

    SHEN Cheng-Min; HUI Chao; YANG Tian-Zhong; XIAO Cong-Wen; CHEN Shu-Tang; DING Hao; GAO Hong-Jun

    2008-01-01

    @@ Monodispersive CoPt nanoparticles in sizes of about 2.2 nm are synthesized by superhydride reduction of CoCl2 and PtCl2 in diphenyl ether. The as-prepared nanoparticles show a chemically disordered A1 structure and are superparamagnetic. Thermal annealing transforms the A1 structure into chemically ordered L1o structure and the particles are ferromagnetic at room temperature.

  19. Monodisperse magnesium hydride nanoparticles uniformly self-assembled on graphene.

    Science.gov (United States)

    Xia, Guanglin; Tan, Yingbin; Chen, Xiaowei; Sun, Dalin; Guo, Zaiping; Liu, Huakun; Ouyang, Liuzhang; Zhu, Min; Yu, Xuebin

    2015-10-21

    Monodisperse MgH2 nanoparticles with homogeneous distribution and a high loading percent are developed through hydrogenation-induced self-assembly under the structure-directing role of graphene. Graphene acts not only as a structural support, but also as a space barrier to prevent the growth of MgH2 nanoparticles and as a thermally conductive pathway, leading to outstanding performance.

  20. Three-dimensional Ordered Silica Colloidal Film Self-assembly Deposited on a Vertical Substrate

    Institute of Scientific and Technical Information of China (English)

    刘丽霞; 董鹏; 王晓冬; 程丙英

    2003-01-01

    A method for preparation of particle crystal film constructed trom monodisperse silica colloidal partices in diameter of about 300 nm is reported. The films were prepared from an ethanol suspension by vertical deposition that relies on capillary forces to assemble colloidal crystal particles on a vertical substrate. The 3D ordered films were characterized by transmission spectra and scanning electric microscope (SEM). The effect of evaporation temperature, particle concentration and sintered temperature on the quality of colloidal particle crystal film was investigated.

  1. Facile Synthesis of Monodisperse CdS Nanocrystals via Microreaction

    Directory of Open Access Journals (Sweden)

    Zhou Xinggui

    2009-01-01

    Full Text Available Abstract CdS-based nanocrystals (NCs have attracted extensive interest due to their potential application as key luminescent materials for blue and white LEDs. In this research, the continuous synthesis of monodisperse CdS NCs was demonstrated utilizing a capillary microreactor. The enhanced heat and mass transfer in the microreactor was useful to reduce the reaction temperature and residence time to synthesize monodisperse CdS NCs. The superior stability of the microreactor and its continuous operation allowed the investigation of synthesis parameters with high efficiency. Reaction temperature was found to be a key parameter for balancing the reactivity of CdS precursors, while residence time was shown to be an important factor that governs the size and size distribution of the CdS NCs. Furthermore, variation of OA concentration was demonstrated to be a facile tuning mechanism for controlling the size of the CdS NCs. The variation of the volume percentage of OA from 10.5 to 51.2% and the variation of the residence time from 17 to 136 s facilitated the synthesis of monodisperse CdS NCs in the size range of 3.0–5.4 nm, and the NCs produced photoluminescent emissions in the range of 391–463 nm.

  2. Metal Fe{sup 3+} ions assisted synthesis of highly monodisperse Ag/SiO{sub 2} nanohybrids and their antibacterial activity

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Nianchun; Xue, Feng [College of Material Science and Engineering, South China University of Technology, Guangzhou 510641 (China); Yu, Xiang [Analytical and Testing Center, Jinan University, Guangzhou 510632 (China); Zhou, Huihua [Guangdong East Sunshine Pharmaceutical Co., Ltd., Dongguan 523871 (China); Ding, Enyong, E-mail: eyding@scut.edu.cn [College of Material Science and Engineering, South China University of Technology, Guangzhou 510641 (China)

    2013-02-15

    Graphical abstract: TEM images of the Ag/SiO{sub 2}-2 nanohybrids. The homogeneous and more mono-disperse Ag nanoparticles deposit on SiO{sub 2} spheres. Through this method, Ag nanoparticles are easily formed on the surface of SiO{sub 2} compared to other methods. Highlights: Black-Right-Pointing-Pointer We prepared homogeneous and mono-dispersed Ag/SiO{sub 2}-2 nanohybrids by adding Fe{sup 3+} ions. Black-Right-Pointing-Pointer The Ag/SiO{sub 2}-2 nanohybrids had core(SiO{sub 2})-shell(Ag) structure. Black-Right-Pointing-Pointer The Ag/SiO{sub 2}-2 nanohybrids exhibited excellent antibacterial activity against bacteria. Black-Right-Pointing-Pointer The reaction temperature was lower and the yield of Ag/SiO{sub 2}-2 nanohybrids were higher. - Abstract: Highly monodispersed Ag/SiO{sub 2} nanohybrids with excellent antibacterial property were synthesized by using DMF as a reducing agent and employing an additional redox potential of metal Fe{sup 3+} ion as a catalytic agent. The obtained Ag/SiO{sub 2}-2 nanohybrids of about 240 nm were highly monodispersity and uniformity by adding trace Fe{sup 3+} ions into the reaction which Ag{sup +} reacted with N,N-dimethyl formamide (DMF) at 70 Degree-Sign C. Compared to the conventional techniques, which need long time and high temperature for silica coating of Ag nanoparticles, this new method was capable of synthesizing monodispersed, uniform, high yield Ag/SiO{sub 2} nanohybrids. The electron was transferred from the Fe{sup 2+} ion to the Ag{sup +} ion to accelerate the nucleation of silver nanoparticles. The chemical structures, morphologies and properties of the Ag/SiO{sub 2} nanohybrids were characterized by X-ray diffraction (XRD), (High-resolution, Scanning transmission) transmission electron microscopy (TEM, HRTEM and STEM), and X-ray photoelectron spectroscopy (XPS), and UV-vis spectroscopy (UV-vis) and test of antibacterial. The results demonstrated that the silver nanoparticles supported on the surface of Si

  3. Synthesis and characterization of magnetically recyclable Ag nanoparticles immobilized on Fe3O4@C nanospheres with catalytic activity

    Science.gov (United States)

    Li, Wei-hong; Yue, Xiu-ping; Guo, Chang-sheng; Lv, Jia-pei; Liu, Si-si; Zhang, Yuan; Xu, Jian

    2015-04-01

    A novel approach for the synthesis of Ag-loaded Fe3O4@C nanospheres (Ag-Fe3O4@C) was successfully developed. The catalysts possessed a carbon-coated magnetic core and grew active silver nanoparticles on the outer shell using hydrazine monohydrate as the AgNO3 reductant in ethanol. The morphology, inner structure, and magnetic properties of the as-prepared composites were studied with transmission electron microscopy (TEM), X-ray powder diffraction (XRD), fourier translation infrared spectroscopy (FT-IR), and vibrating sample magnetometer (VSM) techniques. Catalytic activity was investigated by degrading rhodamine B (RhB) in the designed experiment. The obtained products were monodispersed and bifunctional with high magnetization, as well as exhibited excellent catalytic activity toward organic dye with 98% of RhB conversion within 20 min in the presence of NaBH4. The product also exhibited convenient magnetic separability and maintained high catalytic activity after six cycle runs.

  4. Hollow Nanospheres Array Fabrication via Nano-Conglutination Technology.

    Science.gov (United States)

    Zhang, Man; Deng, Qiling; Xia, Liangping; Shi, Lifang; Cao, Axiu; Pang, Hui; Hu, Song

    2015-09-01

    Hollow nanospheres array is a special nanostructure with great applications in photonics, electronics and biochemistry. The nanofabrication technique with high resolution is crucial to nanosciences and nano-technology. This paper presents a novel nonconventional nano-conglutination technology combining polystyrenes spheres (PSs) self-assembly, conglutination and a lift-off process to fabricate the hollow nanospheres array with nanoholes. A self-assembly monolayer of PSs was stuck off from the quartz wafer by the thiol-ene adhesive material, and then the PSs was removed via a lift-off process and the hollow nanospheres embedded into the thiol-ene substrate was obtained. Thiolene polymer is a UV-curable material via "click chemistry" reaction at ambient conditions without the oxygen inhibition, which has excellent chemical and physical properties to be attractive as the adhesive material in nano-conglutination technology. Using the technique, a hollow nanospheres array with the nanoholes at the diameter of 200 nm embedded into the rigid thiol-ene substrate was fabricated, which has great potential to serve as a reaction container, catalyst and surface enhanced Raman scattering substrate.

  5. Preparation, Modification, and Application of Hollow Gold Nanospheres

    OpenAIRE

    Qiong-Qiong Ren; Ling-Yu Bai; Xiao-Shuai Zhang; Zhi-Ya Ma; Bo Liu; Yuan-Di Zhao; Yuan-Cheng Cao

    2015-01-01

    Hollow gold nanospheres (HGNs) have great potential applications in biological sensing, biomedical imaging, photothermal therapy, and drug delivery due to their unique localized surface plasmon resonance (LSPR) feature, easy modification, good biocompatibility, and excellent photothermal conversion properties. In this review, the latest developments of HGNs in biosensing, bioimaging, photothermal therapy, and drug delivery are summarized, the synthesis methods, surface modification and biocon...

  6. Shape-induced separation of nanospheres and aligned nanorods

    NARCIS (Netherlands)

    Ahmad, I.; Zandvliet, H.J.W.; Kooij, E.S.

    2014-01-01

    We studied the phase separation and spatial arrangement of gold nanorods and nanospheres after evaporative self-assembly from aqueous suspension. Depending on the position relative to the contact line of the drying droplet, spheres and rods separate into various liquid-crystalline phases. Nanorods e

  7. Silica photonic crystals with quasi-full band gap in the visible region prepared in ethanol

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hui; WANG Xidong; ZHAO Xiaofeng; LI Wenchao; TANG Qing

    2003-01-01

    Monodisperse silica spheres of 252 nm with a standard deviation of 5.7% are prepared by Stber method. By comparison of both of media, ethanol instead of water is used to assemble opal, and the artificial opal has been prepared by the sedimentation in ethanol of silica spheres. The structure of the opal prepared has been examined and discussed. The results show that the artificial opal has a structure similar to the face-centered cubic (fcc) type packed system with silica spheres. Transmission measurements of the artificial opal have been conducted, which shows that the artificial opal is quasi-full band gap silica photonic crystals in the visible region.

  8. Pore fabrication in various silica-based nanoparticles by controlled etching

    KAUST Repository

    Zhao, L. J.

    2010-07-20

    A novel method based on controlled etching was developed to fabricate nanopores on preformed silica nanoparticles (<100 nm in diameter). The obtained monodisperse nanoporous particles could form highly stable homogeneous colloidal solution. Fluorescent silica nanoparticles and magnetic silica-coated γ-Fe 2O 3 nanoparticles were investigated as examples to illustrate that this strategy could be generally applied to various silica-based functional nanoparticles. The results indicated that this method was effective for generating pores on these nanoparticles without altering their original functionalities. The obtained multifunctional nanoparticles would be useful for many biological and biomedical applications. These porous nanoparticles could also serve as building blocks to fabricate three-dimensionally periodic structures that have the potential to be used as photonic crystals. © 2010 American Chemical Society.

  9. Effect of catalyst concentration on size, morphology and optical properties of silica nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Arora, Ekta; Ritu,; Kumar, Sacheen, E-mail: sacheen3@gmail.com [Department of Electronics science, Kurukshetra University, Kurukshetra, Haryana, India-136119 (India); Kumar, Dinesh

    2016-05-06

    Today, nanomaterials play a key role in various fields such as electronics, aerospace, pharmaceuticals and biomedical because of their unique physical, chemical and biological properties which are different from bulk materials. Nano sized silica particles have gained the prominent position in scientific research and have wide applications. The sol-gel method is the best method to synthesize silica nanoparticles because of its potential to produce monodispersed with narrow size distribution at mild conditions. The silica nanoparticles were obtained by hydrolysis of tetraethyl orthosilicate (TEOS) in ethanol act as solvent. The synthesized nanoparticles were characterized by Field Emission Scanning electron Microscope (FE-SEM), UV Spectrometer. The smallest size of silica particles is around 150nm examined by using FE-SEM. The optical properties and band structure was analyzed using UV-visible spectroscopy which is found to be increase by reducing the size of particles. Concentration effect of catalyst on the size, morphology and optical properties were analyzed.

  10. Effect of catalyst concentration on size, morphology and optical properties of silica nanoparticles

    Science.gov (United States)

    Arora, Ekta; Ritu, Kumar, Sacheen; Kumar, Dinesh

    2016-05-01

    Today, nanomaterials play a key role in various fields such as electronics, aerospace, pharmaceuticals and biomedical because of their unique physical, chemical and biological properties which are different from bulk materials. Nano sized silica particles have gained the prominent position in scientific research and have wide applications. The sol-gel method is the best method to synthesize silica nanoparticles because of its potential to produce monodispersed with narrow size distribution at mild conditions. The silica nanoparticles were obtained by hydrolysis of tetraethyl orthosilicate (TEOS) in ethanol act as solvent. The synthesized nanoparticles were characterized by Field Emission Scanning electron Microscope (FE-SEM), UV Spectrometer. The smallest size of silica particles is around 150nm examined by using FE-SEM. The optical properties and band structure was analyzed using UV-visible spectroscopy which is found to be increase by reducing the size of particles. Concentration effect of catalyst on the size, morphology and optical properties were analyzed.

  11. WE-G-BRE-08: Radiosensitization by Olaparib Eluting Nanospheres

    Energy Technology Data Exchange (ETDEWEB)

    Tangutoori, S; Kumar, R; Sridhar, S [Northeastern University, Boston, MA (United States); Korideck, H; Makrigiorgos, G [Dana-Farber Cancer Institute, Boston, MA (United States); Cormack, R [Harvard Medical School, Boston, MA (United States)

    2014-06-15

    Purpose: Permanent prostate brachytherapy often uses inert bio-absorbable spacers to achieve the desired geometric distribution of sources within the prostate. Transforming these spacers into implantable nanoplatforms for chemo-radiation therapy (INCeRT) provides a means of providing sustained in-situ release of radiosensitizers in the prostate to enhance the therapeutic ratio of the procedure. Olaparib, a PARP inhibitor, suppresses DNA repair processes present during low dose rate continuous irradiation. This work investigates the radiosensitizing/DNA damage repair inhibition by NanoOlaparib eluting nanospheres. Methods: Human cell line PC3 (from ATCC), was maintained in F12-k medium supplemented with fetal bovine serum. Clonogenic assay kit (from Fischer Scientific) was used to fix and stain the cells to determine the long term effects of irradiation. Nanoparticle size and zeta potential of nanospheres were determined using a Zeta particle size analyzer. The incorporation of Olaparib in nanospheres was evaluated by HPLC. Irradiation was performed in a small animal irradiator operating at 220 KeV.The long term effects of radio-sensitization with olaparib and nanoolaparib was determined using the clonogenic assay at 2 Gy and 4 Gy doses. The cells were allowed to grow for around 10 doubling cycles, The colonies were fixed and stained using clonogenic assay kit. The excess stain was washed off using DI water and the images were taken using a digital camera. Results: Radiosensitization studies were carried out in prostate cancer cell line, PC3 radiation at 0, 2 and 4Gy doses. Strongest dose response was observed with nanoolaparib treated cells compared to untreated cells. Conclusion: A two stage drug release of drug eluting nanospheres from a biodegradable spacer has been suggested for sustained in-situ release of Olaparib to suppress DNA repair processes during prostate brachytherapy. The Olaparib eluting nanospheres had the same in-vitro radiosensitizing effect as

  12. Silica in Protoplanetary Disks

    CERN Document Server

    Sargent, B A; Tayrien, C; McClure, M K; Li, A; Basu, A R; Manoj, P; Watson, D M; Bohac, C J; Furlan, E; Kim, K H; Green, J D; Sloan, G C

    2008-01-01

    Mid-infrared spectra of a few T Tauri stars (TTS) taken with the Infrared Spectrograph (IRS) on board the Spitzer Space Telescope show prominent narrow emission features indicating silica (crystalline silicon dioxide). Silica is not a major constituent of the interstellar medium; therefore, any silica present in the circumstellar protoplanetary disks of TTS must be largely the result of processing of primitive dust material in the disks surrouding these stars. We model the silica emission features in our spectra using the opacities of various polymorphs of silica and their amorphous versions computed from earth-based laboratory measurements. This modeling indicates that the two polymorphs of silica, tridymite and cristobalite, which form at successively higher temperatures and low pressures, are the dominant forms of silica in the TTS of our sample. These high temperature, low pressure polymorphs of silica present in protoplanetary disks are consistent with a grain composed mostly of tridymite named Ada found...

  13. Multifunctional mesoporous silica catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Victor Shang-Yi; Tsai, Chih-Hsiang; Chen, Hung-Ting; Pruski, Marek; Kobayashi, Takeshi

    2015-03-31

    The present invention provides bifunctional silica mesoporous materials, including mesoporous silica nanoparticles ("MSN"), having pores modified with diarylammonium triflate and perfluoroaryl moieties, that are useful for the acid-catalyzed esterification of organic acids with organic alcohols.

  14. Stability studies of colloidal silica dispersions in binary solvent mixtures

    CERN Document Server

    Bean, K H

    1997-01-01

    A series of monodispersed colloidal silica dispersions, of varying radii, has been prepared. These particles are hydrophilic in nature due to the presence of surface silanol groups. Some of the particles have been rendered hydrophobic by terminally grafting n-alkyl (C sub 1 sub 8) chains to the surface. The stability of dispersions of these various particles has been studied in binary mixtures of liquids, namely (i) ethanol and cyclohexane, and (ii) benzene and n-heptane. The ethanol - cyclohexane systems have been studied using a variety of techniques. Adsorption excess isotherms have been established and electrophoretic mobility measurements have been made. The predicted stability of the dispersions from D.V.L.O. calculations is compared to the observed stability. The hydrophilic silica particles behave as predicted by the calculations, with the zeta potential decreasing and the van der Waals attraction increasing with increasing cyclohexane concentration. The hydrophobic particles behave differently than e...

  15. Silica extraction from geothermal water

    Science.gov (United States)

    Bourcier, William L; Bruton, Carol J

    2014-09-23

    A method of producing silica from geothermal fluid containing low concentration of the silica of less than 275 ppm includes the steps of treating the geothermal fluid containing the silica by reverse osmosis treatment thereby producing a concentrated fluid containing the silica, seasoning the concentrated fluid thereby producing a slurry having precipitated colloids containing the silica, and separating the silica from the slurry.

  16. Morphologically and size uniform monodisperse particles and their shape-directed self-assembly

    Science.gov (United States)

    Collins, Joshua E.; Bell, Howard Y.; Ye, Xingchen; Murray, Christopher Bruce

    2015-11-17

    Monodisperse particles having: a single pure crystalline phase of a rare earth-containing lattice, a uniform three-dimensional size, and a uniform polyhedral morphology are disclosed. Due to their uniform size and shape, the monodisperse particles self assemble into superlattices. The particles may be luminescent particles such as down-converting phosphor particles and up-converting phosphors. The monodisperse particles of the invention have a rare earth-containing lattice which in one embodiment may be an yttrium-containing lattice or in another may be a lanthanide-containing lattice. The monodisperse particles may have different optical properties based on their composition, their size, and/or their morphology (or shape). Also disclosed is a combination of at least two types of monodisperse particles, where each type is a plurality of monodisperse particles having a single pure crystalline phase of a rare earth-containing lattice, a uniform three-dimensional size, and a uniform polyhedral morphology; and where the types of monodisperse particles differ from one another by composition, by size, or by morphology. In a preferred embodiment, the types of monodisperse particles have the same composition but different morphologies. Methods of making and methods of using the monodisperse particles are disclosed.

  17. Morphologically and size uniform monodisperse particles and their shape-directed self-assembly

    Energy Technology Data Exchange (ETDEWEB)

    Collins, Joshua E.; Bell, Howard Y.; Ye, Xingchen; Murray, Christopher Bruce

    2017-09-12

    Monodisperse particles having: a single pure crystalline phase of a rare earth-containing lattice, a uniform three-dimensional size, and a uniform polyhedral morphology are disclosed. Due to their uniform size and shape, the monodisperse particles self assemble into superlattices. The particles may be luminescent particles such as down-converting phosphor particles and up-converting phosphors. The monodisperse particles of the invention have a rare earth-containing lattice which in one embodiment may be an yttrium-containing lattice or in another may be a lanthanide-containing lattice. The monodisperse particles may have different optical properties based on their composition, their size, and/or their morphology (or shape). Also disclosed is a combination of at least two types of monodisperse particles, where each type is a plurality of monodisperse particles having a single pure crystalline phase of a rare earth-containing lattice, a uniform three-dimensional size, and a uniform polyhedral morphology; and where the types of monodisperse particles differ from one another by composition, by size, or by morphology. In a preferred embodiment, the types of monodisperse particles have the same composition but different morphologies. Methods of making and methods of using the monodisperse particles are disclosed.

  18. Encapsulated in silica: genome, proteome and physiology of the thermophilic bacterium Anoxybacillus flavithermus

    Energy Technology Data Exchange (ETDEWEB)

    Saw, Jimmy H [Los Alamos National Laboratory; Mountain, Bruce W [NEW ZEALAND; Feng, Lu [NANKAI UNIV; Omelchenko, Marina V [NCBI/NLM/NIH; Hou, Shaobin [UNIV OF HAWAII; Saito, Jennifer A [UNIV OF HAWAII; Stott, Matthew B [NEW ZEALAND; Li, Dan [NANKAI UNIV; Zhao, Guang [NANKAI UNIV; Wu, Junli [NANKAI UNIV; Galperin, Michael Y [NCBI/NLM/NIH; Koonin, Eugene V [NCBI/NLM/NIH; Makarova, Kira S [NCBI/NLM/NIH; Wolf, Yuri I [NCBI/NLM/NIH; Rigden, Daniel J [UNIV OF LIVERPOOL; Dunfield, Peter F [UNIV OF CALGARY; Wang, Lei [NANKAI UNIV; Alam, Maqsudul [UNIV OF HAWAII

    2008-01-01

    Gram-positive bacteria of the genus Anoxybacillus have been found in diverse thermophilic habitats, such as geothermal hot springs and manure, and in processed foods such as gelatin and milk powder. Anoxybacillus flavithermus is a facultatively anaerobic bacterium found in super-saturated silica solutions and in opaline silica sinter. The ability of A. flavithermus to grow in super-saturated silica solutions makes it an ideal subject to study the processes of sinter formation, which might be similar to the biomineralization processes that occurred at the dawn of life. We report here the complete genome sequence of A. flavithermus strain WK1, isolated from the waste water drain at the Wairakei geothermal power station in New Zealand. It consists of a single chromosome of 2,846,746 base pairs and is predicted to encode 2,863 proteins. In silico genome analysis identified several enzymes that could be involved in silica adaptation and biofilm formation, and their predicted functions were experimentally validated in vitro. Proteomic analysis confirmed the regulation of biofilm-related proteins and crucial enzymes for the synthesis of long-chain polyamines as constituents of silica nanospheres. Microbial fossils preserved in silica and silica sinters are excellent objects for studying ancient life, a new paleobiological frontier. An integrated analysis of the A. flavithermus genome and proteome provides the first glimpse of metabolic adaptation during silicification and sinter formation. Comparative genome analysis suggests an extensive gene loss in the Anoxybacillus/Geobacillus branch after its divergence from other bacilli.

  19. A comparative study of non-covalent encapsulation methods for organic dyes into silica nanoparticles

    Directory of Open Access Journals (Sweden)

    Auger Aurélien

    2011-01-01

    Full Text Available Abstract Numerous luminophores may be encapsulated into silica nanoparticles (< 100 nm using the reverse microemulsion process. Nevertheless, the behaviour and effect of such luminescent molecules appear to have been much less studied and may possibly prevent the encapsulation process from occurring. Such nanospheres represent attractive nanoplatforms for the development of biotargeted biocompatible luminescent tracers. Physical and chemical properties of the encapsulated molecules may be affected by the nanomatrix. This study examines the synthesis of different types of dispersed silica nanoparticles, the ability of the selected luminophores towards incorporation into the silica matrix of those nanoobjects as well as the photophysical properties of the produced dye-doped silica nanoparticles. The nanoparticles present mean diameters between 40 and 60 nm as shown by TEM analysis. Mainly, the photophysical characteristics of the dyes are retained upon their encapsulation into the silica matrix, leading to fluorescent silica nanoparticles. This feature article surveys recent research progress on the fabrication strategies of these dye-doped silica nanoparticles.

  20. Nanochannel Arrays for Molecular Sieving and Electrochemical Analysis by Nanosphere Lithography Templated Graphoepitaxy of Block Copolymers.

    Science.gov (United States)

    Fu, Kaiyu; Bohn, Paul W

    2017-07-26

    The ability to design, fabricate, and manipulate materials at the nanoscale is fundamental to the quest to develop technologies to assemble nanometer-scale pieces into larger-scale components and materials, thereby transferring unique nanometer-scale properties to macroscopic objects. In this work, we describe a new approach to the fabrication of highly ordered, ultrahigh density nanochannel arrays that employs nanosphere lithography to template the graphoepitaxy of polystyrene-polydimethylsiloxane, diblock copolymers. By optimizing the well-controlled solvent vapor annealing, overcoating conditions, and the subsequent reactive ion etching processes, silica nanochannel (SNC) arrays with areal densities, ρA, approaching 1000 elements μm(-2), are obtained over macroscopic scales. The integrity and functionality of the SNC arrays was tested by using them as permselective ion barriers to nanopore-confined disk electrodes. The nanochannels allow cations to pass to the disk electrode but reject anions, as demonstrated by cyclic voltammetry. This ion gating behavior can be reversed from cation-permselective to anion-permselective by chemically inverting the surface charge from negative to positive. Furthermore, the conformal SNC array structures obtained could easily be lifted, detached, and transferred to another substrate, preserving the hierarchical organization while transferring the nanostructure-derived properties to a different substrate. These results demonstrate how nanoscale behavior can be replicated over macroscale distances, using electrochemical analysis as a model.

  1. SANS study to probe nanoparticle dispersion in nanocomposite membranes of aromatic polyamide and functionalized silica nanoparticles.

    Science.gov (United States)

    Jadav, Ghanshyam L; Aswal, Vinod K; Singh, Puyam S

    2010-11-01

    Silica nanoparticles produced from organically functionalized silicon alkoxide precursors were incorporated into polyamide film to produce a silica-polyamide nanocomposite membrane with enhanced properties. The dispersion of the silica nanoparticles in the nanocomposite membrane was characterized by performing small-angle neutron scattering (SANS) measurements on dilute reactant systems and dilute solution suspensions of the final product. Clear scattering of monodisperse spherical particles of 10-18 A R(g) were observed from dilute solutions of the initial reactant system. These silica nanoparticles initially reacted with diamine monomers of polyamide and subsequently were transformed into polyamide-coated silica nanoparticles; finally nanoparticle aggregates of 27-45 A R(g) were formed. The nanoparticle dispersion of the membrane as the nanosized aggregates is in corroboration with ring- or chain-like assemblies of the nanoparticles dispersed in the bulk polyamide phase as observed by transmission electron microscopy. It is demonstrated that dispersions of silica nanoparticles as the nanosized aggregates in the polyamide phase could be achieved in the nanocomposite membrane with a silica content up to about 2 wt.%. Nanocomposite membranes with higher silica loading approximately 10 wt.% lead to the formation of large aggregates of sizes over 100 A R(g) in addition to the nanosized aggregates.

  2. A Facile Solvothermal Synthesis of Monodisperse Ni Nanoparticles

    Institute of Scientific and Technical Information of China (English)

    YU Peng-fei; CUI Bin; ZHANG Yan; SHI Qi-zhen

    2008-01-01

    A simple solvothermal approach was developed to synthesize uniform spherical monodisperse Ni nanoparticles, which can easily disperse in nonpolar solvents to form homogenous colloidal solution. The as-prepared sample was characterized by XRD, TEM, and FTIR. The results indicate that Ni nanoparticles have the structure of face-centered cube and a narrow distribution with a diameter of (3.5±0.5) nm. The FTIR spectrum reveals that the as a surfactant. The probable formation mechanism of the spherical nanoparticles was also discussed.

  3. Structural disorder versus spin canting in monodisperse maghemite nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Kubickova, S.; Vejpravova, J., E-mail: vejpravo@fzu.cz [Department of Magnetic Nanosystems, Institute of Physics of the ASCR, v.v.i., Na Slovance 2, 182 21 Prague (Czech Republic); Niznansky, D. [Faculty of Science, Department of Inorganic Chemistry, Charles University in Prague, Albertov 2030, 128 40 Prague (Czech Republic); Morales Herrero, M. P. [Instituto de Ciencia de Materiales de Madrid, CSIC, C/Sor Juana Ins de la Cruz 3, Campus de Cantoblanco, 28049 Madrid (Spain); Salas, G. [Instituto de Ciencia de Materiales de Madrid, CSIC, C/Sor Juana Ins de la Cruz 3, Campus de Cantoblanco, 28049 Madrid (Spain); Instituto Madrileno de Estudios Avanzados en Nanociencia, Campus Universitario de Cantoblanco, 28049 Madrid (Spain)

    2014-06-02

    Monodisperse maghemite nanoparticles with diameter ranging from 7 to 20 nm were examined by the In-field Mössbauer Spectroscopy (IFMS) in varying external magnetic field up to 6 T. Surprisingly, the small-sized particles (7 nm) exhibit nearly no spin canting in contrast to the larger particles with lower surface-to-volume ratio. We demonstrate that the observed phenomenon is originated by lower relative crystallinity of the larger particles with different internal structure. Hence, the persistence of the 2nd and 5th absorption lines in the IFMS cannot be unambiguously assigned to the surface spins.

  4. Monodisperse Silver Nanoparticles Synthesized by a Microwave-Assisted Method

    Institute of Scientific and Technical Information of China (English)

    ZHU Shao-Peng; TANG Shao-Chun; MENG Xiang-Kang

    2009-01-01

    Silver nanoparticles with an average size of about 2Onto are synthesized in a colloidal solution with the aid of microwave irradiation. Neither additional reductant nor stabilizer is required in this microwave-assisted method.The color of the colloidal solution is found to be dark green, different from the characteristic yellow of silver colloidal solutions. The silver nanoparticles in the colloidal solution have a narrow size distribution and large yield quantity. UV-visible absorption spectroscopy analysis reveals that the as-synthesized monodisperse silver nanoparticles have exceptional optical properties. Raman spectroscopy measurements demonstrate that these silver nanoparticles exhibit a notable surface-enhanced Raman scattering ability.

  5. MONODISPERSE MICRON-SIZED POLYACRYLAMIDE PARTICLES SYNTHESIZED BY DISPERSION POLYMERIZATION

    Institute of Scientific and Technical Information of China (English)

    Xin Hou; Bo Gao; Zhe-guo Zhang; Kang-de Yao

    2007-01-01

    Monodisperse micron-sized polyacrylamide (PAM) particles with a regular shape have been successfully prepared through dispersion polymerization of the monomer using a rotary reactor. FTIR and NMR spectroscopic results demonstrated the formation of PAM. POM and TEM observations revealed that PAM particles had a regular shape and good dispersity. A thick layer of surfactant (PVP) still existed on PAM particles after multiple centrifugation and ultrasonic re-dispersion in ethanol, which indicates a strong interaction between PVP and PAM. The effects of various polymerization factors on the average size of PAM particles have also been studied.

  6. Spontaneous luminescence of Eu3+ ions in porous Y2O3 nanospheres

    Science.gov (United States)

    Zaitsev, S. V.; Ermolaeva, Yu. V.; Matveevskaya, N. A.; Zver'kova, I. I.; Tolmachev, A. V.

    2017-06-01

    A study of the luminescence of Eu3+ ions in Y2O3 nanospheres indicates a significant influence of the porous structure of nanoparticles on the luminescence of dopant ions. It is shown that filling the nanopores of initially porous Y2O3 nanospheres shortens the decay time of the spontaneous luminescence of doping europium ions. The change in the decay time is associated with the change in the effective refractive index of the porous nanospheres.

  7. Photocatalytic action of cerium molybdate and iron-titanium oxide hollow nanospheres on Escherichia coli

    Energy Technology Data Exchange (ETDEWEB)

    Kartsonakis, I. A., E-mail: ikartsonakis@ims.demokritos.gr; Kontogiani, P.; Pappas, G. S.; Kordas, G. [NCSR ' DEMOKRITOS' , Sol-Gel Laboratory, Institute of Advanced Materials, Physicochemical Processes, Nanotechnology and Microsystems (Greece)

    2013-06-15

    This study is focused on the production of hollow nanospheres that reveal antibacterial action. Cerium molybdate and iron-titanium oxide hollow nanospheres with a diameter of 175 {+-} 15 and 221 {+-} 10 nm, respectively, were synthesized using emulsion polymerization and the sol-gel process. Their morphology characterization was accomplished using scanning electron microscopy. Their antibacterial action was examined on pure culture of Escherichia coli considering the loss of their viability. Both hollow nanospheres presented photocatalytic action after illumination with blue-black light, but those of cerium molybdate also demonstrated photocatalytic action in the dark. Therefore, the produced nanospheres can be used for antibacterial applications.

  8. Photocatalytic hollow TiO2 and ZnO nanospheres prepared by atomic layer deposition.

    Science.gov (United States)

    Justh, Nóra; Bakos, László Péter; Hernádi, Klára; Kiss, Gabriella; Réti, Balázs; Erdélyi, Zoltán; Parditka, Bence; Szilágyi, Imre Miklós

    2017-06-28

    Carbon nanospheres (CNSs) were prepared by hydrothermal synthesis, and coated with TiO2 and ZnO nanofilms by atomic layer deposition. Subsequently, through burning out the carbon core templates hollow metal oxide nanospheres were obtained. The substrates, the carbon-metal oxide composites and the hollow nanospheres were characterized with TG/DTA-MS, FTIR, Raman, XRD, SEM-EDX, TEM-SAED and their photocatalytic activity was also investigated. The results indicate that CNSs are not beneficial for photocatalysis, but the crystalline hollow metal oxide nanospheres have considerable photocatalytic activity.

  9. Photocatalytic action of cerium molybdate and iron-titanium oxide hollow nanospheres on Escherichia coli

    Science.gov (United States)

    Kartsonakis, I. A.; Kontogiani, P.; Pappas, G. S.; Kordas, G.

    2013-06-01

    This study is focused on the production of hollow nanospheres that reveal antibacterial action. Cerium molybdate and iron-titanium oxide hollow nanospheres with a diameter of 175 ± 15 and 221 ± 10 nm, respectively, were synthesized using emulsion polymerization and the sol-gel process. Their morphology characterization was accomplished using scanning electron microscopy. Their antibacterial action was examined on pure culture of Escherichia coli considering the loss of their viability. Both hollow nanospheres presented photocatalytic action after illumination with blue-black light, but those of cerium molybdate also demonstrated photocatalytic action in the dark. Therefore, the produced nanospheres can be used for antibacterial applications.

  10. Cyclodextrin glucanotransferase immobilization onto functionalized magnetic double mesoporous core–shell silica nanospheres

    Directory of Open Access Journals (Sweden)

    Abdelnasser S.S. Ibrahim

    2014-03-01

    Conclusion: The enhancement of CGTase properties upon immobilization suggested that the applied nano-structured carriers and immobilization protocol are promising approach for industrial bioprocess for production of cyclodextrins using immobilized CGTase.

  11. Immobilization of Organophosphorus Acid Anhydrolase Mutant Y212F on Silica Nanospheres

    Science.gov (United States)

    2016-09-01

    Y212F amino acid designations. 2 E. coli cell cultures were grown in Luria broth (Sigma-Aldrich Company; St. Louis, MO) with 100 µg/mL of...Express purification system (GE Healthcare Life Sciences; Uppsala, Sweden ) with a Q-sepharose column (HiPrep Q FF 16/10; GE Healthcare Life Sciences

  12. Computational simulation and preparation of fluorescent magnetic molecularly imprinted silica nanospheres for ciprofloxacin or norfloxacin sensing.

    Science.gov (United States)

    Gao, Bo; He, Xin-Ping; Jiang, Yang; Wei, Jia-Tong; Suo, Hui; Zhao, Chun

    2014-12-01

    A magnetic molecularly imprinted fluorescent sensor for the sensitive and convenient determination of ciprofloxacin or norfloxacin in human urine was synthesized and characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, ultraviolet/visible spectroscopy, and fluorescence spectroscopy. Both cadmium telluride quantum dots and ferroferric oxide nanoparticles are introduced into the polymer for the rapid separation and detection of the target molecules. The synthesized molecularly imprinted polymers were applied to detect ciprofloxacin or its structural analog norfloxacin in human urine with the detection limit 130 ng/mL. A computational study was developed to evaluate the template-monomer geometry and interaction energy in the polymerization mixture to determine the reaction molar ratio of the template and monomer molecules. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. A novel method for preparing monodispersed polystyrene nanoparticles

    Institute of Scientific and Technical Information of China (English)

    LIU Kaiyi; WANG Zhaoqun

    2007-01-01

    A preparation manner for monodispersed polystyrene(PS)nanoparticles polymerized by using a novel addition procedure of a monomer is suggested.In systems containing a smaller amount of surfactant compared with conventional microemulsion polymerization,the polymerization processes consists of three stages:adding dropwise the first part of the monomer for a few minutes at 80℃ and polymerizing for 1 h;adding collectively the residual part of the monomer and polymerizing at the same temperature for another 1 h;and then polymerizing at 85℃ for another 1 h.Based on discussions on the nucleation mechanism of particles in the polymerization system,the influences of monomer weight added dropwise,and amounts of initiator and emulsifier on the size and distribution of PS particles were investigated.PS nanoparticles with smaller diameter such as a number-average diameter of 18.7 nm and better monodispersity were obtained since the dropped styrene amount was suitable under 20wt-% emulsifier amount and 3wt-% initiator amount based on the monomer.

  14. Porous TiO2 Assembled from Monodispersed Nanoparticles

    OpenAIRE

    Liu, Xu; Duan, Weijie; Chen, Yan; Jiao, Shihui; Zhao, Yue; Kang, Yutang; Li, Lu; Fang, Zhenxing; Xu, Wei; Pang, Guangsheng

    2016-01-01

    Porous TiO2 were assembled by evaporating or refluxing TiO2 colloid, which was obtained by dispersing the TiO2 nanoparticles with a crystallite size (d XRD) of 3.2 nm into water or ethanol without any additives. Porous transparent bulk TiO2 was obtained by evaporating the TiO2-C2H5OH colloid at room temperature for 2 weeks, while porous TiO2 nanospheres were assembled by refluxing the TiO2-H2O colloid at 80 °C for 36 h. Both of the porous TiO2 architectures were pore-size-adjustable depending...

  15. Antimicrobial nanospheres thin coatings prepared by advanced pulsed laser technique.

    Science.gov (United States)

    Holban, Alina Maria; Grumezescu, Valentina; Grumezescu, Alexandru Mihai; Vasile, Bogdan Ştefan; Truşcă, Roxana; Cristescu, Rodica; Socol, Gabriel; Iordache, Florin

    2014-01-01

    We report on the fabrication of thin coatings based on polylactic acid-chitosan-magnetite-eugenol (PLA-CS-Fe3O4@EUG) nanospheres by matrix assisted pulsed laser evaporation (MAPLE). Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) investigation proved that the homogenous Fe3O4@EUG nanoparticles have an average diameter of about 7 nm, while the PLA-CS-Fe3O4@EUG nanospheres diameter sizes range between 20 and 80 nm. These MAPLE-deposited coatings acted as bioactive nanosystems and exhibited a great antimicrobial effect by impairing the adherence and biofilm formation of Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. aeruginosa) bacteria strains. Moreover, the obtained nano-coatings showed a good biocompatibility and facilitated the normal development of human endothelial cells. These nanosystems may be used as efficient alternatives in treating and preventing bacterial infections.

  16. Antimicrobial nanospheres thin coatings prepared by advanced pulsed laser technique

    Directory of Open Access Journals (Sweden)

    Alina Maria Holban

    2014-06-01

    Full Text Available We report on the fabrication of thin coatings based on polylactic acid-chitosan-magnetite-eugenol (PLA-CS-Fe3O4@EUG nanospheres by matrix assisted pulsed laser evaporation (MAPLE. Transmission electron microscopy (TEM and scanning electron microscopy (SEM investigation proved that the homogenous Fe3O4@EUG nanoparticles have an average diameter of about 7 nm, while the PLA-CS-Fe3O4@EUG nanospheres diameter sizes range between 20 and 80 nm. These MAPLE-deposited coatings acted as bioactive nanosystems and exhibited a great antimicrobial effect by impairing the adherence and biofilm formation of Staphylococcus aureus (S. aureus and Pseudomonas aeruginosa (P. aeruginosa bacteria strains. Moreover, the obtained nano-coatings showed a good biocompatibility and facilitated the normal development of human endothelial cells. These nanosystems may be used as efficient alternatives in treating and preventing bacterial infections.

  17. Channeling motion of gold nanospheres on a rippled glassed surface

    Science.gov (United States)

    Gnecco, Enrico; Nita, Pawel; Casado, Santiago; Pimentel, Carlos; Mougin, Karine; Caterina Giordano, Maria; Repetto, Diego; Buatier de Mongeot, Francesco

    2014-12-01

    Gold nanospheres have been manipulated by atomic force microscopy on a rippled glass surface produced by ion beam sputtering and coated with an ultrathin (10 nm thick) graphitic layer. This substrate is characterized by irregular wavy grooves running parallel to a preferential direction. Measurements in ambient conditions show that the motion of the nanoparticles is confined to single grooves (‘channels’), along which the particles move till they are trapped by local bottlenecks. At this point, the particles cross the ripple pattern in a series of consecutive jumps and continue their longitudinal motion along a different channel. Moreover, due to the asymmetric shape of the ripple profiles, the jumps occur in the direction of minimum slope, resembling a ratchet mechanism. Our results are discussed, extending a collisional model, which was recently developed for the manipulation of nanospheres on flat surfaces, to the specific geometry of this problem.

  18. Interchain tube pressure effect in extensional flows of oligomer diluted nearly monodisperse polystyrene melts

    DEFF Research Database (Denmark)

    Rasmussen, Henrik K.; Huang, Qian

    2014-01-01

    We have derived a constitutive equation to explain the extensional dynamics of oligomer-diluted monodisperse polymers, if the length of the diluent has at least two Kuhn steps. These polymer systems have a flow dynamics which distinguish from pure monodisperse melts and solutions thereof, if the ...

  19. Monodisperse Femto- to Atto-liter Droplet Formation Using a Nano-Microchannel Interface

    NARCIS (Netherlands)

    Shui, Lingling; Berg, van den Albert; Eijkel, Jan C.T.; Kim, Tae Song; Lee, Yoon-Sik; Chung, Taek-Dong; Jeon, Noo Li; Suh, Kahp-Yang; Choo, Jaebum; Kim, Yong-Kweon

    2009-01-01

    We demonstrate the production of sub-micrometer diameter monodisperse droplets by using a nano-micro channel interface. A perfectly steady nanoscopic liquid filament can be formed by a geometric confinement which eventually gives rise to a stable production of nearly perfectly monodisperse droplets.

  20. Surface properties of poly(ethylene oxide)-based segmented block copolymers with monodisperse hard segments

    NARCIS (Netherlands)

    Husken, D.; Feijen, Jan; Gaymans, R.J.

    2009-01-01

    The surface properties of segmented block copolymers based on poly(ethylene oxide) (PEO) segments and monodisperse crystallizable tetra-amide segments were studied. The monodisperse crystallizable segments (T6T6T) were based on terephthalate (T) and hexamethylenediamine (6). Due to the crystallinity

  1. Preparation, Modification, and Application of Hollow Gold Nanospheres

    Directory of Open Access Journals (Sweden)

    Qiong-Qiong Ren

    2015-01-01

    Full Text Available Hollow gold nanospheres (HGNs have great potential applications in biological sensing, biomedical imaging, photothermal therapy, and drug delivery due to their unique localized surface plasmon resonance (LSPR feature, easy modification, good biocompatibility, and excellent photothermal conversion properties. In this review, the latest developments of HGNs in biosensing, bioimaging, photothermal therapy, and drug delivery are summarized, the synthesis methods, surface modification and bioconjugation of HGNs are also covered in this summary.

  2. Stress development during reaction of metallic nanospheres with gas

    Energy Technology Data Exchange (ETDEWEB)

    Svoboda, J. [Institute of Physics of Materials, Academy of Sciences of the Czech Republic, Zizkova 22, CZ-616 62 Brno (Czech Republic); Fischer, F.D., E-mail: mechanik@unileoben.ac.at [Institute of Mechanics, Montanuniversitaet Leoben, Franz-Josef-Strasse 18, A-8700 Leoben (Austria)

    2011-01-15

    The formation of stoichiometric M{sub p}X{sub q} hollow nanospheres by reaction of metallic M nanospheres with the gaseous X phase must be preceded by the formation of a sufficiently thick M{sub p}X{sub q} nanoshell on the metallic core of phase M. During this stage, high supersaturation of vacancies in the M core and/or hydrostatic stress in the M core, due to the misfit between the core and the nanoshell, are developed and provide favourable conditions for the hollow nucleation. The misfit is caused by the Kirkendall effect. Based on the application of the thermodynamic extremal principle, a kinetic model of M{sub p}X{sub q} nanoshell formation is derived. The kinetics is driven by the change of the chemical energy due to reaction of the M and X components, the interface and surface energies, and the elastic strain energy due to misfit strain of the whole system. The model is used for simulation of the Cu{sub 2}O shell growth kinetics due to oxidation of a Cu nanosphere, and the results of the simulations are discussed.

  3. Hyperspectral Dark Field Optical Microscopy of Single Silver Nanospheres

    Energy Technology Data Exchange (ETDEWEB)

    El-Khoury, Patrick Z.; Joly, Alan G.; Hess, Wayne P.

    2016-04-07

    We record spectrally (400 nm ≤ λ ≤ 675 nm, Δλ < 4.69 nm) and spatially (diffraction-limited, sampled at 85 nm2/pixel) resolved dark field (DF) scattering from single silver nanospheres of 100 nm in diameter. Hyperspectral DF optical microscopy is achieved by coupling a hyperspectral detector to an optical microscope, whereby spectrally resolved diffraction-limited images of hundreds of silver nanoparticles can be recorded in ~30 seconds. We demonstrate how the centers and edges of individual particles can be localized in 2D to within a single pixel (85 nm2), using a statistical method for examining texture based on a co-occurrence matrix. Subsequently, spatial averaging of the spectral response in a 3x3 pixel area around the particle centers affords ample signal-to-noise to resolve the plasmon resonance of a single silver nanosphere. A close inspection of the scattering spectra of 31 different nanospheres reveals that each particle has its unique (i) relative scattering efficiency, and (ii) plasmon resonance maximum and dephasing time. These observations are suggestive of nanometric structural variations over length scales much finer than the spatial resolution attainable using the all-optical technique described herein.

  4. The Kirkendall effect and nanoscience: hollow nanospheres and nanotubes

    Directory of Open Access Journals (Sweden)

    Abdel-Aziz El Mel

    2015-06-01

    Full Text Available Hollow nanostructures are ranked among the top materials for applications in various modern technological areas including energy storage devices, catalyst, optics and sensors. The last years have witnessed increasing interest in the Kirkendall effect as a versatile route to fabricate hollow nanostructures with different shapes, compositions and functionalities. Although the conversion chemistry of nanostructures from solid to hollow has reached a very advanced maturity, there is still much to be discovered and learned on this effect. Here, the recent progress on the use of the Kirkendall effect to synthesize hollow nanospheres and nanotubes is reviewed with a special emphasis on the fundamental mechanisms occurring during such a conversion process. The discussion includes the oxidation of metal nanostructures (i.e., nanospheres and nanowires, which is an important process involving the Kirkendall effect. For nanospheres, the symmetrical and the asymmetrical mechanisms are both reviewed and compared on the basis of recent reports in the literature. For nanotubes, in addition to a summary of the conversion processes, the unusual effects observed in some particular cases (e.g., formation of segmented or bamboo-like nanotubes are summarized and discussed. Finally, we conclude with a summary, where the prospective future direction of this research field is discussed.

  5. The Kirkendall effect and nanoscience: hollow nanospheres and nanotubes.

    Science.gov (United States)

    El Mel, Abdel-Aziz; Nakamura, Ryusuke; Bittencourt, Carla

    2015-01-01

    Hollow nanostructures are ranked among the top materials for applications in various modern technological areas including energy storage devices, catalyst, optics and sensors. The last years have witnessed increasing interest in the Kirkendall effect as a versatile route to fabricate hollow nanostructures with different shapes, compositions and functionalities. Although the conversion chemistry of nanostructures from solid to hollow has reached a very advanced maturity, there is still much to be discovered and learned on this effect. Here, the recent progress on the use of the Kirkendall effect to synthesize hollow nanospheres and nanotubes is reviewed with a special emphasis on the fundamental mechanisms occurring during such a conversion process. The discussion includes the oxidation of metal nanostructures (i.e., nanospheres and nanowires), which is an important process involving the Kirkendall effect. For nanospheres, the symmetrical and the asymmetrical mechanisms are both reviewed and compared on the basis of recent reports in the literature. For nanotubes, in addition to a summary of the conversion processes, the unusual effects observed in some particular cases (e.g., formation of segmented or bamboo-like nanotubes) are summarized and discussed. Finally, we conclude with a summary, where the prospective future direction of this research field is discussed.

  6. Nanosphericals and nanobundles of ZnO: Synthesis and characterization

    Energy Technology Data Exchange (ETDEWEB)

    Salavati-Niasari, Masoud, E-mail: salavati@kashanu.ac.i [Institute of Nano Science and Nano Technology, University of Kashan, Kashan, P.O. Box 87317-51167 (Iran, Islamic Republic of); Department of Inorganic Chemistry, Faculty of Chemistry, University of Kashan, Kashan, P.O. Box 87317-51167 (Iran, Islamic Republic of); Davar, Fatemeh [Institute of Nano Science and Nano Technology, University of Kashan, Kashan, P.O. Box 87317-51167 (Iran, Islamic Republic of); Khansari, Afsaneh [Department of Chemistry, Faculty of Science, University of Guilan, Rasht, P.O. Box 413354-1914 (Iran, Islamic Republic of)

    2011-01-05

    Research highlights: {yields} ZnO nanospherical has been synthesized using inorganic precursor via thermolysis process. {yields} ZnO nanobundle has been synthesized via thermolysis of [Zn(salen)] in the air at 500 {sup o}C for 5 h. - Abstract: ZnO nanosphericals and nanobundles well dispersion have been synthesized using [(N,N'-bis(salicylaldehydo)ethylenediamine)zinc(II)]; [Zn(salen)] as precursor via two methods. Nanosphericals of ZnO has been prepared via thermal decomposition of [Zn(salen)] in the presence of oleylamine at 290 {sup o}C for 90 min. Also nanobundle of ZnO has been synthesized via thermolysis of [Zn(salen)] in the air at 500 {sup o}C for 5 h. The as-synthesized products were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and scanning electronic microscopy (SEM). The room temperature photoluminescence (PL) spectra of both nanostructures are dominated by the green emission attributed to the oxygen vacancy (V{sub O}) related donor-acceptor transition. Presence of several infrared (IR) inactive vibrational modes in the Fourier transform infrared (FT-IR) absorption spectra of the samples indicates a breakdown of translational symmetry in the nanostructures induced by native defects.

  7. Large-scale synthesis of monodisperse SiC nanoparticles with adjustable size, stoichiometric ratio and properties by fluidized bed chemical vapor deposition

    Science.gov (United States)

    Liu, Rongzheng; Liu, Malin; Chang, Jiaxing

    2017-02-01

    A facile fluidized bed chemical vapor deposition method was proposed for the synthesis of monodisperse SiC nanoparticles by using the single precursor of hexamethyldisilane (HMDS). SiC nanoparticles with average particle size from 10 to 200 nm were obtained by controlling the temperature and the gas ratio. An experimental chemical vapor deposition phase diagram of SiC in the HMDS-Ar-H2 system was obtained and three regions of SiC-Si, SiC and SiC-C can be distinguished. The BET surface area and the photoluminescence properties of the SiC nanoparticles can be adjusted by changing the nanoparticle size. For the SiC nanospheres with free carbon, a novel hierarchical structure with 5 8 nm SiC nanoparticles embedded into the graphite matrix was obtained. The advantages of fluidized bed technology for the preparation of SiC nanoparticles were proposed based on the features of homogenous reaction zone, narrow temperature distribution, ultra-short reactant residence time and mass production.

  8. Efficiency Enhancement of InGaN-Based Solar Cells via Stacking Layers of Light-Harvesting Nanospheres

    OpenAIRE

    Amal M. Al-Amri; Po-Han Fu; Kun-Yu Lai; Hsin-Ping Wang; Lain-Jong Li; Jr-Hau He

    2016-01-01

    An effective light-harvesting scheme for InGaN-based multiple quantum well solar cells is demonstrated using stacking layers of polystyrene nanospheres. Light-harvesting efficiencies on the solar cells covered with varied stacks of nanospheres are evaluated through numerical and experimental methods. The numerical simulation reveals that nanospheres with 3 stacking layers exhibit the most improved optical absorption and haze ratio as compared to those obtained by monolayer nanospheres. The ex...

  9. Hollow Sodium Tungsten Bronze (Na0.15WO3) Nanospheres: Preparation, Characterization, and Their Adsorption Properties

    OpenAIRE

    Zuo Guanke; Guo He; Liu Hui; Zhang Jingyan; Hou Jing; Shen Guangxia; Cheng Ping; Guo Shouwu

    2009-01-01

    Abstract We report herein a facile method for the preparation of sodium tungsten bronzes hollow nanospheres using hydrogen gas bubbles as reactant for chemical reduction of tungstate to tungsten and as template for the formation of hollow nanospheres at the same time. The chemical composition and the crystalline state of the as-prepared hollow Na0.15WO3nanospheres were characterized complementarily, and the hollow structure formation mechanism was proposed. The hollow Na0.15WO3nanospheres sho...

  10. New chitosan nanospheres for the delivery of 5-fluorouracil: preparation, characterization and in vitro studies.

    Science.gov (United States)

    Cavalli, Roberta; Leone, Federica; Minelli, Rosalba; Fantozzi, Roberto; Dianzani, Chiara

    2014-01-01

    The aim of this work was to develop new chitosan nanospheres for the delivery of 5-fluorouracil (5-FU). Drug loaded nanospheres were prepared using a technique derived from a combination of coacervation and emulsion droplet coalescence methods. The size and morphology of nanospheres were characterized by laser light scattering and transmission electron microscopy. The 5-FU interaction with chitosan nanospheres was investigated by DSC analysis and FT-IR spectroscopy. The in vitro release was studied by dialysis bag technique. Cytotoxicity of 5-FU loaded chitosan nanospheres was evaluated in vitro on HT29 and PC-3 cell lines. The effects of 5-FU loaded chitosan nanospheres on adhesion of tumor cells to human umbilical vein endothelial cells (HUVEC) were also investigated. 5-FU loaded chitosan nanospheres appeared with a spherical shape, with a mean diameter of about 200 nm and a negative zeta potential of about - 6.0 mV. The successful interaction between drug and chitosan nanosphere matrix was demonstrated by both DSC and FT-IR analyses. The quantitative determination of 5-FU was assayed by UV-Vis analysis. The encapsulation efficiency of 5-FU content was about 70%. A kinetic study of in vitro release demonstrated that the percentages of 5-FU delivered from nanospheres was approx. 10% after 3 hours. The in vitro studies showed that 5-FU loaded nanospheres were effective in reducing tumor cell proliferation in a time- and concentration-dependent manner. 5-FU nanospheres were also able to inhibit both HT29 and PC-3 adhesion to HUVEC after 48 hours of treatment.

  11. Water and oil repellency of flexible silica-coated polymeric substrates

    Science.gov (United States)

    Hsieh, Chien-Te; Cheng, Yu-Shun; Hsu, Shu-Min; Lin, Jia-Yi

    2010-06-01

    A facile coating technique was used for the one-step creation of silica-sphere layers onto flexible polypropylene (PP) substrates, which showed the enhanced repellency toward liquid droplets with different surface tensions, ranging from 25.6 to 72.3 mN/m. One-step solution preparation comprised the homogenous mixing of colloidal silica nanospheres and perfluoroalkyl methacrylic copolymer, and the resulting F-silica slurry was subsequently deposited over the PP films, which showed good adhesion. The flexible silica-coated polymeric film displayed a remarkable repellency toward water and oil drops, when compared with the F-coated PP flat film. The silica-stacking layers on the PP substrate generated a roughened surface, owing to the creation of bionic surface hierarchically combined with multiple-scale architecture. To clarify this, the wetted fraction was determined from Cassie-Baxter equation, and the work of adhesion, based on Young-Duprè equation, was used to examine the sliding ability of the resulting polymeric films. The cross-cut test incorporated with film bending proved the excellent adherence between silica layer and PP substrate. A satisfactory durability in water and oil immersions for 10 days showed that the resulting PP film possesses strong adhesion and better repellency for a long period, confirming a promising commercial feasibility.

  12. SILICA SURFACED CARBON FIBERS.

    Science.gov (United States)

    carbon fibers . Several economical and simple processes were developed for obtaining research quantities of silica surfaced carbon filaments. Vat dipping processes were utilized to deposit an oxide such as silica onto the surface and into the micropores of available carbon or graphite base fibers. High performance composite materials were prepared with the surface treated carbon fibers and various resin matrices. The ablative characteristics of these composites were very promising and exhibited fewer limitations than either silica or...treated

  13. Biomimetic synthesis of selenium nanospheres by bacterial strain JS-11 and its role as a biosensor for nanotoxicity assessment: a novel se-bioassay.

    Directory of Open Access Journals (Sweden)

    Sourabh Dwivedi

    Full Text Available Selenium nanoparticles (Se-NPs were synthesized by green technology using the bacterial isolate Pseudomonas aeruginosa strain JS-11. The bacteria exhibited significant tolerance to selenite (SeO3(2- up to 100 mM concentration with an EC50 value of 140 mM. The spent medium (culture supernatant contains the potential of reducing soluble and colorless SeO3(2- to insoluble red elemental selenium (Se(0 at 37°C. Characterization of red Se° product by use of UV-Vis spectroscopy, X-ray diffraction (XRD, atomic force microscopy (AFM and transmission electron microscopy (TEM with energy dispersive X-ray spectrum (EDX analysis revealed the presence of stable, predominantly monodispersed and spherical selenium nanoparticles (Se-NPs of an average size of 21 nm. Most likely, the metabolite phenazine-1-carboxylic acid (PCA released by strain JS-11 in culture supernatant along with the known redox agents like NADH and NADH dependent reductases are responsible for biomimetic reduction of SeO3(2- to Se° nanospheres. Based on the bioreduction of a colorless solution of SeO3(2- to elemental red Se(0, a high throughput colorimetric bioassay (Se-Assay was developed for parallel detection and quantification of nanoparticles (NPs cytotoxicity in a 96 well format. Thus, it has been concluded that the reducing power of the culture supernatant of strain JS-11 could be effectively exploited for developing a simple and environmental friendly method of Se-NPs synthesis. The results elucidated that the red colored Se° nanospheres may serve as a biosensor for nanotoxicity assessment, contemplating the inhibition of SeO3(2- bioreduction process in NPs treated bacterial cell culture supernatant, as a toxicity end point.

  14. Silica in higher plants.

    Science.gov (United States)

    Sangster, A G; Hodson, M J

    1986-01-01

    Opaline silica deposits are formed by many vascular (higher) plants. The capacity of these plants for silica absorption varies considerably according to genotype and environment. Plant communities exchange silica between soil and vegetation, especially in warmer climates. Silica deposition in epidermal cell walls offers mechanical and protective advantages. Biogenic silica particles from plants are also implicated in the causation of cancer. Recent techniques are reviewed which may aid in the identification of plant pathways for soluble silica movement to deposition sites and in the determination of ionic environments. Botanical investigations have focused on silicification of cell walls in relation to plant development, using scanning and transmission electron microscopy combined with X-ray microanalysis. Silica deposition in macrohair walls of the lemma of canary grass (Phalaris) begins at inflorescence emergence and closely follows wall thickening. The structure of the deposited silica may be determined by specific organic polymers present at successive stages of wall development. Lowering of transpiration by enclosure of Phalaris inflorescences in plastic bags reduced silica deposition in macrohairs. Preliminary freeze-substitution studies have located silicon, as well as potassium and chloride, in the cell vacuole and wall deposition sites during initial silicification.

  15. Sonochemical Synthesis of Er3+-Doped ZnO Nanospheres with Enhanced Upconversion Photoluminescence

    OpenAIRE

    Jun Geng; Guang-Hui Song; Jun-Jie Zhu

    2012-01-01

    Er3+-doped ZnO nanospheres have been synthesized via a sonochemical conversion process. The formation mechanism of these nanocrystals is connected with the sonochemical effect of ultrasound irradiation. The as-prepared Er3+ doped ZnO nanospheres show enhanced photoluminescence and upconversion photoluminescence properties compared with pure ZnO.

  16. Biodegradable mesoporous bioactive glass nanospheres for drug delivery and bone tissue regeneration

    Science.gov (United States)

    Wang, Xiaojian; Li, Wei

    2016-06-01

    Bioactive inorganic materials are attractive for hard tissue regeneration, and they are used as delivery vehicles for pharmaceutical molecules, scaffolds and components for bio-composites. We demonstrated mesoporous bioactive glass (BG) nanospheres that exhibited the capacity to deliver pharmaceutical molecules. Mesoporous BG nanospheres with variable Ca to Si ratios were synthesized using sol-gel chemistry. By controlling the hydrolysis and condensation conditions, the diameter of the mesoporous BG nanospheres was changed from 300 nm to 1500 nm. The porous structure and surface area of the BG nanospheres were shown to be dependent on their composition. The surface area of the BG nanospheres decreased from 400 ± 2 m2 g-1 to 56 ± 0.1 m2 g-1 when the Ca/Si ratio increased from 5 to 50 at.%. When the mesoporous BG nanospheres were loaded with ibuprofen (IBU), they exhibited a sustained release profile in simulated body fluid (SBF). In the meantime, the IBU-loaded BG nanospheres degraded in SBF, and induced apatite layer formation on the surface as a result of their good bioactivity. When the BG nanospheres were used as a composite filler to poly (ɛ-caprolactone) (PCL), they were shown to be effective at improving the in vitro bioactivity of PCL microspheres.

  17. Functionalization of Recombinant Amelogenin Nanospheres Allows Their Binding to Cellulose Materials.

    Science.gov (United States)

    Butler, Samuel J; Bülow, Leif; Bonde, Johan

    2016-10-01

    Protein engineering to functionalize the self-assembling enamel matrix protein amelogenin with a cellulose binding domain (CBD) is used. The purpose is to examine the binding of the engineered protein, rh174CBD, to cellulose materials, and the possibility to immobilize self-assembled amelogenin nanospheres on cellulose. rh174CBD assembled to nanospheres ≈35 nm in hydrodynamic diameter, very similar in size to wild type amelogenin (rh174). Uniform particles are formed at pH 10 for both rh174 and rh174CBD, but only rh174CBD nanospheres showes significant binding to cellulose (Avicel). Cellulose binding of rh174CBD is promoted when the protein is self-assembled to nanospheres, compared to being in a monomeric form, suggesting a synergistic effect of the multiple CBDs on the nanospheres. The amount of bound rh174CBD nanospheres reached ≈15 mg/g Avicel, which corresponds to 4.2 to 6.3 × 10(-7) mole/m(2) . By mixing rh174 and rh174CBD, and then inducing self-assembly, composite nanospheres with a high degree of cellulose binding can be formed, despite a lower proportion of rh174CBD. This demonstrates that amelogenin variants like rh174 can be incorporated into the nanospheres, and still retain most of the binding to cellulose. Engineered amelogenin nanoparticles can thus be utilized to construct a range of new cellulose based hybrid materials, e.g. for wound treatment.

  18. Self-assembly of Carboxyl Functionalized Polystyrene Nanospheres into Close-packed Monolayers via Chemical Adsorption

    Institute of Scientific and Technical Information of China (English)

    LI,Zhi-Wei(李志伟); ZHOU,Jing-Fang(周静芳); ZHANG,Zhi-Jun(张治军); DANG,Hong-Xin(党鸿辛)

    2004-01-01

    The polyacrylic acid functionalized polystyrene nanospheres were synthesized and self-assembled into irregular,densely packed monolayers in non-aqueous media. The polymer nanoparticles were chemically adhered to substrates. The morphologies of the resulting films were investigated. The impact of the volume fraction of alcohol in the mixed solvents on the particle adsorption and fabrication of nanosphere assembled films was examined.

  19. La2O3 hollow nanospheres for high performance lithium-ion rechargeable batteries.

    Science.gov (United States)

    Sasidharan, Manickam; Gunawardhana, Nanda; Inoue, Masamichi; Yusa, Shin-ichi; Yoshio, Masaki; Nakashima, Kenichi

    2012-03-28

    An efficient and simple protocol for synthesis of novel La(2)O(3) hollow nanospheres of size about 30 ± 2 nm using polymeric micelles is reported. The La(2)O(3) hollow nanospheres exhibit high charge capacity and cycling performance in lithium-ion rechargeable batteries (LIBs), which was scrutinized for the first time among the rare-earth oxides.

  20. MONODISPERSED AND NANOSIZED DENDRIMER/POLYSTYRENE LATEX PARTICLES

    Institute of Scientific and Technical Information of China (English)

    Changfeng Yi; Zushun Xu; Warren T. Ford

    2004-01-01

    Emulsion polymerization of styrene was carried out using dendrimer DAB-dendr-(NH2)64 as seed. The size and size distribution of the emulsion particles were characterized by transmission electron microscopy (TEM) and dynamic light scattering (DLS), and the effects of emulsion polymerization conditions on the preparation of emulsion particle were investigated. It has been found that the nanosized dendrimer/polystyrene polymer emulsion particles obtained were in the range of 26~64 nm in diameter, and were monodisperse; the size and size distribution of emulsion particles were influenced by the contents of dendrimer DAB-dendr-(NH2)64, emulsifier and initiator, as well as the pH value.

  1. Selection of quasi-monodisperse super-micron aerosol particles

    Science.gov (United States)

    Rösch, Michael; Pfeifer, Sascha; Wiedensohler, Alfred; Stratmann, Frank

    2014-05-01

    Size-segregated quasi monodisperse particles are essential for e.g. fundamental research concerning cloud microphysical processes. Commonly a DMA (Differential Mobility Analyzer) is used to produce quasi-monodisperse submicron particles. Thereto first, polydisperse aerosol particles are bipolarly charged by a neutralizer, and then selected according to their electrical mobility with the DMA [Knutson et al. 1975]. Selecting a certain electrical mobility with a DMA results in a particle size distribution, which contains singly charged particles as well as undesired multiply charged larger particles. Often these larger particles need to either be removed from the generated aerosol or their signals have to be corrected for in the data inversion and interpretation process. This problem becomes even more serious when considering super-micron particles. Here we will present two different techniques for generating quasi-monodisperse super-micron aerosol particles with no or only an insignificant number of larger sized particles being present. First, we use a combination of a cyclone with adjustable aerodynamic cut-off diameter and our custom-built Maxi-DMA [Raddatz et al. 2013]. The cyclone removes particles larger than the desired ones prior to mobility selection with the DMA. This results in a reduction of the number of multiply charged particles of up to 99.8%. Second, we utilize a new combination of cyclone and PCVI (Pumped Counterflow Virtual Impactor), which is based on purely inertial separation and avoids particle charging. The PCVI instrument was previously described by Boulter et al. (2006) and Kulkarni et al. (2011). With our two setups we are able to produce quasi-monodisperse aerosol particles in the diameter range from 0.5 to 4.4 µm without a significant number of larger undesired particles being present. Acknowledgements: This work was done within the framework of the DFG funded Ice Nucleation research UnIT (INUIT, FOR 1525) under WE 4722/1-1. References

  2. Monodisperse Clusters in Charged Attractive Colloids: Linear Renormalization of Repulsion.

    Science.gov (United States)

    Růžička, Štěpán; Allen, Michael P

    2015-08-11

    Experiments done on polydisperse particles of cadmium selenide have recently shown that the particles form spherical isolated clusters with low polydispersity of cluster size. The computer simulation model of Xia et al. ( Nat. Nanotechnol. 2011 , 6 , 580 ) explaining this behavior used a short-range van der Waals attraction combined with a variable long-range screened electrostatic repulsion, depending linearly on the volume of the clusters. In this work, we term this dependence "linear renormalization" of the repulsive term, and we use advanced Monte Carlo simulations to investigate the kinetically slowed down phase separation in a similar but simpler model. We show that amorphous drops do not dissolve and crystallinity evolves very slowly under linear renormalization, and we confirm that low polydispersity of cluster size can also be achieved using this model. The results indicate that the linear renormalization generally leads to monodisperse clusters.

  3. Solvent: A Key in Digestive Ripening for Monodisperse Au Nanoparticles

    Science.gov (United States)

    Wang, Peng; Qi, Xuan; Zhang, Xuemin; Wang, Tieqiang; Li, Yunong; Zhang, Kai; Zhao, Shuang; Zhou, Jun; Fu, Yu

    2017-01-01

    This work has mainly investigated the influence of the solvent on the nanoparticles distribution in digestive ripening. The experiments suggested that the solvents played a key role in digestive ripening of Au nanoparticles (Au NPs). For the benzol solvents, the resulting size distribution of Au NPs was inversely related to the solvent polarity. It may be interpreted by the low Gibbs free energy of nanoparticles in the high polarity medium, which was supposedly in favor of reducing the nanoparticles distribution. Through digestive ripening in the highly polar benzol solvent of p-chlorotoluene, monodisperse Au NPs with relative standard deviation (RSD) of 4.8% were achieved. This indicated that digestive ripening was an effective and practical way to prepare high-quality nanoparticles, which holds great promise for the nanoscience and nanotechnology.

  4. Structure and Hydration of Highly Branched, Monodisperse Phytoglycogen Nanoparticles

    Science.gov (United States)

    Atkinson, John; Nickels, Jonathan; Stanley, Christopher; Diallo, Souleymane; Katsaras, John; Dutcher, John

    Monodisperse phytoglycogen nanoparticles are a promising, new soft colloidal nanomaterial with many applications in the personal care, food, nutraceutical and pharmaceutical industries. These applications rely on exceptional properties that emerge from the highly branched structure of phytoglycogen and its interaction with water, such as extraordinarily high water retention, and low viscosity and exceptional stability in water. The structure and hydration of the nanoparticles was characterized using small angle neutron scattering (SANS) and quasielastic neutron scattering (QENS). SANS allowed us to determine the size of the nanoparticles, evaluate their radial density profile, quantify the particle-to-particle spacing, and determine their water content. The results show clearly that the nanoparticles are highly hydrated, with each nanoparticle containing 250% of its mass in water, and that aqueous dispersions approach a jamming transition at ~ 25% (w/w). QENS experiments provided an independent and consistent measure of the high level of hydration of the particles.

  5. Synthesis and performance of colloidal silica nano-abrasives with controllable size for chemical mechanical planarization.

    Science.gov (United States)

    Zhang, K L; Song, Z T; Wang, F; Wang, L Y; Feng, S L

    2009-02-01

    Under the analysis of particle growth mechanism, the monodisperse colloidal silica abrasives for chemical mechanical planarization (CMP) slurry were synthesized by the modified ion-exchanged and hydrothermal step-polymerization process. After the colloidal silica with controllable size was synthesized, its microstructure, stability and CMP performance was characterized and tested by SEM, HRTEM, Zeta potential Analyzer and CMP tester. Results show that the spherical, high stable (Zeta potential: -52.8 mV) colloidal silica with controllable size was achieved. About its CMP performance, the polishing rate for silicon double-side CMP is increased to be 317 nm/min and the polished surface roughness (RMS) was reduced to 0.32 nm.

  6. Synthesis and characterization of hollow magnetic nanospheres modified with Au nanoparticles for bio-encapsulation

    Science.gov (United States)

    Seisno, Satoshi; Suga, Kent; Nakagawa, Takashi; Yamamoto, Takao A.

    2017-04-01

    Hollow magnetic nanospheres modified with Au nanoparticles were successfully synthesized. Au/SiO2 nanospheres fabricated by a radiochemical process were used as templates for ferrite templating. After the ferrite plating process, Au/SiO2 templates were fully coated with magnetite nanoparticles. Dissolution of the SiO2 core lead to the formation of hollow magnetic nanospheres with Au nanoparticles inside. The hollow magnetic nanospheres consisted of Fe3O4 grains, with an average diameter of 60 nm, connected to form the sphere wall, inside which Au grains with an average diameter of 7.2 nm were encapsulated. The Au nanoparticles immobilized on the SiO2 templates contributed to the adsorption of the Fe ion precursor and/or Fe3O4 seeds. These hollow magnetic nanospheres are proposed as a new type of nanocarrier, as the Au grains could specifically immobilize biomolecules inside the hollow sphere.

  7. Characterization of polylactic co-glycolic acid nanospheres modified with PVA and DDAB

    Science.gov (United States)

    Mulia, Kamarza; Satyapertiwi, Dwiantari; Devina, Ranee; Krisanti, Elsa

    2017-02-01

    The common treatment for diabetic retinopathy is corticosteroids intravitreal injection that sometimes lead to complications. Dexamethasone-loaded polylactic co-glycolic acid (PLGA) nanospheres, modified with dioctadecyldimethylammonium bromide (DDAB) as the cationic surfactant, is expected to prolong drug retention time. Zeta potential of the PLGA nanospheres prepared using non-ionic surfactant PVA and DDAB confirmed the cationic surfactant increase the surface charge of the PLGA nanospheres. The optimal formulation based on the particle size and high positive surface charge was the PLGA-DDAB nanospheres. SEM analysis showed spherical morphology of the nanospheres having diameter 626.9 ± 98.01 nm positive zeta potential of +22.5 mV.

  8. Metallic Pb nanospheres in ultra-high temperature metamorphosed zircon from southern India

    Science.gov (United States)

    Whitehouse, M. J.; Kusiak, M. A.; Wirth, R.; Ravindra Kumar, G. R.

    2017-09-01

    A transmission electron microscope (TEM) study of Paleoproterozoic zircon that has experienced ultra-high temperature (UHT) metamorphism at ca. 570 Ma in the Kerala Khondalite Belt (KKB), southern India, documents the occurrence of metallic Pb nanospheres. These results permit comparison with a previous report from UHT zircon in Enderby Land, Antarctica, and allow further constraints to be placed on possible mechanisms for nanosphere formation. As in Enderby Land, the nanospheres in the KKB occur in non-metamict zircon, emphasising that radiogenic Pb redistribution can occur with only partial interconnectivity of radiation damaged zircon. In contrast, the nanospheres reported here are not closely associated with Si-rich glass inclusions, which is inconsistent with a silicate liquid-metal immiscibility model proposed in the earlier study. Formation of these Pb nanospheres effectively halts Pb-loss from zircon, even under extreme conditions, and can adversely affect geochronological interpretations due to decoupling of Pb from U.

  9. Mesoporous silica nanoparticles with organo-bridged silsesquioxane framework as innovative platforms for bioimaging and therapeutic agent delivery.

    Science.gov (United States)

    Du, Xin; Li, Xiaoyu; Xiong, Lin; Zhang, Xueji; Kleitz, Freddy; Qiao, Shi Zhang

    2016-06-01

    Mesoporous silica material with organo-bridged silsesquioxane frameworks is a kind of synergistic combination of inorganic silica, mesopores and organics, resulting in some novel or enhanced physicochemical and biocompatible properties compared with conventional mesoporous silica materials with pure Si-O composition. With the rapid development of nanotechnology, monodispersed nanoscale periodic mesoporous organosilica nanoparticles (PMO NPs) and organo-bridged mesoporous silica nanoparticles (MSNs) with various organic groups and structures have recently been synthesized from 100%, or less, bridged organosilica precursors, respectively. Since then, these materials have been employed as carrier platforms to construct bioimaging and/or therapeutic agent delivery nanosystems for nano-biomedical application, and they demonstrate some unique and/or enhanced properties and performances. This review article provides a comprehensive overview of the controlled synthesis of PMO NPs and organo-bridged MSNs, physicochemical and biocompatible properties, and their nano-biomedical application as bioimaging agent and/or therapeutic agent delivery system.

  10. Poly(furfuryl alcohol) nanospheres: a facile synthesis approach based on confinement effect of polymer and a template for synthesis of metal oxide hollow nanospheres

    Indian Academy of Sciences (India)

    Wei-Zhi Wang; Zhi-Qiang Li; Kong-Lin Wu; Ya-Jing Lu; Ya-Fei Xu; Xin-Jie Song

    2015-12-01

    This paper describes a facile hydrothermal approach to the large-scale synthesis of well-dispersed poly(furfuryl alcohol) (PFA) nanospheres with an average diameter of 350 nm in the presence of poly(vinyl pyrrolidone) (PVP). Scanning electron microscopy and transmission electron microscopy studies showed that different morphologies of PFA could be obtained by adjusting the ratio of PVP and furfuryl alcohol (FA). As a whole, the results demonstrate that PVP plays a key role in controlling the polymerization process of FA. The confinement effect of PVP is proposed to explain the formation process of PFA nanospheres. Furthermore, the as-prepared PFA nanospheres have a functional surface that allow them to act as an ideal template for fabricating metal oxide hollow nanospheres.

  11. High-Quality Hollow Closed-Pore Silica Antireflection Coatings Based on Styrene-Acrylate Emulsion @ Organic-Inorganic Silica Precursor.

    Science.gov (United States)

    Guo, Zhaolong; Zhao, Haixin; Zhao, Wei; Wang, Tao; Kong, Depeng; Chen, Taojing; Zhang, Xiaoyan

    2016-05-11

    Making use of a facile and low-cost way for the preparation of a hierarchically organized novel hollow closed-pore silica antireflective coating (CHAR) with tailored optical properties and a mechanical reliability is of great interest in the field of solar photovoltaic technology. The process mainly contains two aspects: (1) a styrene-acrylate emulsion @ organic-inorganic silica precursor (SA@OISP) core/shell hierarchical nanostructure, consisting of a sacrificial styrene-acrylate (SA) primary template, was fabricated using a sol-gel method; (2) the self-assembly of the nanostructures leads to SA@OISP nanospheres forming the high-quality hollow closed-pore silica antireflection coating (CHAR) by a dip-coating process and a subsequent calcination treatment. The resulting SA@OISP nanospheres have a mean diameter of 65.2 nm and contained a SA soft core with a mean diameter of approximately 54.8 nm and an organic-inorganic silica precursor (OISP) shell with a thickness of approximately 6-10 nm. Furthermore, the prepared CHAR film exhibited a high transmittance and good ruggedness. An average transmittance (TAV) of 97.64% was obtained, and the value is close to the ideal single-layered antireflection coating (98.09%) over a broad range of wavelengths (from 380 to 1100 nm). The CHAR film showed a stable TAV, with attenuation values of less than 0.8% and 0.43% after the abrasion test and the damp heat test, respectively. The conversion efficiency of the CHAR coating cover solar modules tends to be increased by 3.75%. The promising results obtained in this study suggest that the CHAR film was considered as an essential component of the solar module and were expected to provide additional solar energy harvest under extreme outdoor climates.

  12. Efficiency Enhancement of InGaN-Based Solar Cells via Stacking Layers of Light-Harvesting Nanospheres

    KAUST Repository

    Al-Amri, Amal M.

    2016-06-24

    An effective light-harvesting scheme for InGaN-based multiple quantum well solar cells is demonstrated using stacking layers of polystyrene nanospheres. Light-harvesting efficiencies on the solar cells covered with varied stacks of nanospheres are evaluated through numerical and experimental methods. The numerical simulation reveals that nanospheres with 3 stacking layers exhibit the most improved optical absorption and haze ratio as compared to those obtained by monolayer nanospheres. The experimental demonstration, agreeing with the theoretical analyses, shows that the application of 3-layer nanospheres improves the conversion efficiency of the solar cell by ~31%.

  13. Synthesis and characterization of bi-functional magneto-luminescent Fe₃O₄ @ SiO₂ @ NaLuF₄ :Eu³⁺ hybrid core / shell nanospheres

    Indian Academy of Sciences (India)

    JIGMET LADOL; HEENA KHAJURIA; HAQ NAWAZ SHEIKH; YUGAL KHAJURIA

    2016-07-01

    A step-wise synthetic method has been developed for the synthesis of multifunctional, magnetic luminescent nanocomposites with Fe₃O₄ nanospheres as the core encapsulated in silica and europium-doped sodium lutetium fluoride (NaLuF₄ :Eu³⁺) as the shell. X-ray powder diffraction (XRPD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), photoluminescence (PL), kinetics of luminescence decay and magnetic studies were used to characterize the structural, optical and magnetic properties of these nanospheres. SEM and TEM images define their spherical morphology with average crystallite size in the range of 90–180 nm. Ultraviolet excited photoluminescent properties of Eu³⁺ doped Fe₃O₄ @ SiO₂ @ NaLuF₄ nanospheres were investigated and impact of doping has been explored. Eu³⁺ as dopant ion induces highly efficient luminescence with average lifetime value of 6.235 ns. Fe₃O₄ magnetic core exhibits super- paramagnetic behavior at room temperature.

  14. Crystalline Silica Primer

    Science.gov (United States)

    ,

    1992-01-01

    Crystalline silica is the scientific name for a group of minerals composed of silicon and oxygen. The term crystalline refers to the fact that the oxygen and silicon atoms are arranged in a threedimensional repeating pattern. This group of minerals has shaped human history since the beginning of civilization. From the sand used for making glass to the piezoelectric quartz crystals used in advanced communication systems, crystalline silica has been a part of our technological development. Crystalline silica's pervasiveness in our technology is matched only by its abundance in nature. It's found in samples from every geologic era and from every location around the globe. Scientists have known for decades that prolonged and excessive exposure to crystalline silica dust in mining environments can cause silicosis, a noncancerous lung disease. During the 1980's, studies were conducted that suggested that crystalline silica also was a carcinogen. As a result of these findings, crystalline silica has been regulated under the Occupational Safety and Health Administration's (OSHA) Hazard Communication Standard (HCS). Under HCS, OSHAregulated businesses that use materials containing 0.1% or more crystalline silica must follow Federal guidelines concerning hazard communication and worker training. Although the HCS does not require that samples be analyzed for crystalline silica, mineral suppliers or OSHAregulated

  15. Silica Refractory Bricks

    Institute of Scientific and Technical Information of China (English)

    Yu Lingyan; Peng Xigao

    2011-01-01

    @@ 1.Scope This standard specifies the classification,technical requirements,test methods,quality appraisal procedures,packing,marking,transportation,storage,and quality certificate of silica refractory bricks.This standard is applicable to silica refractory bricks with single weight≤40 kg.

  16. Inter-laboratory comparison on the size and stability of monodisperse and bimodal synthetic reference particles for standardization of extracellular vesicle measurements

    Science.gov (United States)

    Nicolet, Anaïs; Meli, Felix; van der Pol, Edwin; Yuana, Yuana; Gollwitzer, Christian; Krumrey, Michael; Cizmar, Petr; Buhr, Egbert; Pétry, Jasmine; Sebaihi, Noham; de Boeck, Bert; Fokkema, Vincent; Bergmans, Rob; Nieuwland, Rienk

    2016-03-01

    In future, measurements of extracellular vesicles in body fluids could become a standard diagnostic tool in medicine. For this purpose, reliable and traceable methods, which can be easily applied in hospitals, have to be established. Within the European Metrological Research Project (EMRP) ‘Metrological characterization of micro-vesicles from body fluids as non-invasive diagnostic biomarkers’ (www.metves.eu), various nanoparticle reference materials were developed and characterized. We present results of an international comparison among four national metrology institutes and a university hospital. The size distributions of five monodisperse and two bimodal spherical particle samples with diameters ranging from 50 nm to 315 nm made out of silica and polystyrene were compared. Furthermore, the stability of the samples was verified over a period of 18 months. While monodisperse reference particle samples above a certain size level lead to good agreements of the size measurements among the different methods, small and bimodal samples show the limitations of current ‘clinical’ methods. All samples proved to be stable within the uncertainty of the applied methods.

  17. Synthesis of highly fluorescent silica nanoparticles in a reverse microemulsion through double-layered doping of organic fluorophores

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Hyojong, E-mail: hyojong@hallym.ac.kr; Pak, Joonsung [Hallym University, Department of Chemistry (Korea, Republic of)

    2013-05-15

    Water-soluble, highly fluorescent double-layered silica nanoparticles (FL-DLSN) have been successfully synthesized through a reverse (water-in-oil) microemulsion method. The microemulsion was prepared by mixing a surfactant (Brij35), co-surfactant, organic solvent, water, and fluorescein as an organic fluorophore. The sizes of the silica nanoparticles were successfully controlled in the reverse microemulsion using Brij35 by changing the water-to-Brij35 ratio and by adding HCl. Initially, tetraethylorthosilicate was hydrolyzed by adding NH{sub 4}OH as a catalyst and then polymerized to generate core fluorescent silica nanoparticles with fluorescein. 3-(Aminopropyl)triethoxysilane (APTS) was sequentially added into the reaction mixture, and reacted on the surface of pre-generated core silica nanoparticles to form the second layer in the form of a shell. The second silica layer that was derived from the condensation of APTS effectively protected the fluorescein dye within the silica matrix. This is a novel and simple synthetic approach to generate highly fluorescent, monodispersed silica nanoparticles by doping organic molecules into a silica matrix.Graphical Abstract.

  18. Electromagnetic and microwave absorbing properties of hollow carbon nanospheres

    Indian Academy of Sciences (India)

    Tianchun Zou; Haipeng Li; Naiqin Zhao; Chunsheng Shi

    2013-04-01

    A mass of hollow carbon nanospheres (HCNSs) was fabricated by chemical vapour deposition of methane over Ni/Al2O3 catalyst at 600 °C. The products were characterized with high-resolution transmission electron microscope images, and the results showed that the external diameter of the HCNSs was 5–90nm and the thickness of wall was about 10 nm. Microwave absorption of HCNSs/paraffin composites was mainly attributed to dielectric loss. The microwave-absorbing peaks of composites containing HCNSs shifts to low frequencies, and the bandwidth below −10 dB and minimum RL decrease with increasing thickness of HCNSs/paraffin composites.

  19. In-situ synthesis of monodisperse micro-nanospherical LiFePO4/carbon cathode composites for lithium-ion batteries

    Science.gov (United States)

    Gong, Hao; Xue, Hairong; Wang, Tao; He, Jianping

    2016-06-01

    The LiFePO4 is recognized as the promising cathode material, due to its high specific capacity, excellent, structural stability and environmental benignity. However, it is blamed for the low tap density and poor rate performance when served as the cathode materials for a long time. Here, the microspheric LiFePO4/C composites are successfully synthesized through a one-step in-situ solvothermal method combined with carbothermic reduction. These LiFePO4/C microspheres are assembled by LiFePO4 nanoparticles (∼100 nm) and uniformly coated by the carbon, which show a narrow diameter distribution of 4 μm. As a cathode material for lithium ion batteries, the LiFePO4/C composites can deliver an initiate charge capacity of 155 mAh g-1 and retain 90% of initial capacity after 200 cycles at 0.1 C. When cycled at high current densities up to 20 C, it shows a discharge capacity of ∼60 mAh g-1, exhibiting superior rate performance. The significantly improved electrochemical performance of LiFePO4/C composites material can be attributed to its special micro-nano hierarchical structure. Microspheric LiFePO4/C composites exhibit a high tap density about 1.3 g cm-3. What's more, the well-coated carbon insures the high electrical conductivity and the nano-sized LiFePO4/C particles shorten lithium ion transport, thus exhibiting the high specific capacity, high cycling stability and good rate performance.

  20. Asymmetric silica encapsulation toward colloidal Janus nanoparticles: a concave nanoreactor for template-synthesis of an electocatalytic hollow Pt nanodendrite

    Science.gov (United States)

    Koo, Jung Hun; Kim, Daun; Kim, Jin Goo; Jeong, Hwakyeung; Kim, Jongwon; Lee, In Su

    2016-07-01

    A novel reverse microemulsion strategy was developed to asymmetrically encapsulate metal-oxide nanoparticles in silica by exploiting the self-catalytic growth of aminosilane-containing silica at a single surface site. This strategy produced various colloidal Janus nanoparticles, including Au/Fe3O4@asy-SiO2, which were converted to an Au-containing silica nanosphere, Au@con-SiO2, by reductive Fe3O4 dissolution. The use of Au@con-SiO2 as a metal-growing nanoreactor allowed the templated synthesis of various noble-metal nanocrystals, including a hollow dendritic Pt nanoshell which exhibits significantly better electrocatalytic activities for the oxygen reduction reaction than commercial Pt/C catalysts.A novel reverse microemulsion strategy was developed to asymmetrically encapsulate metal-oxide nanoparticles in silica by exploiting the self-catalytic growth of aminosilane-containing silica at a single surface site. This strategy produced various colloidal Janus nanoparticles, including Au/Fe3O4@asy-SiO2, which were converted to an Au-containing silica nanosphere, Au@con-SiO2, by reductive Fe3O4 dissolution. The use of Au@con-SiO2 as a metal-growing nanoreactor allowed the templated synthesis of various noble-metal nanocrystals, including a hollow dendritic Pt nanoshell which exhibits significantly better electrocatalytic activities for the oxygen reduction reaction than commercial Pt/C catalysts. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr03557d

  1. Monodispersed Zinc Oxide Nanoparticle-Dye Dyads and Triads

    Energy Technology Data Exchange (ETDEWEB)

    Gladfelter, Wayne L. [Univ. of Minnesota, Minneapolis, MN (United States); Blank, David A. [Univ. of Minnesota, Minneapolis, MN (United States); Mann, Kent R. [Univ. of Minnesota, Minneapolis, MN (United States)

    2017-06-22

    events at a fundamental level. This was combined with the synthesis of a broad range of sensitizers that provide systematic variation of the energetics, excited state dynamics, structure and interfacial bonding. The key is that the monodisperse nature and high dispersibility of the ZnO NCs made these experiments reproducible; in essence, the measurements were on discrete molecular species rather than on the complicated mixtures that resulted from the typical fabrication of functional photovoltaic cells. The monodispersed nature of the NCs also allowed the use of quantum confinement to investigate the role of donor/acceptor energetic alignment in chemically identical systems. The results added significantly to our basic understanding of energy and charge transfer events at molecule-semiconductor interfaces and will help the R&D community realize zinc oxide's full potential in solar cell applications.

  2. Efficient thermolysis route to monodisperse Cu₂ZnSnS₄ nanocrystals with controlled shape and structure

    National Research Council Canada - National Science Library

    Zhang, Xiaoyan; Guo, Guobiao; Ji, Cheng; Huang, Kai; Zha, Chenyang; Wang, Yifeng; Shen, Liming; Gupta, Arunava; Bao, Ningzhong

    2014-01-01

    Monodisperse Cu2ZnSnS4 (CZTS) nanocrystals with tunable shape, crystalline phase, and composition are synthesized by efficient thermolysis of a single source precursor of mixed metal-oleate complexes in hot organic solvents...

  3. Cr/alpha-Cr2O3 monodispersed spherical core-shell particles based solar absorbers

    CSIR Research Space (South Africa)

    Khamlich, S

    2011-07-01

    Full Text Available Monodispersed spherical core-shell particles of Cr/alpha-Cr2O3 cermet ACG coatings investigated within this contribution could be successfully employed in thermal converters. Their selectivity depends on their chemical, physical and structural...

  4. Water-in-Water Emulsion Based Synthesis of Hydrogel Nanospheres with Tunable Release Kinetics

    Science.gov (United States)

    Aydın, Derya; Kızılel, Seda

    2016-06-01

    Poly(ethylene glycol) (PEG) micro/nanospheres have several unique advantages as polymer based drug delivery systems (DDS) such as tunable size, large surface area to volume ratio, and colloidal stability. Emulsification is one of the widely used methods for facile synthesis of micro/nanospheres. Two-phase aqueous system based on polymer-polymer immiscibility is a novel approach for preparation of water-in-water (w/w) emulsions. This method is promising for the synthesis of PEG micro/nanospheres for biological systems, since the emulsion is aqueous and do not require organic solvents or surfactants. Here, we report the synthesis of nano-scale PEG hydrogel particles using w/w emulsions using phase separation of dextran and PEG prepolymer. Dynamic light scattering (DLS) and scaning electron microscopy (SEM) results demonstrated that nano-scale hydrogel spheres could be obtained with this approach. We investigated the release kinetics of a model drug, pregabalin (PGB) from PEG nanospheres and demonstrated the influence of polymerization conditions on loading and release of the drug as well as the morphology and size distribution of PEG nanospheres. The experimental drug release data was fitted to a stretched exponential function which suggested high correlation with experimental results to predict half-time and drug release rates from the model equation. The biocompatibility of nanospheres on human dermal fibroblasts using cell-survival assay suggested that PEG nanospheres with altered concentrations are non-toxic, and can be considered for controlled drug/molecule delivery.

  5. Graphene-wrapped ZnO nanospheres as a photocatalyst for high performance photocatalysis

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Da, E-mail: dchen_80@hotmail.com [College of Materials Science & Engineering, China Jiliang University, Hangzhou 310018 (China); Wang, Dongfang; Ge, Qisheng; Ping, Guangxing [College of Materials Science & Engineering, China Jiliang University, Hangzhou 310018 (China); Fan, Meiqiang, E-mail: fanmeiqiang@126.com [College of Materials Science & Engineering, China Jiliang University, Hangzhou 310018 (China); Qin, Laishun [College of Materials Science & Engineering, China Jiliang University, Hangzhou 310018 (China); Bai, Liqun [School of Sciences, Zhejiang Agriculture and Forestry University, Hangzhou 311300 (China); Lv, Chunju; Shu, Kangying [College of Materials Science & Engineering, China Jiliang University, Hangzhou 310018 (China)

    2015-01-01

    In this work, graphene-wrapped ZnO nanospheres (ZnO–graphene nanocomposites) were prepared by a simple facile lyophilization method, followed by thermal treatment process. ZnO nanospheres with the size of about 100–400 nm, composed of numerous nanocrystals with hexagonal wurtzite structure, were well separated from each other and wrapped with transparent graphene sheets. Compared to ZnO nanospheres, the ZnO–graphene nanocomposites showed a significant enhancement in the photodegradation of methylene blue. This enhanced photocatalytic activity could be attributed to their favorable dye-adsorption affinity and increased optical absorption as well as the efficient charge transfer of the photogenerated electrons in the conduction band of ZnO to graphene. Thus, this work could provide a facile and low-cost method for the development of graphene-based nanocomposites with promising applications in photocatalysis, solar energy conversion, sensing, and so on. - Highlights: • Graphene-wrapped ZnO nanospheres were prepared by a facile lyophilization method. • ZnO nanospheres were separated from each other and wrapped with 2D graphene sheets. • Graphene-wrapped ZnO nanospheres exhibited superior photocatalytic activities. • The photocatalytic mechanisms of graphene-wrapped ZnO nanospheres were discussed.

  6. Facile fabrication of mesoporous ZnO nanospheres for the controlled delivery of captopril

    Science.gov (United States)

    Bakrudeen, Haja Bava; Tsibouklis, John; Reddy, Boreddy S. R.

    2013-03-01

    In the present study, to formulate captopril in a hierarchical porous structure of ZnO nanospheres by means of the soluble-starch-insertion method, state of drug carrier delivery toward oral route and the mode of delivery in suitable medium. Mesoporous ZnO nanospheres were synthesized by simple soluble-starch-insertion method, followed by loading of captopril using ultrasonic force. The materials were characterized by PXRD, SEM, FESEM, TEM, TGA, FT-IR, and BET analyses, and biocompatibility studies. Captopril-loaded porous ZnO nanospheres were evaluated as in vitro drug-release studies and its kinetic models. Crystallite plane arrangement, functional groups, materials morphology, and porosity of porous ZnO nanospheres were confirmed. Larger surface area and distribution in constrained pores on its surface make the nanospheres suitable for high drug loading of captopril. The ZnO nanocrystallites have given porous properties on the spherical surface leads to the drug adsorption. The loading and release studies (in vitro in simulated gastric and intestinal fluids) have shown that both were affected by the mesoporous nanospheres' surface properties of the ZnO materials and its biocompatibility has also been proved. Therefore, the in vitro experiments have indicated the considerable promise of mesoporous ZnO nanospheres, fabricated by the soluble-starch-insertion method acting as a biocompatible carrier for the controlled delivery of captopril in oral route of administration.

  7. Facile fabrication of mesoporous ZnO nanospheres for the controlled delivery of captopril

    Energy Technology Data Exchange (ETDEWEB)

    Bakrudeen, Haja Bava [Central Leather Research Institute (Council of Scientific and Industrial Research), Industrial Chemistry Laboratory (India); Tsibouklis, John [University of Portsmouth, School of Pharmacy and Biomedical Sciences (United Kingdom); Reddy, Boreddy S. R., E-mail: induchem2000@yahoo.com [Central Leather Research Institute (Council of Scientific and Industrial Research), Industrial Chemistry Laboratory (India)

    2013-03-15

    In the present study, to formulate captopril in a hierarchical porous structure of ZnO nanospheres by means of the soluble-starch-insertion method, state of drug carrier delivery toward oral route and the mode of delivery in suitable medium. Mesoporous ZnO nanospheres were synthesized by simple soluble-starch-insertion method, followed by loading of captopril using ultrasonic force. The materials were characterized by PXRD, SEM, FESEM, TEM, TGA, FT-IR, and BET analyses, and biocompatibility studies. Captopril-loaded porous ZnO nanospheres were evaluated as in vitro drug-release studies and its kinetic models. Crystallite plane arrangement, functional groups, materials morphology, and porosity of porous ZnO nanospheres were confirmed. Larger surface area and distribution in constrained pores on its surface make the nanospheres suitable for high drug loading of captopril. The ZnO nanocrystallites have given porous properties on the spherical surface leads to the drug adsorption. The loading and release studies (in vitro in simulated gastric and intestinal fluids) have shown that both were affected by the mesoporous nanospheres' surface properties of the ZnO materials and its biocompatibility has also been proved. Therefore, the in vitro experiments have indicated the considerable promise of mesoporous ZnO nanospheres, fabricated by the soluble-starch-insertion method acting as a biocompatible carrier for the controlled delivery of captopril in oral route of administration.Graphical Abstract.

  8. Europium-doped amorphous calcium phosphate porous nanospheres: preparation and application as luminescent drug carriers

    Directory of Open Access Journals (Sweden)

    Zhang Kui-Hua

    2011-01-01

    Full Text Available Abstract Calcium phosphate is the most important inorganic constituent of biological tissues, and synthetic calcium phosphate has been widely used as biomaterials. In this study, a facile method has been developed for the fabrication of amorphous calcium phosphate (ACP/polylactide-block-monomethoxy(polyethyleneglycol hybrid nanoparticles and ACP porous nanospheres. Europium-doping is performed to enable photoluminescence (PL function of ACP porous nanospheres. A high specific surface area of the europium-doped ACP (Eu3+:ACP porous nanospheres is achieved (126.7 m2/g. PL properties of Eu3+:ACP porous nanospheres are investigated, and the most intense peak at 612 nm is observed at 5 mol% Eu3+ doping. In vitro cytotoxicity experiments indicate that the as-prepared Eu3+:ACP porous nanospheres are biocompatible. In vitro drug release experiments indicate that the ibuprofen-loaded Eu3+:ACP porous nanospheres show a slow and sustained drug release in simulated body fluid. We have found that the cumulative amount of released drug has a linear relationship with the natural logarithm of release time (ln(t. The Eu3+:ACP porous nanospheres are bioactive, and can transform to hydroxyapatite during drug release. The PL properties of drug-loaded nanocarriers before and after drug release are also investigated.

  9. Preparation of Monodisperse Nanoparticle of Layered Double Hydroxides and Polyoxyethylene Sulfate

    Institute of Scientific and Technical Information of China (English)

    XU Huizhong; QIN Lianjie; ZHANG Hong; YANG Qinzheng; YANG Jing

    2005-01-01

    In order to obtain the bio-molecule/ LDHs nanocomposites having regular crystal structure,three nanocomposites of layered double hydroxides and polyoxyethylene sulfates were prepared by ion-exchange method. TEM analysis reveals that the monodisperse rigid .sphere of approximately 200 nm in diameter could be gotten when the intergallery anion was PEGS-400. Such monodisperse nanoparticle could be used as a promising precursor for preparing bio-molecule/LDHs nanocomposites.

  10. Sustained Ocular Delivery of Ciprofloxacin Using Nanospheres and Conventional Contact Lens Materials

    Science.gov (United States)

    Garhwal, Rahul; Shady, Sally F.; Ellis, Edward J.; Ellis, Jeanne Y.; Leahy, Charles D.; McCarthy, Stephen P.; Crawford, Kathryn S.

    2012-01-01

    Purpose. To formulate conventional contact lenses that incorporate nanosphere-encapsulated antibiotic and demonstrate that the lenses provide for sustained antibacterial activity. Methods. A copolymer composed of pullulan and polycaprolactone (PCL) was used to synthesize core-shell nanospheres that encapsulated ciprofloxacin. Bactericidal activity of the nanosphere-encapsulated ciprofloxacin (nanosphere/cipro) was tested by using liquid cultures of either Staphylococcus aureus or Pseudomonas aeruginosa. Nanosphere/cipro was then incorporated into HEMA-based contact lenses that were tested for growth inhibition of S. aureus or P. aeruginosa in liquid cultures inoculated daily with fresh bacteria. Lens designs included thin or thick lenses incorporating nanosphere/cipro and ciprofloxacin-HCl-soaked Acuvue lenses (Acuvue; Johnson & Johnson Vision Care, Inc., Jacksonville, FL). Results. Less than 2 μg/mL of nanosphere/cipro effectively inhibited the proliferation of cultures inoculated with 107 or 108 bacteria/mL of S. aureus and P. aeruginosa, respectively. HEMA-based contact lenses polymerized with nanosphere/cipro were transparent, effectively inhibited the proliferation of greater than 107/mL of bacteria added daily over 3 days of culture, and killed up to 5 × 109 total microbes in a single inoculation. A thicker lens design provided additional inhibition of bacterial growth for up to 96 hours. Conclusions. Core-shell nanospheres loaded with an antibiotic can be incorporated into a conventional, transparent contact lens and provide for sustained and effective bactericidal activity and thereby provide a new drug delivery platform for widespread use in treating ocular disorders. PMID:22266514

  11. Single-Crystal MgO Hollow Nanospheres Formed in RF Impulse Discharge Plasmas

    Directory of Open Access Journals (Sweden)

    Satoru Iizuka

    2012-01-01

    Full Text Available Spherical MgO nanoparticles with a hollow inside, that is, MgO hollow nanospheres, were created in Ar/O2 plasma produced by radio frequency (RF impulse discharge using a Mg rod electrode. The hollow nanospheres were found on the SiO2 plates placed near the powered Mg electrode. The electron refraction pattern showed that each nanosphere was made of a single crystal of MgO. Since the shape was spherical, these nanoparticles seemed to be created during the levitation in the plasma without touching any walls. The formation mechanism with a quasiliquid cooling model was also discussed.

  12. Facile Hydrothermal Synthesis of SnO2 Nanospheres as Photocatalysts

    OpenAIRE

    Wenquan Hu; Xiaoguang Yuan

    2017-01-01

    Large amounts of SnO2 nanospheres are successfully synthesized through a simple and effective hydrothermal method. The as-synthesized products consist of numerous small SnO2 nanocrystals with an average diameter of 40 nm. The as-prepared SnO2 nanospheres are further used as the photocatalysts for photodegrading several organic dyes (methylene blue, methyl orange, Congo red, and rhodamine B) under UV light irradiation. The photocatalytic results show that the as-synthesized SnO2 nanospheres po...

  13. Nickel titanates hollow shells: nanosphere, nanorod, and their photocatalytic properties.

    Science.gov (United States)

    Li, Qiuye; Xing, Yangyang; Zong, Lanlan; Li, Rui; Yang, Jianjun

    2013-01-01

    Two kinds of hollow shell structured nickel titanates (nanosphere, nanorod) were prepared by the microwave-assisted hydrothermal method using carbon material as the template. Their phase structure, morphology, and optical properties were well characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV-vis diffuse reflectance spectroscopy (DRS). Comparing with the template-free NiTiO3 (NiTiO3-TF), the two kinds of hollow shell structured NiTiO3 have larger Brunauer-Emmet-Teller (BET) surface areas. Both NiTiO3 nanosphere (NiTiO3-NS) and nanorod (NiTiO3-NR) showed remarkably photocatalytic H2 evolution from the methanol aqueous solution under full-arc lamp and visible light. Additional, their photocatalytic activities were also determined by photo-degradation of methyl blue (MB), and the degradation yield reached nearly 100% within 100 min on NiTiO3-NR under visible light. Whatever in photocatalytic H2 evolution or MB degradation, their photocatalytic activities all followed the order: NiTiO3-NR > NiTiO3-NS > NiTiO3-TF. The higher photocatalytic activities of the hollow shelled NiTiO3 should be due to their larger BET surface areas and more utilization of the incident light.

  14. Periodic jetting and monodisperse jet drops from oblique gas injection

    Science.gov (United States)

    McRae, Oliver; Gaillard, Antoine; Bird, James C.

    2017-07-01

    When air is blown in a straw or tube near an air-liquid interface, typically one of two behaviors is observed: a dimple in the liquid's surface, or a frenzy of sputtering bubbles, waves, and spray. Here we report and characterize an intermediate regime that can develop when a confined air jet enters the interface at an angle. This regime is oscillatory with a distinct characteristic frequency and can develop periodic angled jets that can break up into monodisperse aerosols. The underlying mechanisms responsible for this highly periodic regime are not well understood. Here we flow a continuous stream of gas through a tube near a liquid surface, observing both optically and acoustically the deformation of the liquid-air interface as various parameters are systematically adjusted. We show that the Kelvin-Helmholtz instability is responsible for the inception of waves within a cavity formed by the gas. Inertia, gravity, and capillary forces both shape the cavity and govern the frequency and amplitude of these gas-induced cavity waves. The flapping cavity focuses the waves into a series of periodic jets that can break up into droplets following the Rayleigh-Plateau instability. We present scaling arguments to rationalize the fundamental frequencies driving this system, as well as the conditions that bound the periodic regime. These frequencies and conditions compare well with our experimental results.

  15. Jamming of Monodisperse Cylindrical Grains in Featureless Vertical Channels

    Science.gov (United States)

    Friedl, Nicholas; Baxter, G. William

    2014-03-01

    We study jamming of low aspect-ratio cylindrical Delrin grains falling through a featureless vertical channel under the influence of gravity. These grains have an aspect-ratio less than two (H/D aspirin tablets, 35mm film canisters, poker chips, or coins. Monodisperse grains are allowed to fall under the influence of gravity through a uniform channel of square cross-section where the channel width is greater than the grain size and constant along the length of the channel. No combination of grain heights and diameters is equal to the channel width. Collections of grains sometimes form jams, stable structures in which the grains are supported by the channel walls and not by grains or walls beneath them. The probability of a jam occurring and the jam's strength are influenced by the grain dimensions and channel width. We will present experimental measurements of the jamming probability and jam strength and discuss the relationship of these results to other experiments and theories. Supported by an Undergraduate Research Grant from Penn State Erie, The Behrend College.

  16. Biotemplate synthesis of monodispersed iron phosphate hollow microspheres.

    Science.gov (United States)

    Cao, Feng; Li, Dongxu

    2010-03-01

    Monodispersed iron phosphate hollow microspheres with a high degree of crystallization were prepared through a facile in situ deposition method using rape pollen grains as a biotemplate. The functional group on the surface of the pollen grains could adsorb Fe(3+), which provided the nucleation sites for growth of iron phosphate nanoparticles. After being sintered at 600 degrees C for 10 h, the pollen grains were removed and iron phosphate hollow microspheres were obtained. A scanning electron microscope and x-ray diffraction were applied to characterize the morphology and crystalline structure of the pollen grains, iron phosphate-coated pollen grains and iron phosphate hollow microspheres. Differential scanning calorimetry and thermogravity analyses were performed to investigate the thermal behavior of the iron phosphate-coated pollen grains during the calcinations. Energy dispersive spectroscopy and Fourier transform infrared spectroscopy were utilized to investigate the interaction between the pollen grains and iron phosphate. The effect of the pollen wall on the surface morphology of these iron phosphate hollow microspheres was also proven in this work.

  17. Facile Synthesis of Monodisperse Gold Nanocrystals Using Virola oleifera

    Science.gov (United States)

    Milaneze, Bárbara A.; Oliveira, Jairo P.; Augusto, Ingrid; Keijok, Wanderson J.; Côrrea, Andressa S.; Ferreira, Débora M.; Nunes, Otalíbio C.; Gonçalves, Rita de Cássia R.; Kitagawa, Rodrigo R.; Celante, Vinícius G.; da Silva, André Romero; Pereira, Ana Claudia H.; Endringer, Denise C.; Schuenck, Ricardo P.; Guimarães, Marco C. C.

    2016-10-01

    The development of new routes and strategies for nanotechnology applications that only employ green synthesis has inspired investigators to devise natural systems. Among these systems, the synthesis of gold nanoparticles using plant extracts has been actively developed as an alternative, efficient, cost-effective, and environmentally safe method for producing nanoparticles, and this approach is also suitable for large-scale synthesis. This study reports reproducible and completely natural gold nanocrystals that were synthesized using Virola oleifera extract. V. oleifera resin is rich in epicatechin, ferulic acid, gallic acid, and flavonoids (i.e., quercetin and eriodictyol). These gold nanoparticles play three roles. First, these nanoparticles exhibit remarkable stability based on their zeta potential. Second, these nanoparticles are functionalized with flavonoids, and third, an efficient, economical, and environmentally friendly mechanism can be employed to produce green nanoparticles with organic compounds on the surface. Our model is capable of reducing the resin of V. oleifera, which creates stability and opens a new avenue for biological applications. This method does not require painstaking conditions or hazardous agents and is a rapid, efficient, and green approach for the fabrication of monodisperse gold nanoparticles.

  18. Ultrasonically Aided Electrospray source for monodisperse, charged nanoparticles

    Science.gov (United States)

    Song, Weidong

    This dissertation presents a new method of producing nearly monodisperse electrospray using charged capillary standing waves. This method, based on the Ultrasonically Aided Electrospraying (UAE) technology concept invented by the author, includes the steps of dispensing a liquid on the top surface of a diaphragm so as to form a liquid film on the surface of the diaphragm, setting the diaphragm into vibration using piezoelectric transducers so as to induce capillary standing waves in the liquid film, applying electric charge to the capillary standing waves so that electrospray is extracted from the crests of the capillary standing waves. Theoretical analysis on the formation of charged particles from charged capillary standing waves at critically stable condition is performed. An experimental UAE system is designed, built, and tested and the performance of this new technology concept is assessed. Experimental results validate the capabilities of the UAE concept. The method has several applications including electric space propulsion, nano particulate technologies, nanoparticle spray coating and painting techniques, semiconductor fabrication and biomedical processes. Two example applications in electric space propulsion and nanoparticle spray coating are introduced.

  19. Spark Ignition of Monodisperse Fuel Sprays. Ph.D. Thesis

    Science.gov (United States)

    Danis, Allen M.; Cernansky, Nicholas P.; Namer, Izak

    1987-01-01

    A study of spark ignition energy requirements was conducted with a monodisperse spray system allowing independent control of droplet size, equivalent ratio, and fuel type. Minimum ignition energies were measured for n-heptane and methanol sprays characterized at the spark gap in terms of droplet diameter, equivalence ratio (number density) and extent of prevaporization. In addition to sprays, minimum ignition energies were measured for completely prevaporized mixtures of the same fuels over a range of equivalence ratios to provide data at the lower limit of droplet size. Results showed that spray ignition was enhanced with decreasing droplet size and increasing equivalence ratio over the ranges of the parameters studied. By comparing spray and prevaporized ignition results, the existence of an optimum droplet size for ignition was indicated for both fuels. Fuel volatility was seen to be a critical factor in spray ignition. The spray ignition results were analyzed using two different empirical ignition models for quiescent mixtures. Both models accurately predicted the experimental ignition energies for the majority of the spray conditions. Spray ignition was observed to be probabilistic in nature, and ignition was quantified in terms of an ignition frequency for a given spark energy. A model was developed to predict ignition frequencies based on the variation in spark energy and equivalence ratio in the spark gap. The resulting ignition frequency simulations were nearly identical to the experimentally observed values.

  20. Biotemplate synthesis of monodispersed iron phosphate hollow microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Cao Feng; Li Dongxu, E-mail: dongxuli@njut.edu.c [College of Materials Science and Engineering, Nanjing University of Technology, Jiangsu Nanjing 210009 (China)

    2010-03-15

    Monodispersed iron phosphate hollow microspheres with a high degree of crystallization were prepared through a facile in situ deposition method using rape pollen grains as a biotemplate. The functional group on the surface of the pollen grains could adsorb Fe{sup 3+}, which provided the nucleation sites for growth of iron phosphate nanoparticles. After being sintered at 600 deg. C for 10 h, the pollen grains were removed and iron phosphate hollow microspheres were obtained. A scanning electron microscope and x-ray diffraction were applied to characterize the morphology and crystalline structure of the pollen grains, iron phosphate-coated pollen grains and iron phosphate hollow microspheres. Differential scanning calorimetry and thermogravity analyses were performed to investigate the thermal behavior of the iron phosphate-coated pollen grains during the calcinations. Energy dispersive spectroscopy and Fourier transform infrared spectroscopy were utilized to investigate the interaction between the pollen grains and iron phosphate. The effect of the pollen wall on the surface morphology of these iron phosphate hollow microspheres was also proven in this work.

  1. Monodisperse droplet generation for microscale mass transfer studies

    Science.gov (United States)

    Roberts, Christine; Rao, Rekha; Grillet, Anne; Jove-Colon, Carlos; Brooks, Carlton; Nemer, Martin

    2011-11-01

    Understanding interfacial mass transport on a droplet scale is essential for modeling liquid-liquid extraction processes. A thin flow-focusing microfluidic channel is evaluated for generating monodisperse liquid droplets for microscale mass transport studies. Surface treatment of the microfluidic device allows creation of both oil in water and water in oil emulsions, facilitating a large parameter study of viscosity and flow rate ratios. The unusually thin channel height promotes a flow regime where no droplets form. Through confocal microscopy, this regime is shown to be highly influenced by the contact angle of the liquids with the channel. Drop sizes are found to scale with a modified capillary number. Liquid streamlines within the droplets are inferred by high speed imagery of microparticles dispersed in the droplet phase. Finally, species mass transfer to the droplet fluid is quantitatively measured using high speed imaging. Sandia National Laboratories is a multi-program laboratory operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85.

  2. Heat- and mass-transport in aqueous silica nanofluids

    Science.gov (United States)

    Turanov, A. N.; Tolmachev, Yuriy V.

    2009-10-01

    Using the transient hot wire and pulsed field gradient nuclear magnetic resonance methods we determined the thermal conductivity and the solvent self-diffusion coefficient (SDC) in aqueous suspensions of quasi-monodisperse spherical silica nanoparticles. The thermal conductivity was found to increase at higher volume fraction of nanoparticles in accordance with the effective medium theory albeit with a smaller slope. On the other hand, the SDC was found to decrease with nanoparticle volume fraction faster than predicted by the effective medium theory. These deviations can be explained by the presence of an interfacial heat-transfer resistance and water retention by the nanoparticles, respectively. We found no evidence for anomalous enhancement in the transport properties of nanofluids reported earlier by other groups.

  3. Rational design of carbon network cross-linked Si-SiC hollow nanosphere as anode of lithium-ion batteries

    Science.gov (United States)

    Wen, Zhenhai; Lu, Ganhua; Cui, Shumao; Kim, Haejune; Ci, Suqin; Jiang, Junwei; Hurley, Patrick T.; Chen, Junhong

    2013-12-01

    This study aims to realize controllable synthesis of Si-based nanostructures from common and easily accessible silica nanoparticles and to study their component/structure-dependent electrochemical performance as an anode of lithium-ion batteries (LIBs). To this end, a controllable route based on deliberate design has been developed to prepare hollow Si-based nanospheres with tunable composition and crystal structure at the nanoscale. The synthesis process started with coating silica nanoparticles with a carbonaceous polymer with a controllable thickness followed by magnesiothermic reduction. An Si-SiC-C composite was finally produced with a unique hollow sphere structure featuring Si-SiC nanoparticles encapsulated by a cross-linked carbon film network. In addition to the scalability of the synthetic route, the resulting composite exhibits a number of advantageous properties, including excellent electrical conductivity, highly accessible surfaces, structural coherence, and a favorable structure for the formation of a stable solid-electrolyte interphase, which makes it attractive and promising for advanced anode materials of LIBs.This study aims to realize controllable synthesis of Si-based nanostructures from common and easily accessible silica nanoparticles and to study their component/structure-dependent electrochemical performance as an anode of lithium-ion batteries (LIBs). To this end, a controllable route based on deliberate design has been developed to prepare hollow Si-based nanospheres with tunable composition and crystal structure at the nanoscale. The synthesis process started with coating silica nanoparticles with a carbonaceous polymer with a controllable thickness followed by magnesiothermic reduction. An Si-SiC-C composite was finally produced with a unique hollow sphere structure featuring Si-SiC nanoparticles encapsulated by a cross-linked carbon film network. In addition to the scalability of the synthetic route, the resulting composite exhibits a

  4. Porous silicon nanocrystals in a silica aerogel matrix

    Science.gov (United States)

    Amonkosolpan, Jamaree; Wolverson, Daniel; Goller, Bernhard; Polisski, Sergej; Kovalev, Dmitry; Rollings, Matthew; Grogan, Michael D. W.; Birks, Timothy A.

    2012-07-01

    Silicon nanoparticles of three types (oxide-terminated silicon nanospheres, micron-sized hydrogen-terminated porous silicon grains and micron-size oxide-terminated porous silicon grains) were incorporated into silica aerogels at the gel preparation stage. Samples with a wide range of concentrations were prepared, resulting in aerogels that were translucent (but weakly coloured) through to completely opaque for visible light over sample thicknesses of several millimetres. The photoluminescence of these composite materials and of silica aerogel without silicon inclusions was studied in vacuum and in the presence of molecular oxygen in order to determine whether there is any evidence for non-radiative energy transfer from the silicon triplet exciton state to molecular oxygen adsorbed at the silicon surface. No sensitivity to oxygen was observed from the nanoparticles which had partially H-terminated surfaces before incorporation, and so we conclude that the silicon surface has become substantially oxidised. Finally, the FTIR and Raman scattering spectra of the composites were studied in order to establish the presence of crystalline silicon; by taking the ratio of intensities of the silicon and aerogel Raman bands, we were able to obtain a quantitative measure of the silicon nanoparticle concentration independent of the degree of optical attenuation.

  5. Solution-based carbohydrate synthesis of individual solid, hollow, and porous carbon nanospheres using spray pyrolysis.

    Science.gov (United States)

    Wang, Chengwei; Wang, Yuan; Graser, Jake; Zhao, Ran; Gao, Fei; O'Connell, Michael J

    2013-12-23

    A facile and scalable solution-based, spray pyrolysis synthesis technique was used to synthesize individual carbon nanospheres with specific surface area (SSA) up to 1106 m(2)/g using a novel metal-salt catalyzed reaction. The carbon nanosphere diameters were tunable from 10 nm to several micrometers by varying the precursor concentrations. Solid, hollow, and porous carbon nanospheres were achieved by simply varying the ratio of catalyst and carbon source without using any templates. These hollow carbon nanospheres showed adsorption of to 300 mg of dye per gram of carbon, which is more than 15 times higher than that observed for conventional carbon black particles. When evaluated as supercapacitor electrode materials, specific capacitances of up to 112 F/g at a current density of 0.1 A/g were observed, with no capacitance loss after 20,000 cycles.

  6. Resonant mixing of optical orbital and spin angular momentum by using chiral silicon nanosphere clusters.

    Science.gov (United States)

    Al-Jarro, Ahmed; Biris, Claudiu G; Panoiu, Nicolae C

    2016-04-01

    We present an in-depth analysis of the resonant intermixing between optical orbital and spin angular momentum of Laguerre-Gaussian (LG) beams, mediated by chiral clusters made of silicon nanospheres. In particular, we establish a relationship between the spin and orbital quantum numbers characterizing the LG beam and the order q of the rotation symmetry group q of the cluster of nanospheres for which resonantly enhanced coupling between the two components of the optical angular momentum is observed. Thus, similar to the case of diffraction grating-mediated transfer of linear momentum between optical beams, we demonstrate that clusters of nanospheres that are invariant to specific rotation transformations can efficiently transfer optical angular momentum between LG beams with different quantum numbers. We also discuss the conditions in which the resonant interaction between LG beams and a chiral cluster of nanospheres leads to the generation of superchiral light.

  7. Fluorescent QDs-polystyrene composite nanospheres for highly efficient and rapid protein antigen detection

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Changhua; Mao, Mao [Henan University, Key Laboratory for Special Functional Materials of the Ministry of Education (China); Yuan, Hang [Tsinghua University, Life Science Division, Graduate School at Shenzhen (China); Shen, Huaibin [Henan University, Key Laboratory for Special Functional Materials of the Ministry of Education (China); Wu, Feng; Ma, Lan, E-mail: malan@sz.tsinghua.edu.cn [Tsinghua University, Life Science Division, Graduate School at Shenzhen (China); Li, Lin Song, E-mail: lsli@henu.edu.cn [Henan University, Key Laboratory for Special Functional Materials of the Ministry of Education (China)

    2013-09-15

    In this paper, high-quality carboxyl-functionalized fluorescent (red, green, and blue emitting) nanospheres (46-103 nm) consisting of hydrophobic quantum dots (QDs) and polystyrene were prepared by a miniemulsion polymerization approach. This miniemulsion polymerization approach induced a homogeneous distribution and high aqueous-phase transport efficiency of fluorescent QDs in composite nanospheres, which proved the success of our encoding QDs strategy. The obtained fluorescent nanospheres exhibited high stability in aqueous solution under a wide range of pH, different salt concentrations, PBS buffer, and thermal treatment at 80 Degree-Sign C. Based on the red emitting composite nanosphere, we performed fluorescent lateral flow immunoassay (LFIA) strips for high-sensitivity and rapid alpha-fetal protein detection. The detection limit reached 0.1 ng/mL, which was 200 times higher than commercial colloidal gold-labeled LFIA strips, and it reached similar detection level in enzyme-linked immunosorbent assay kit.

  8. Soft-templated synthesis of mesoporous carbon nanospheres and hollow carbon nanofibers

    Science.gov (United States)

    Cheng, Youliang; Li, Tiehu; Fang, Changqing; Zhang, Maorong; Liu, Xiaolong; Yu, Ruien; Hu, Jingbo

    2013-10-01

    Using coal tar pitch based amphiphilic carbonaceous materials (ACMs) as the precursor and amphiphilic triblock copolymer Plutonic P123 as the only soft template, carbon nanospheres with partially ordered mesopores and hollow carbon nanofibers were synthesized. The concentration of P123, cp, and the mass ratio of P123 to ACM, r, are the key parameters of controlling the shape of the as-prepared products. Mesoporous carbon nanospheres with diameter of 30-150 nm were prepared under the condition of cp = 13.3 g/L and r = 1.2. When cp = 26.7 g/L and r = 2, hollow carbon nanofibers with diameters of 50-200 nm and mesopores/macropores were obtained. Carbon nanospheres and hollow carbon fibers were amorphous materials. The mesoporous carbon nanospheres show good stability in the cyclic voltammograms and their specific capacitance at 10 mV s-1 is 172.1 F/g.

  9. Preparation of ZnO Nanospheres and Their Applications in Dye-Sensitized Solar Cells

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yong-Zhe; WU Li-Hui; LIU Yan-Ping; XIE Er-Qing; YAN De; CHEN Jiang-Tao

    2009-01-01

    ZnO nanospheres are synthesized by a two-step self-assembly method.X-ray diffraction pattern and Raman scattering spectra measurements show that all the samples present a typical wurtzite structure.A regular sphere shape is inspected by field emission scanning electron microscope and transmission electron microscope for the samples.It is shown that the as-synthesized ZnO nanosphere is composed of numbers of primary particles with size of around 10 nm.A possible growth mechanism for the two-step self-assembly ZnO nanosphere is proposed.After applying the ZnO nanospheres to dye-sensitized solar cells (DSSCs),a 117% increase of the overall light to electricity conversion efficiency η is observed compared with that of the ZnO nanoparticles based DSSCs.Associated with the UV-vis results,light scattering is assigned to the great improvement of η.

  10. Synthesis of poly(3-hydroxybutyrate) nanospheres and deposition thereof into porous thin film

    Science.gov (United States)

    Abid, S.; Raza, Z. A.; Rehman, A.

    2016-10-01

    Polymeric nanostructures have gained importance in medical science as drug delivery carriers due to their biocompatibility and biodegradability. Polyhydroxybutyrate (PHB) is one of the natural biodegradable polymers used to deliver drugs in the form of nano/microcapsules. In this study, solvent evaporation method has been used for the synthesis of PHB nanospheres using poly(vinyl) alcohol (PVA) both as emulsifier and stabilizer. The produced PHB nanospheres were analyzed using dynamic light scattering and scanning electron microscopy. The size of nanospheres decreased whereas the zeta potential increased on increasing the concentration of emulsifier. The PHB nanospheres were then deposited into porous thin film on a glass surface and characterized against bulk PHB film by using atomic force microscopy, contact angle measurement and x-ray diffraction.

  11. Fabricating ordered 2-D nano-structured arrays using nanosphere lithography.

    Science.gov (United States)

    Zhang, Chenlong; Cvetanovic, Sandra; Pearce, Joshua M

    2017-01-01

    Recent advances in the use of plasmonic metamaterials to improve absorption of light in thin-film solar photovoltaic devices has created a demand for a scalable method of patterning large areas with metal nanostructures deposited in an ordered array. This article describes two methods of fabricating ordered 2D nanosphere colloidal films: spin coating and interface coating. The two methods are compared and parameter optimization discussed. The study reveals that: •For smaller nanosphere sizes, spin coating is more favorable, while for larger nanospheres, the angled interface coating provides more coverage and uniformity.•A surfactant-free approach for interface coating is developed to fabricate zero-contamination colloidal films.•Each of the methods reaches an overall coverage of more than 90% and can be used for nanosphere lithography to form plasmonic metamaterials.

  12. Fluorescent QDs-polystyrene composite nanospheres for highly efficient and rapid protein antigen detection

    Science.gov (United States)

    Zhou, Changhua; Mao, Mao; Yuan, Hang; Shen, Huaibin; Wu, Feng; Ma, Lan; Li, Lin Song

    2013-09-01

    In this paper, high-quality carboxyl-functionalized fluorescent (red, green, and blue emitting) nanospheres (46-103 nm) consisting of hydrophobic quantum dots (QDs) and polystyrene were prepared by a miniemulsion polymerization approach. This miniemulsion polymerization approach induced a homogeneous distribution and high aqueous-phase transport efficiency of fluorescent QDs in composite nanospheres, which proved the success of our encoding QDs strategy. The obtained fluorescent nanospheres exhibited high stability in aqueous solution under a wide range of pH, different salt concentrations, PBS buffer, and thermal treatment at 80 °C. Based on the red emitting composite nanosphere, we performed fluorescent lateral flow immunoassay (LFIA) strips for high-sensitivity and rapid alpha-fetal protein detection. The detection limit reached 0.1 ng/mL, which was 200 times higher than commercial colloidal gold-labeled LFIA strips, and it reached similar detection level in enzyme-linked immunosorbent assay kit.

  13. Controlled synthesis and magnetic properties of monodispersed ceria nanoparticles

    Directory of Open Access Journals (Sweden)

    Sumeet Kumar

    2015-02-01

    Full Text Available In the present study, monodispersed CeO2 nanoparticles (NPs of size 8.5 ± 1.0, 11.4 ± 1.0 and 15.4 ± 1.0 nm were synthesized using the sol-gel method. Size-dependent structural, optical and magnetic properties of as-prepared samples were investigated by X-ray diffraction (XRD, field emission scanning electron microscope (FE-SEM, high resolution transmission electron microscopy (HR-TEM, ultra-violet visible (UV-VIS spectroscopy, Raman spectroscopy and vibrating sample magnetometer (VSM measurements. The value of optical band gap is calculated for each particle size. The decrease in the value of optical band gap with increase of particle size may be attributed to the quantum confinement, which causes to produce localized states created by the oxygen vacancies due to the conversion of Ce4+ into Ce3+ at higher calcination temperature. The Raman spectra showed a peak at ∼461 cm-1 for the particle size 8.5 nm, which is attributed to the 1LO phonon mode. The shift in the Raman peak could be due to lattice strain developed due to variation in particle size. Weak ferromagnetism at room temperature is observed for each particle size. The values of saturation magnetization (Ms, coercivity (Hc and retentivity (Mr are increased with increase of particle size. The increase of Ms and Mr for larger particle size may be explained by increase of density of oxygen vacancies at higher calcination temperature. The latter causes high concentrations of Ce3+ ions activate more coupling between the individual magnetic moments of the Ce ions, leading to an increase of Ms value with the particle size. Moreover, the oxygen vacancies may also produce magnetic moment by polarizing spins of f electrons of cerium (Ce ions located around oxygen vacancies, which causes ferromagnetism in pure CeO2 samples.

  14. Controlled synthesis and magnetic properties of monodispersed ceria nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Sumeet; Ojha, Animesh K. [Department of Physics, Motilal Nehru National Institute of Technology, Allahabad-211004 (India); Srivastava, Manish, E-mail: 84.srivastava@gmail.com, E-mail: manish-mani84@rediffmail.com [Department of Physics and Astrophysics, University of Delhi, Delhi-110007 (India); Singh, Jay [Department of Applied Chemistry and Polymer Technology, Delhi Technological University, Shahbad Daulatpur, Main Bawana Road, Delhi 110042 (India); Layek, Samar [Department of Physics, Indian Institute of Technology, Kanpur 208016 (India); Yashpal, Madhu [Electron Microscope Facility, Department of Anatomy Institute of Medical Sciences, Banaras Hindu University, Varanasi 221005 (India); Materny, Arnulf [Center for Functional Materials and Nanomolecular Science, Jacobs University Bremen, Campus Ring, 28759 Bremen (Germany)

    2015-02-15

    In the present study, monodispersed CeO{sub 2} nanoparticles (NPs) of size 8.5 ± 1.0, 11.4 ± 1.0 and 15.4 ± 1.0 nm were synthesized using the sol-gel method. Size-dependent structural, optical and magnetic properties of as-prepared samples were investigated by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), high resolution transmission electron microscopy (HR-TEM), ultra-violet visible (UV-VIS) spectroscopy, Raman spectroscopy and vibrating sample magnetometer (VSM) measurements. The value of optical band gap is calculated for each particle size. The decrease in the value of optical band gap with increase of particle size may be attributed to the quantum confinement, which causes to produce localized states created by the oxygen vacancies due to the conversion of Ce{sup 4+} into Ce{sup 3+} at higher calcination temperature. The Raman spectra showed a peak at ∼461 cm{sup -1} for the particle size 8.5 nm, which is attributed to the 1LO phonon mode. The shift in the Raman peak could be due to lattice strain developed due to variation in particle size. Weak ferromagnetism at room temperature is observed for each particle size. The values of saturation magnetization (Ms), coercivity (Hc) and retentivity (Mr) are increased with increase of particle size. The increase of Ms and Mr for larger particle size may be explained by increase of density of oxygen vacancies at higher calcination temperature. The latter causes high concentrations of Ce{sup 3+} ions activate more coupling between the individual magnetic moments of the Ce ions, leading to an increase of Ms value with the particle size. Moreover, the oxygen vacancies may also produce magnetic moment by polarizing spins of f electrons of cerium (Ce) ions located around oxygen vacancies, which causes ferromagnetism in pure CeO{sub 2} samples.

  15. Optical nanosphere sensor based on shell-by-shell fabrication for removal of toxic metals from human blood.

    Science.gov (United States)

    El-Safty, S A; Abdellatef, S; Ismael, M; Shahat, A

    2013-06-01

    Because toxic heavy metals tend to bioaccumulate, they represent a substantial human health hazard. Various methods are used to identify and quantify toxic metals in biological tissues and environment fluids, but a simple, rapid, and inexpensive system has yet to be developed. To reduce the necessity for instrument-dependent analysis, we developed a single, pH-dependent, nanosphere (NS) sensor for naked-eye detection and removal of toxic metal ions from drinking water and physiological systems (i.e., blood). The design platform for the optical NS sensor is composed of double mesoporous core-shell silica NSs fabricated by one-pot, template-guided synthesis with anionic surfactant. The dense shell-by-shell NS construction generated a unique hierarchical NS sensor with a hollow cage interior to enable accessibility for continuous monitoring of several different toxic metal ions and efficient multi-ion sensing and removal capabilities with respect to reversibility, longevity, selectivity, and signal stability. Here, we examined the application of the NS sensor for the removal of toxic metals (e.g., lead ions from a physiological system, such as human blood). The findings show that this sensor design has potential for the rapid screening of blood lead levels so that the effects of lead toxicity can be avoided.

  16. Utilization of microfluidic V-junction device to prepare surface itraconazole adsorbed nanospheres.

    OpenAIRE

    Kucuk, I.; Ahmad, Z.; Edirisinghe, M.; Orlu-Gul, M.

    2014-01-01

    Itraconazole is widely used as an anti-fungal drug to treat infections. However its poor aqueous solubility results in low bioavailability. The aim of the present study was to improve the drug release profile by preparing surface itraconazole adsorbed polymethylsilsesquioxane (PMSQ) nanospheres using a V-junction microfluidic (VJM) device. In order to generate nanospheres with rough surface, the process flow rate of Perfluorohexane (PFH) was set between 50 and 300 μl min(-1) while the flow ra...

  17. Simulations of solar cell absorption enhancement using resonant modes of a nanosphere array

    OpenAIRE

    2012-01-01

    We propose an approach for enhancing the absorption of thin-film amorphous silicon solar cells using periodic arrangements of resonant dielectric nanospheres deposited as a continuous film on top of a thin planar cell. We numerically demonstrate this enhancement using three dimensional (3D) full field, finite difference time domain simulations and 3D finite element device physics simulations of a nanosphere array above a thin-film amorphous silicon solar cell structure featuring back reflecto...

  18. Size-controllable polypyrrole nanospheres synthesized in the presence of phosphorylated chitosan and their size effect in different applications

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jing; Cao, Yi; Lu, Yun, E-mail: yunlu@nju.edu.cn [Nanjing University, Department of Polymer Science and Engineering, State Key Laboratory of Coordination Chemistry, Key Laboratory of High Performance Polymer Materials and Technology of Ministry of Education, School of Chemistry and Chemical Engineering (China)

    2015-05-15

    The size-controllable polypyrrole (PPy) nanospheres are successfully synthesized by oxidative polymerization of pyrrole using N-methylene phosphonic chitosan (NMPC) as a structure-directing agent. By simply changing the amount of NMPC, the size of the PPy nanospheres can be adjusted from 190 to 50 nm in diameter. The spectrometric results suggest that the electrostatic interactions of phosphate groups in NMPC molecule with pyrrole ring might be a driving force for formation of the uniform and size-controllable PPy nanospheres. The PPy nanospheres with the diameter of 100 nm exhibit the largest capacity and a good cycling stability as electrode materials of supercapacitors. The as-prepared PPy nanospheres also can be combined with carbon dots to form composite nanospheres presenting enhanced fluorescence intensity, which show potential application in fluorescence detection.

  19. Optical properties of local surface plasmon resonance in Ag/ITO sliced nanosphere by the discrete dipole approximation

    Energy Technology Data Exchange (ETDEWEB)

    Haiwei, Mu; Jingwei, Lv; Zhaoting, Liu; Lin, Yang; Qiang, Liu; Chao, Liu [Northeast Petroleum University, School of Electronics Science, Daqing (China); Shijie, Zheng [Harbin Institute of Technology, School of Civil Engineering, Harbin (China); Tao, Sun [Agency for Science, Technology and Research (A-STAR), Institute of Microelectronics, Singapore (Singapore)

    2016-04-15

    Optical properties of localized surface plasmon resonances (LSPR) of Ag/ITO sliced nanosphere have been studied using discrete dipole approximation and plasmon hybridization theory. It is found that different morphologies of sliced nanosphere can induce distinctive features in the extinction spectra. In the meanwhile, gap distances and refractive index of the surrounding medium could modulate the plasmon hybridization and the LSPR shifting. At large separation, the shift of LSPR peaks for the nanosphere sliced in halves consisting of ITO and Ag is small and insensitive to the gap distance in the weak coupling, whereas smaller separation exhibits a distinct red shift. Additionally, multiple resonance peaks are excited for the nanosphere sliced in quarters consisting of ITO and Ag. In this situation, electric field is mainly distributed in the gap region of sliced nanosphere and the central point. These results indicate that different morphologies of sliced nanosphere could create abundant tunable LSPR modes, which provides potential for multiplex optical sensing. (orig.)

  20. Continuous Fluorescence Imaging of Intracellular Calcium by Use of Ion-Selective Nanospheres with Adjustable Spectra.

    Science.gov (United States)

    Yang, Chenye; Qin, Yu; Jiang, Dechen; Chen, Hong-Yuan

    2016-08-10

    Continuous fluorescence imaging of intracellular ions in various spectral ranges is important for biological studies. In this paper, fluorescent calcium-selective nanospheres, including calix[4]arene-functionalized bodipy (CBDP) or 9-(diethylamino)-5-[(2-octyldecyl)imino]benzo[a]phenoxazine (ETH 5350) as the chromoionophore, were prepared to demonstrate intracellular calcium imaging in visible or near-IR regions, respectively. The fluorescence of the nanospheres was controlled by the chromoionophore, and thus the spectral range for detection was adjustable by choosing the proper chromoionophore. The response time of the nanospheres to calcium was typically 1 s, which allowed accurate measurement of intracellular calcium. These nanospheres were loaded into cells through free endocytosis and exhibited fluorescence for 24 h, and their intensity was correlated with the elevation of intracellular calcium upon stimulation. The successful demonstration of calcium imaging by use of ion-selective nanospheres within two spectral ranges in 24 h supported that these nanospheres could be applied for continuous imaging of intracellular ions with adjustable spectra.

  1. Synthesis and structure determination of uranyl peroxide nanospheres in the presence of organic structure directing agents

    Science.gov (United States)

    Forbes, T. Z.; Burns, P. C.

    2007-12-01

    Recently, actinyl peroxide nanoclusters containing 20, 24, 28, or 32 actinyl polyhedra have been synthesized and their structures identified with single crystal X-ray diffraction [1]. Most nanomaterials are composed of main group elements or transition metals, therefore, these actinyl nanospheres may display vastly different chemical and physical properties due to the presence of filled f-orbitals. A major goal of our research group is to create novel actinyl materials, focusing on nano- and mesoporous materials. The original nanosphere syntheses were limited to inorganic crystallization agents, such as monovalent cations. Over the last decade, the use of organic compounds and surfactants have received increased attention as structure-directing agents for the generation of novel inorganic materials. Using structure-directing organic amines we have successfully synthesized and determined the structures of uranyl nanospheres containing 40 and 50 uranyl polyhedra. The topology of the skeletal U-50 nanosphere is identical to the C50Cl10 fullerene [2]. The topographical relationship between the actinyl nanospheres and fullerene or fullerene-like material may provide additional insight into stable configurations for lower fullerenes. [1] Burns et al., Actinyl peroxide nanospheres. Angewandte Chemie, International Edition, 2005. 44(14): p. 2135. [2] Xie et al., Capturing the Labile Fullerene[50] as C50Cl10. Science, (2004) 305(5671): p. 699.

  2. Estrone specific molecularly imprinted polymeric nanospheres: synthesis, characterization and applications for electrochemical sensor development.

    Science.gov (United States)

    Congur, Gulsah; Senay, Hilal; Turkcan, Ceren; Canavar, Ece; Erdem, Arzum; Akgol, Sinan

    2013-06-28

    The aim of this study is (i) to prepare estrone-imprinted nanospheres (nano-EST-MIPs) and (ii) to integrate them into the electrochemical sensor as a recognition layer. N-methacryloyl-(l)-phenylalanine (MAPA) was chosen as the complexing monomer. Firstly, estrone (EST) was complexed with MAPA and the EST-imprinted poly(2-hyroxyethylmethacrylate-co-N-methacryloyl-(l)-phenylalanine) [EST-imprinted poly(HEMA-MAPA)] nanospheres were synthesized by surfactant- free emulsion polymerization method. The specific surface area of the EST-imprinted poly(HEMA-MAPA) nanospheres was found to be 1275 m2/g with a size of 163.2 nm in diameter. According to the elemental analysis results, the nanospheres contained 95.3 mmole MAPA/g nanosphere. The application of EST specific MIP nanospheres for the development of an electrochemical biosensor was introduced for the first time in our study by using electrochemical impedance spectroscopy (EIS) technique. This nano-MIP based sensor presented a great specificity and selectivity for EST.

  3. Direct fabrication of hybrid nanofibres composed of SiO2-PMMA nanospheres via electrospinning.

    Science.gov (United States)

    Zhang, Ran; Shang, Tinghua; Yang, Guang; Jia, Xiaolong; Cai, Qing; Yang, Xiaoping

    2016-08-01

    The direct fabrication of hybrid nanofibres composed of poly(methyl methacrylate)-grafted SiO2 (SiO2-PMMA) nanospheres via electrospinning was investigated in detail. SiO2-PMMA nanospheres were successfully prepared, with the SiO2 nanospheres synthesized via the Stober method, followed by in situ surface-initiated atom transfer radical polymerization of methyl methacrylate (MMA). Electrospinning was carried out with N,N-dimethylformamide (DMF) as the solvent to disperse SiO2-PMMA nanospheres. The size of the SiO2 core, the molecular weight of the PMMA shell and the concentration of the SiO2-PMMA/DMF solution all had substantial effects on the morphology and structure of electrospun nanofibres composed of SiO2-PMMA nanospheres. When these determining factors were well-tailored, it was found that one-dimensional necklace-like nanofibres were obtained, with SiO2-PMMA nanospheres aligned one by one along the fibre. The successful fabrication of nanofibres by directly electrospinning the SiO2-PMMA/DMF solution verified that polymer-grafted particles possess polymer-like characteristics, which endowed them with the ability to be processed into desirable shapes and structures.

  4. Efficient removal and highly selective adsorption of Hg2+ by polydopamine nanospheres with total recycle capacity

    Science.gov (United States)

    Zhang, Xiulan; Jia, Xin; Zhang, Guoxiang; Hu, Jiamei; Sheng, Wenbo; Ma, Zhiyuan; Lu, Jianjiang; Liu, Zhiyong

    2014-09-01

    This study reported a new method for efficient removal of Hg2+ from contaminated water using highly selective adsorptive polydopamine (PDA) nanospheres, which were uniform and had a small diameter (150-200 nm). The adsorption isotherms, kinetics, thermodynamics were investigated. Also, the effects of ionic strength, co-existing ions on removing ability of PDA nanospheres for Hg2+ were studied. Adsorption of Hg2+ was very fast and efficient as adsorption equilibrium was completed within 4 h and the maximum adsorption capacities were 1861.72 mg/g, 2037.22 mg/g, and 2076.81 mg/g at 298 K, 313 K, and 328 K respectively, increasing with increasing of temperature. The PDA nanospheres exhibited highly selective adsorption of Hg2+ and had a total desorption capacity of 100% in hydrochloric acid solution, pH 1. The results showed that the structure of PDA nanospheres remained almost unchanged after recycling five times. Furthermore, X-ray photoelectron spectroscopy (XPS) was employed to determine the elements of PDA nanospheres before and after Hg2+ adsorption. Considering their efficient and highly Hg2+ selective adsorption, total recycle capacity, and high stability, PDA nanospheres will be feasible in a number of practical applications.

  5. Nanoparticle and nanosphere mask for etching of ITO nanostructures and their reflection properties

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Cigang; Deng, Ligang; Holder, Adam; Bailey, Louise R.; Proudfoot, Gary; Thomas, Owain; Gunn, Robert; Cooke, Mike [Oxford Instruments Plasma Technology, Bristol (United Kingdom); Leendertz, Caspar [Helmholtz-Zentrum Berlin fuer Materialien und Energie, Institut fuer Silizium Photovoltaik, Berlin (Germany); Bergmann, Joachim [Leibniz Institute of Photonic Technology, Jena (Germany)

    2015-01-01

    Au nanoparticles and polystyrene nanospheres were used as mask for plasma etching of indium tin oxide (ITO) layer. By reactive ion etching (RIE) processes, the morphology of polystyrene nanospheres can be tuned through chemical or physical etching, and Au nanoparticle mask can result in ITO nanostructures with larger aspect ratio than nanosphere mask. During inductively coupled plasma (ICP) processes, Au nanoparticle mask was not affected by the thermal effect of plasma, whereas temperature of the substrate was essential to protect nanospheres from the damaging effect of plasma. Physical bombardment in the plasma can also modify the nanospheres. It was observed that under the same process conditions, the ratio of CH{sub 4} and H{sub 2} in the process gas can affect the etching rate of ITO without completely etching the nanospheres. The morphology of ITO nanostructures also depends on process conditions. The resulting ITO nanostructures show lower reflection in a spectral range of 400-1000 nm than c-Si and conventional antireflection layer of SiN{sub x} film. ITO nanostructures obtained after etching (scale bar = 200 nm). (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. Dry-powder form of chitosan nanospheres containing influenza virus and adjuvants for nasal immunization.

    Science.gov (United States)

    Dehghan, S; Tavassoti Kheiri, M; Tabatabaiean, M; Darzi, S; Tafaghodi, M

    2013-08-01

    The objective of this study was to develop and statistically optimize chitosan nanospheres. For this purpose chitosan powder was turned into nanospheres using tripolyphosphate as a crosslinker and through ionic gelation. D-optimal response surface design was applied to optimize the nanospheres. Their size and polydispersity index (PDI) were measured as the dependant variables. Then the inactivated influenza virus and/or CpG ODN or Quillaja saponin (QS) were incorporated into the chitosan nanospheres. The release profiles of the antigen and both adjuvants were obtained. The toxicity of the formulations was tested by XTT using Calu 6 cell lines. The size distribution and PDI of plain chitosan nanospheres was 581.1 ± 32.6 and 0.478 ± 0.04. After 4 h the release of antigen, QS and CpG from the chitosan matrix were 33, 36 and 62%, respectively. The inactivated virus remained intact during preparation, as revealed by the SDS-PAGE method. Differential scanning calorimetry and Fourier Transform Infrared Spectroscopy indicated no serious structural changes in the chitosan carrier in the presence of either the antigen or the immunoadjuvants. Although the antigen loaded into chitosan nanospheres showed slight cytotoxicity on lung-cancer cells, co-encapsulation of the adjuvant (especially CpG) lowered this effect. The results demonstrated that chitosan as a carrier and immunostimulator, along with CpG or QS adjuvants, creates a potential influenza vaccine delivery system which can be administered nasally.

  7. Synthesis, characterization and X-ray spectral investigation of hollow graphitic carbon nanospheres

    Energy Technology Data Exchange (ETDEWEB)

    Ilkiv, Bogdan [Frantsevich Institute for Problems of Materials Science, 3 Krzhyzhanivsky Str., Kyiv 03680 (Ukraine); Petrovska, Svitlana, E-mail: sw.piotrowska@gmail.com [Frantsevich Institute for Problems of Materials Science, 3 Krzhyzhanivsky Str., Kyiv 03680 (Ukraine); Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, Sendai 980-8577 (Japan); Sergiienko, Ruslan [Physico-Technological Institute of Metals and Alloys NAS of Ukraine, 34/1 Vernadsky Ave., Kyiv 142 03680 (Ukraine); Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, Sendai 980-8577 (Japan); Foya, Oleksandr [Frantsevich Institute for Problems of Materials Science, 3 Krzhyzhanivsky Str., Kyiv 03680 (Ukraine); Ilkiv, Oleksandra [National Technical University of Ukraine “Kyiv Polytechnic Institute”, Engineering-Physical Faculty, 35 Polytekchnichna Str., Kyiv 03056 (Ukraine); Shibata, Etsuro; Nakamura, Takashi [Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, Sendai 980-8577 (Japan); Zaulychnyy, Yaroslav [Frantsevich Institute for Problems of Materials Science, 3 Krzhyzhanivsky Str., Kyiv 03680 (Ukraine); National Technical University of Ukraine “Kyiv Polytechnic Institute”, Engineering-Physical Faculty, 35 Polytekchnichna Str., Kyiv 03056 (Ukraine)

    2014-12-25

    Highlights: • We synthesized hollow graphitic carbon nanospheres. • We investigated the electronic structure of hollow graphitic carbon nanospheres. • Additional mixed π + σ overlapping occurred in the hollow graphitic carbon nanospheres. • Some residual iron atoms form sp hybrid bonds with carbon. - Abstract: Hollow graphitic carbon nanospheres (HGCNSs) obtained by treatment of iron carbide-filled carbon nanocapsules were investigated using the ultra-soft X-ray emission spectroscopy method. Carbon nanocapsules were synthesized by the plasma discharge method in an ultrasonic cavitation field of liquid hexane. It was revealed that additional mixed π + σ-overlapping occurred in the hollow graphitic carbon nanospheres as a result of the bending of the graphene sheets. Some iron atoms remained after washing in acid. It was found that in the hollow graphitic carbon nanospheres, sp-hybrid bonds formed between the carbon and residual iron atoms when high-energy 3d + 4s-states overlapped with sp{sup n}-hybrid orbitals (2 < n < 3). Scanning and transmission electron microscopy methods were used to study the spatial morphology and structure of the fabricated HGCNSs. The electronic structures of the HGCNSs were compared with those of reference synthetic graphite powder, carbon onions, and graphene nanosheets.

  8. Kinetics of silica polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Weres, O.; Yee, A.; Tsao, L.

    1980-05-01

    The polymerization of silicic acid in geothermal brine-like aqueous solutions to produce amorphous silica in colloidal form has been studied experimentally and theoretically. A large amount of high quality experimental data has been generated over the temperature rang 23 to 100{sup 0}C. Wide ranges of dissolved silica concentration, pH, and sodium chloride concentration were covered. The catalytic effects of fluoride and the reaction inhibiting effects of aluminum and boron were studied also. Two basic processes have been separately studied: the formation of new colloidal particles by the homogeneous nucleation process and the deposition of dissolved silica on pre-existing colloidal particles. A rigorous theory of the formation of colloidal particles of amorphous silica by homogeneous nucleation was developed. This theory employs the Lothe-Pound formalism, and is embodied in the computer code SILNUC which quantitatively models the homogeneous nucleation and growth of colloidal silica particles in more than enough detail for practical application. The theory and code were extensively used in planning the experimental work and analyzing the data produced. The code is now complete and running in its final form. It is capable of reproducing most of the experimental results to within experimental error. It is also capable of extrapolation to experimentally inaccessible conditions, i.e., high temperatures, rapidly varying temperature and pH, etc.

  9. Biomimetic synthesis of calcium-strontium apatite hollow nanospheres

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    In this work,calcium-strontium apatite (Sr-HA) hollow nanospheres were synthesized by a facile biomimetic method.The structure and property of Sr-HA were characterized by FESEM,TEM,HRTEM,XRD and FT-IR spectroscopy.The influences of different ratios of calcium and strontium on the morphologies of the Sr-HA products were investigated.The experimental results revealed that the hollow spherical Sr-HA,with a size of 30-120 nm in diameter,could be synthesized when the molar ratio of Ca/Sr was 1:1.The possible formation mechanism of the hollow Sr-HA was proposed.The drug release experiments indicated that the hollow spherical Sr-HA had the property of sustained release.

  10. Novel synthesis of stable polypyrrole nanospheres using ozone.

    Science.gov (United States)

    Vetter, Christopher A; Suryawanshi, Abhijit; Lamb, Jessica R; Law, Benedict; Gelling, Victoria J

    2011-11-15

    In this study, a novel and exceedingly simple method for the aqueous synthesis of stable, unagglomerated polypyrrole nanospheres was investigated. The method is template- and surfactant-free and uses only pyrrole monomer, water, and ozone. When the monomer concentration, exposure time to ozone, and temperature were varied, it was determined that the temperature was the critical factor controlling the particle size through particle size measurements via dynamic light scattering and transmission electron microscopy (TEM). From the particle size measurements, a particle size distribution with a number-weighted mean diameter of 73 nm and a standard deviation of 18 nm was achieved. The particles were also investigated using ζ-potential measurements, ultraviolet-visible (UV-vis) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, and thermogravimetric analysis in an effort to determine the identity of the nanoparticles as well as the mechanism by which the nanoparticles are formed and stabilized.

  11. Ultrasensitive ELISA using enzyme-loaded nanospherical brushes as labels.

    Science.gov (United States)

    Qu, Zhenyuan; Xu, Hong; Xu, Ping; Chen, Kaimin; Mu, Rong; Fu, Jianping; Gu, Hongchen

    2014-10-01

    Improving the detection sensitivity of enzyme-linked immunosorbent assay (ELISA) is of utmost importance for meeting the demand of early disease diagnosis. Herein we report an ultrasensitive ELISA system using horseradish peroxidase (HRP)-loaded nanospherical poly(acrylic acid) brushes (SPAABs) as labels. HRP was covalently immobilized in SPAABs with high capacity and activity via an efficient "chemical conjugation after electrostatic entrapment" (CCEE) process, thus endowing SPAABs with high amplification capability as labels. The periphery of SPAAB-HRP was further utilized to bind a layer of antibody with high density for efficient capture of analytes owing to the three-dimensional architecture of SPAABs. Using human chorionic gonadotrophin (hCG) as a model analyte, the SPAAB-amplified system drastically boosted the detection limit of ELISA to 0.012 mIU mL(-1), a 267-fold improvement as compared to conventional ELISA systems.

  12. Polymeric Nanoparticles, Nanospheres and Nanocapsules, for Cutaneous Applications

    Directory of Open Access Journals (Sweden)

    Adriana R. Pohlmann

    2007-01-01

    Full Text Available This review presents an overview about pharmaceutical and cosmetic topical products containing polymeric nanoparticles (nanospheres and nanocapsules, reporting the main preparation and characterization methods and the studies of penetration and transport of substances through the skin. The penetration and transport extent of those systems through the skin depends on the ingredients chemical composition, on the encapsulation mechanism influencing the drug release, on the size of nanoparticles and on the viscosity of the formulations. The polymeric nanoparticles are able to modify the activity of drugs, delay and control the drug release, and increase the drug adhesivity or its time of permanence in the skin. Briefly, the nanoparticles can be useful as reservoirs of lipophilic drugs to deliver them in the stratum corneum becoming an important strategy to control their permeation into the skin.

  13. Plasmon-enhanced fluorescence near nonlocal metallic nanospheres

    DEFF Research Database (Denmark)

    Tserkezis, Christos; Stefanou, N.; Wubs, Martijn

    ) of a dipole emitter. Here we explore the importance of hitherto disregarded nonclassical effects in the description of emitter-plasmon hybrids, focusing on the roles of metal nonlocal optical response and size-dependent plasmon damping [1]. Comparison between the common local response approximation (LRA......) and the generalized nonlocal optical response (GNOR) theory [2] shows that a significant decrease in fluorescence enhancement is obtained for emitters close to small metallic nanospheres or thin metallic nanoshells, while the optimum emitter position is also affected. In this respect, our recent work introduces...... the study of emitterplasmon coupling (in the weak-coupling limit) as a sensitive test for the validity of stateof-the-art nonclassical models. For the regime of strong emitter-plasmon coupling, we anticipate an analogously wide importance of a description beyond classical electrodynamics, particularly once...

  14. Optimizing plasmon-enhanced fluorescence with nonlocal metallic nanospheres

    DEFF Research Database (Denmark)

    Tserkezis, Christos; Stefanou, Nikolaos; Wubs, Martijn

    nonlocal corrections, the plasmon blueshift predicted by the hydrodynamic Drude model [1] leads to a small reduction of η. If however the plasmonic mode does not coincide exactly with λem, this blueshift can tune the mode to increase η. Nevertheless, when size-dependent losses are also taken into account......The fluorescence signal η of molecules coupled to plasmonic nanoparticles (NPs) is optimized through extended simulations, taking the metal nonlocal optical response fully into account. Solid Au and Ag nanospheres, as well as SiO2/Au(Ag) core/shell NPs (of total radius R), are engineered...... to maximize the ratio of radiative to nonradiative losses and match the emitter emission wavelength, λem. For a molecule modeled as an electric dipole p, oriented parallel to the incident field E, the optimal emitter-NP distance is then identified within the local response approximation (LRA). Introducing...

  15. Shape-induced separation of nanospheres and aligned nanorods.

    Science.gov (United States)

    Ahmad, I; Zandvliet, H J W; Kooij, E S

    2014-07-15

    We studied the phase separation and spatial arrangement of gold nanorods and nanospheres after evaporative self-assembly from aqueous suspension. Depending on the position relative to the contact line of the drying droplet, spheres and rods separate into various liquid-crystalline phases. Nanorods exhibit a strong preference for side-by-side alignment, giving rise to smectic phases; spheres in solution are forced out of these regions and form close-packed arrays. We discuss this self-separation into nanorod- and sphere-rich phases in terms of various interactions, including electrostatic, van der Waals, and deplection interactions forces. The experimental results are compared to quantitative calculations of the colloidal interaction energies. We also describe and discuss the role of the surfactant on the different crystal facets of the nanorods on the assembly process.

  16. Reproducible Ultrahigh Electromagnetic SERS Enhancement in Nanosphere-Plane Junctions

    CERN Document Server

    Long, Jing; Li, Hongquan; Yang, Tian

    2015-01-01

    Surface enhanced Raman scattering (SERS) in nanoscale hotspots has been placed great hopes upon for identification of minimum chemical traces and in-situ investigation of single molecule structures and dynamics. However, previous work consists of either irreproducible enhancement factors (EF) from random aggregates, or moderate EFs despite better reproducibility. Consequently, systematic study of SERS at the single and few molecules level is still very limited, and the promised applications are far from being realized. Here we report EFs as high as the most intense hotspots in previous work yet achieved in a reproducible and well controlled manner, that is, electromagnetic EFs (EMEF) of 10^9~10 with an error down to 10^+/-0.08 from gold nanospheres on atomically flat gold planes under radially polarized (RP) laser excitation. In addition, our experiment reveals the EF's unexpected nonlinearity under as low as hundreds of nanowatts of laser power.

  17. Quantum dots-hyperbranched polyether hybrid nanospheres towards delivery and real-time detection of nitric oxide

    DEFF Research Database (Denmark)

    Liu, Shuiping; Gu, Tianxun; Fu, Jiajia;

    2014-01-01

    In this work, novel hybrid nanosphere vehicles were synthesized for nitric oxide (NO) donating and real-time detection. The hybrid nanosphere vehicles consist of cadmium selenide quantum dots (CdSe QDs) as NO fluorescent probes, and the modified hyperbranched polyether (mHP)-based diazeniumdiolat...... mechanism. The low cell-toxicity of QDs-mHP-NO nanospheres was verified by means of MTT assay on L929 cells viability. The QDs-mHP-NO nanospheres provide perspectives for designing a new class of biocompatible NO donating and imaging systems....

  18. Effect of Sn loading on the photocatalytic aniline synthesis activity of TiO{sub 2} nanospheres

    Energy Technology Data Exchange (ETDEWEB)

    Mohamed, R.M., E-mail: redama123@yahoo.com [Chemistry Department, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21589 (Saudi Arabia); Nanostructured Material Division Advanced Materials Department, Central Metallurgical R and D Institute, Helwan 11421, Cairo (Egypt); Center of Excellence in Environmental Studies, King Abdulaziz University, P.O. Box 80216, Jeddah 21589 (Saudi Arabia); Aazam, E.S. [Chemistry Department, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21589 (Saudi Arabia)

    2014-05-15

    Highlights: • Sn/TiO{sub 2} nanospheres were used for photocatalytic production of aniline. • Photocatalytic reduction of nitrobenzene was dependent on wt% of Sn. • Catalyst re-use revealed the present photocatalyst remain effective and active after five cycles. - Abstract: TiO{sub 2} nanospheres and Sn/TiO{sub 2} nanospheres were prepared by a hydrothermal method. The prepared samples were characterized by XRD, Pl, UV–Vis, BET, SEM, and TEM. The results reveal that Sn{sup 4+} replaces a small part of the Ti{sup 4+} from the TiO{sub 2} lattice. Doping of Sn increases the surface area of the TiO{sub 2} nanospheres. Doping of Sn leads to a decrease in the band gap of the TiO{sub 2} nanospheres and increases the lifetime of the electron–hole recombination. Doping of Sn into the TiO{sub 2} nanospheres enhances the photocatalytic activity of the TiO{sub 2} nanospheres for the reduction of nitrobenzene to aniline under visible light. The optimal Sn loading was found to be 4 wt%. The photocatalytic activity of the 4 wt% Sn/TiO{sub 2} nanospheres is approximately 80 times greater than the photocatalytic activity of the TiO{sub 2} nanospheres.

  19. PVP assisted solvothermal synthesis of uniform Cu{sub 2}FeSnS{sub 4} nanospheres

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Meng; Li, Chao; Zhang, Binlei; Huang, Jian, E-mail: jianhuang@shu.edu.cn; Wang, Linjun; Shen, Yue, E-mail: yueshen@staff.shu.edu.cn

    2015-02-15

    Graphical abstract: TEM image of CFTS nanospheres synthesized with 0.2 g PVP and 40 ml EG at 180 °C for 24 h. - Highlights: • Cu{sub 2}FeSnS{sub 4} nanospheres were synthesized by solvothermal method. • PVP improved dispersibility and morphology of Cu{sub 2}FeSnS{sub 4} nanospheres greatly. • Optoelectronic properties of Cu{sub 2}FeSnS{sub 4} were enhanced after annealing process. - Abstract: Well dispersed Cu{sub 2}FeSnS{sub 4} (CFTS) nanospheres were firstly synthesized by a facile solvothermal method using ethylene glycol (EG) as the reaction medium and PVP as the surface ligand. The structural, morphological, chemical composition and optical properties of as-synthesized CFTS nanospheres were characterized using X-ray diffraction (XRD), Raman spectroscopy, energy dispersive X-ray spectrometry (EDS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV-Vis spectrophotometry. The average particle sizes of the nanospheres were in the range of 0.4-0.6 μm. Time dependent SEM, XRD and EDS were measured to investigate the mechanism of the morphological evolution of CFTS nanospheres. The band-gap of the as-synthesized CFTS nanospheres was estimated to be about 1.33 eV from the UV-Vis absorption spectra. Photoresponses of CFTS nanospheres were confirmed by IV measurements under dark and light illumination. All these indicated their potential solar cell applications.

  20. Silica encapsulation of fluorescent nanodiamonds for colloidal stability and facile surface functionalization.

    Science.gov (United States)

    Bumb, Ambika; Sarkar, Susanta K; Billington, Neil; Brechbiel, Martin W; Neuman, Keir C

    2013-05-29

    Fluorescent nanodiamonds (FNDs) emit in the near-IR and do not photobleach or photoblink. These properties make FNDs better suited for numerous imaging applications compared with commonly used fluorescence agents such as organic dyes and quantum dots. However, nanodiamonds do not form stable suspensions in aqueous buffer, are prone to aggregation, and are difficult to functionalize. Here we present a method for encapsulating nanodiamonds with silica using an innovative liposome-based encapsulation process that renders the particle surface biocompatible, stable, and readily functionalized through routine linking chemistries. Furthermore, the method selects for a desired particle size and produces a monodisperse agent. We attached biotin to the silica-coated FNDs and tracked the three-dimensional motion of a biotinylated FND tethered by a single DNA molecule with high spatial and temporal resolution.

  1. Fractals of Silica Aggregates

    Institute of Scientific and Technical Information of China (English)

    ZhinhongLi; DongWu; Yuhansun; JunWang; YiLiu; BaozhongDong; Zhinhong

    2001-01-01

    Silica aggregates were prepared by base-catalyzed hydrolysis and condensation of alkoxides in alcohol.Polyethylene glycol(PEG) was used as organic modifier.The sols were characterized using Small Angle X-ray Scattering (SAXS) with synchrotron radiation as X-ray source.The structure evolution during the sol-gel process was determined and described in terms of the fractal geometry.As-produced silica aggregates were found to be mass fractals.The fractl dimensions spanned the regime 2.1-2.6 corresponding to more branched and compact structures.Both RLCA and Eden models dominated the kinetic growth under base-catalyzed condition.

  2. Solvothermal synthesis and characterization of monodisperse superparamagnetic iron oxide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Li, Shichuan; Zhang, Tonglai; Tang, Runze; Qiu, Hao [State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081 (China); Wang, Caiqin [Shandong Special Industry Group Co., Ltd, Shandong 255201 (China); Zhou, Zunning [State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081 (China)

    2015-04-01

    A series of magnetic iron oxide nanoparticle clusters with different structure guide agents were synthesized by a modified solvothermal method and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), thermogravimetric analyses (TG), a vibrating sample magnetometer (VSM) and Fourier transform infrared spectroscopy (FTIR). It is found that the superparamagnetic nanoparticles guided by NaCit (sodium citrate) have high saturation magnetization (M{sub s}) of 69.641 emu/g and low retentivity (M{sub r}) of 0.8 emu/g. Guiding to form superparamagnetic clusters with size range of 80–110 nm, the adherent small-molecule citrate groups on the surface prevent the prefabricated ferrite crystals growing further. In contrast, the primary small crystal guided and stabilized by the PVP long-chain molecules assemble freely to larger ones and stop growing in size range of 100–150 nm, which has saturation magnetization (M{sub s}) of 97.979 emu/g and retentivity (M{sub r}) of 46.323 emu/g. The relevant formation mechanisms of the two types of samples are proposed at the end. The superparamagnetic ferrite clusters guided by sodium citrate are expected to be used for movement controlling of passive interference particles to avoid aggregation and the sample guided by PVP will be a candidate of nanometer wave absorbing material. - Highlights: • A facile synthesis of two kinds of monodisperse iron oxide nano-particle clusters was performed via a modified one-step solvothermal method in this work. • The NaCit and PVP as different guiding agents are used to control the formation and aggregation of nano-crystals during reacting and the ripening processes. • The superparamagnetic NaCit–Fe{sub 3}O{sub 4} samples have high saturation magnetization (M{sub s}) of 69.641 emu/g and low retentivity (M{sub r}) of 0.8 emu/g. • The relevant formation mechanisms of the two types of samples are proposed.

  3. Silica reinforced triblock copolymer gels

    DEFF Research Database (Denmark)

    Theunissen, E.; Overbergh, N.; Reynaers, H.

    2004-01-01

    The effect of silica and polymer coated silica particles as reinforcing agents on the structural and mechanical properties of polystyrene-poly(ethylene/butylene)-polystyrene (PS-PEB-PS) triblock gel has been investigated. Different types of chemically modified silica have been compared in order...... a viscoclastic rubber to a plastic fluid and from a plastic fluid to a viscoelastic liquid are shifted to more elevated temperatures when silica is added to the triblock copolymer gel. (C) 2004 Elsevier Ltd. All rights reserved....

  4. Monodisperse, submicrometer droplets via condensation of microfluidic-generated gas bubbles.

    Science.gov (United States)

    Seo, Minseok; Matsuura, Naomi

    2012-09-10

    Microfluidics (MFs) can produce monodisperse droplets with precise size control. However, the synthesis of monodisperse droplets much smaller than the minimum feature size of the microfluidic device (MFD) remains challenging, thus limiting the production of submicrometer droplets. To overcome the minimum micrometer-scale droplet sizes that can be generated using typical MFDs, the droplet material is heated above its boiling point (bp), and then MFs is used to produce monodisperse micrometer-scale bubbles (MBs) that are easily formed in the size regime where standard MFDs have excellent size control. After MBs are formed, they are cooled, condensing into dramatically smaller droplets that are beyond the size limit achievable using the original MFD, with a size decrease corresponding to the density difference between the gas and liquid phases of the droplet material. Herein, it is shown experimentally that monodisperse, submicrometer droplets of predictable sizes can be condensed from a monodisperse population of MBs as generated by MFs. Using perfluoropentane (PFP) as a representative solvent due to its low bp (29.2 °C), it is demonstrated that monodisperse PFP MBs can be produced at MFD temperatures >3.6 °C above the bp of PFP over a wide range of sizes (i.e., diameters from 2 to 200 μm). Independent of initial size, the generated MBs shrink rapidly in size from about 3 to 0 °C above the bp of PFP, corresponding to a phase change from gas to liquid, after which they shrink more slowly to form fully condensed droplets with diameters 5.0 ± 0.1 times smaller than the initial size of the MBs, even in the submicrometer size regime. This new method is versatile and flexible, and may be applied to any type of low-bp solvent for the manufacture of different submicrometer droplets for which precisely controlled dimensions are required.

  5. Shape-dependent surface-enhanced Raman scattering in gold-Raman probe-silica sandwiched nanoparticles for biocompatible applications.

    Science.gov (United States)

    Li, Ming; Cushing, Scott K; Zhang, Jianming; Lankford, Jessica; Aguilar, Zoraida P; Ma, Dongling; Wu, Nianqiang

    2012-03-23

    To meet the requirement of Raman probes (labels) for biocompatible applications, a synthetic approach has been developed to sandwich the Raman-probe (malachite green isothiocyanate, MGITC) molecules between the gold core and the silica shell in gold-SiO₂ composite nanoparticles. The gold-MGITC-SiO₂ sandwiched structure not only prevents the Raman probe from leaking out but also improves the solubility of the nanoparticles in organic solvents and in aqueous solutions even with high ionic strength. To amplify the Raman signal, three types of core, gold nanospheres, nanorods and nanostars, have been chosen as the substrates of the Raman probe. The effect of the core shape on the surface-enhanced Raman scattering (SERS) has been investigated. The colloidal nanostars showed the highest SERS enhancement factor while the nanospheres possessed the lowest SERS activity under excitation with 532 and 785 nm lasers. Three-dimensional finite-difference time domain (FDTD) simulation showed significant differences in the local electromagnetic field distributions surrounding the nanospheres, nanorods, and nanostars, which were induced by the localized surface plasmon resonance (LSPR). The electromagnetic field was enhanced remarkably around the two ends of the nanorods and around the sharp tips of the nanostars. This local electromagnetic enhancement made the dominant contribution to the SERS enhancement. Both the experiments and the simulation revealed the order nanostars > nanorods > nanospheres in terms of the enhancement factor. Finally, the biological application of the nanostar-MGITC-SiO₂ nanoparticles has been demonstrated in the monitoring of DNA hybridization. In short, the gold–MGITC-SiO₂ sandwiched nanoparticles can be used as a Raman probe that features high sensitivity, good water solubility and stability, low-background fluorescence, and the absence of photobleaching for future biological applications.

  6. Self-assembly and graft polymerization route to Monodispersed Fe3O4@SiO2--polyaniline core-shell composite nanoparticles: physical properties.

    Science.gov (United States)

    Reddy, Kakarla Raghava; Lee, Kwang-Pill; Kim, Ju Young; Lee, Youngil

    2008-11-01

    This study describes the synthesis of monodispersed core-shell composites of silica-modified magnetic nanoparticles and conducting polyaniline by self-assembly and graft polymerization. Magnetic ferrite nanoparticles (Fe3O4) were prepared by coprecipitation of Fe+2 and Fe+3 ions in alkaline solution, and then silananized. The silanation of magnetic particles (Fe3O4@SiO2) was carried out using 3-bromopropyltrichlorosilane (BPTS) as the coupling agent. FT-IR spectra indicated the presence of Fe--O--Si chemical bonds in Fe3O4@SiO2. Core-shell type nanocomposites (Fe3O4@SiO2/PANI) were prepared by grafting polyaniline (PANI) on the surface of silanized magnetic particles through surface initiated in-situ chemical oxidative graft polymerization. The nanocomposites were characterized by high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), Fourier transform infrared (FTIR) spectra, UV-visible spectroscopy, photoluminescence (PL) spectra, electrical conductivity and magnetic characteristics. HRTEM images of the nanocomposites revealed that the silica-modified magnetic particles made up the core while PANI made up the shell. The XPS spectrum revealed the presence of silica in the composites, and the XRD results showed that the composites were more crystalline than pure PANI. PL spectra show that composites exhibit photoluminescent property. Conductivity of the composites (6.2 to 9.4 x 10(-2) S/cm) was higher than that of pristine PANI (3.7 x 10(-3) S/cm). The nanocomposites exhibited superparamagnetism. Formation mechanism of the core-shell structured nanocomposites and the effect of modified magnetic nanoparticles on the electro-magnetic properties of the Fe3O4@SiO2/PANI nanocomposites are also investigated. This method provides a new strategy for the generation of multi-functional nanocomposites that composed of other conducting polymers and metal nanoparticles.

  7. Thin supported silica membranes

    NARCIS (Netherlands)

    Zivkovic, Tijana

    2007-01-01

    This thesis discusses several transport-related aspects relevant for the application of thin supported silica membranes for gas separation and nanofiltration. The influence of support geometry on overall membrane performance is investigated. Planar (i.e., flat plate), tubular, and multichannel suppo

  8. Controllable fabrication of 2D colloidal-crystal films with polystyrene nanospheres of various diameters by spin-coating

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jian; Dong, Peitao [College of Mechatronics Engineering and Automation, National University of Defense Technology, Changsha, Hunan, 410073 (China); State Key Laboratory of Transducer Technology, Chinese Academy of Science (China); Di, Di; Wang, Chaoguang; Wang, Haoxu; Wang, Junfeng [College of Mechatronics Engineering and Automation, National University of Defense Technology, Changsha, Hunan, 410073 (China); Wu, Xuezhong, E-mail: xzwu@nudt.edu.cn [College of Mechatronics Engineering and Automation, National University of Defense Technology, Changsha, Hunan, 410073 (China)

    2013-04-01

    Monolayer and bilayer colloidal-crystal films are used as physical mask in nanosphere lithography (NSL). So far, spin-coating experiments have mainly been designed to form nanosphere monolayer with one given size or obtain small areas of polystyrene (PS) nanosphere monolayer which limited the application of these films used as physical masks. The development of NSL required more study focused on the preparation of colloidal-crystal films with large-scale, high ordering degree and nanospheres of different diameters. In this study, PS nanospheres were self-assembled to form monolayer and bilayer colloidal-crystal films by employing spin-coating technology. Based on our experiments, we have built an experiment system of PS nanospheres of certain size ranging from 200 nm to 1300 nm. To give an instance, we have chosen PS nanospheres of four diameters (223 nm, 347 nm, 509 nm, 1300 nm) to fabricate colloidal-crystal films by adjusting the spin speed and acceleration, and we have investigated the relationship between the monolayer coverage areas and spin parameters by designing different spin speed and acceleration for 509 nm nanosphere. Results revealed that monolayer and bilayer films of PS nanospheres with four different diameters were prepared successfully and the single structure where PS nanospheres were in hexagonal close-packed (HCP) order dominated the surface morphologies of both monolayer and bilayer colloidal-crystal films. For 509 nm PS nanosphere, as the spin speed and acceleration increasing, the monolayer coverage areas increase firstly then decrease and at spin speed 1750 rpm and acceleration 600 rpm/s, the areas reaches the biggest.

  9. PREPARATION OF MONODISPERSE CROSSLINKED POLYMER MICROSPHERES HAVING CHLOROMETHYL GROUP BY DISTILLATION-PRECIPITATION POLYMERIZATION

    Institute of Scientific and Technical Information of China (English)

    Shu-Feng Li; Xin-Lin Yang; Wen-Qiang Huang

    2005-01-01

    Monodisperse crosslinked poly(chloromethylstyrene-co-divinylbenzene) (poly(CMSt-co-DVB)) microspheres were prepared by distillation-precipitation copolymerization of chloromethylstyrene (CMSt) and divinylbenzene (DVB) in neat acetonitrile. The polymer particles had clean surfaces due to the absence of any added stabilizer. The size of the particles ranges from 2.59 μm to 3.19 μm and with mono-dispersity around 1.002-1.014. The effects of monomer feed in copolymerization on the microsphere formation were described. The polymer microspheres were characterized by SEM and chlorinity elemental analysis.

  10. Enzyme-encapsulated silica nanoparticle for cancer chemotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Chiu, Yi-Rong; Ho, Wei-Jen; Chao, Jiun-Shuan; Yuan, Chiun-Jye, E-mail: cjyuan@mail.nctu.edu.tw [National Chiao Tung University, Department of Biological Science and Technology, Taiwan (China)

    2012-03-15

    A novel horseradish peroxidase-encapsulated silica nanoparticle (SNP) was generated in this study under relatively mild conditions. The generated enzyme-encapsulated SNP were relatively uniform in size (average 70 {+-} 14.3 nm), monodispersed, and spherical, as characterized by transmission electron microscopy and scanning electron microscopy. The horseradish peroxidase encapsulated in silica nanoparticle exhibits biological properties, such as a pH-dependent activity profile and k{sub m} value, similar to that of free enzymes. Furthermore, enzyme-encapsulated SNP exhibited good operational stability for the repetitive usage with a relative standard deviation of 5.1 % (n = 10) and a high stability for long term storage (>60 days) at 4 Degree-Sign C. The feasibility of using enzyme-encapsulated SNP in prodrug cancer therapy was also demonstrated by its capability to convert the prodrug indole-3-acetic acid into cytotoxic peroxyl radicals and trigger the death of tumor cells. These results indicate that the developed enzyme-encapsulated SNP has potential in the applications of prodrug cancer therapy.

  11. Growth and Dispersion the Silica Particle on the Glass via Modified Stöber Method and Spray Technique

    Directory of Open Access Journals (Sweden)

    Van Thi Thanh Ho*

    2016-06-01

    Full Text Available We presented the fabrication of a novel geometric light trapping structure based on silica particle. This light trapping structure with good morphology was fabricated through modified Stöber method and spray technique. More importantly, the silica particles were dispersed onto glass by using bottom-up or chemical approach involves a common route used to synthesis silica particles from atomic or molecular scale. An optimized synthesis condition is a combination of optimal values of each reaction parameter of Stöber method that could produce homogenous and mono-dispersed silica nanoparticles with uniform size. The diameter of silica particles can be varied from 200, 430, 560, 460 nm by increasing concentrations of ammonia from 2.33 mM to 4.65 mM, 9.31 mM and 13.96 mM, respectively. We found that the silica particle size was well controlled and uniform from ~200 nm to 560 nm by controlling the ammonia concentration. These results open up the possibility to further fabricate geometric light trapping structure with high scattering level (haze and subsequently to increase the short circuit current density (Jsc in the solar cells

  12. Research on the biological activity and doxorubicin release behavior in vitro of mesoporous bioactive SiO2-CaO-P2O5 glass nanospheres

    Science.gov (United States)

    Wang, Xiang; Wang, Gen; Zhang, Ying

    2017-10-01

    Mesoporous bioactive glass (MBG) nanospheres have been synthesized by a facile method of sacrificing template using cetyl trimethyl ammonium bromide (CTAB) as surfactant. The prepared MBG nanospheres possess high specific surface area (632 m2 g-1) as well as uniform size (∼100 nm). In addition, MBG nanospheres exhibited a quick in vitro bioactive response in simulated body fluids (SBF) and excellent bioactivity of inducing hydroxyapatite (HA) forming on the surface of MBG nanospheres. Furthermore, MBG nanospheres can sustain release of doxorubicin (DOX) with a higher encapsulation efficiency (63.6%) and show distinct degradation in PBS by releasing Si and Ca ions. The encapsulation efficiency and DOX release of MBG nanospheres could be controlled by mesoporous structure and local pH environment. The greater surface area and pore volumes of prepared MBG nanospheres are conducive to bioactive response and drug release in vitro. The amino groups in DOX can be easily protonated at acidic medium to become positively charged NH+3, which allow these drug molecules to be desorbed from the surface of MBG nanospheres via electrostatic effect. Therefore, the synthesized MBG nanospheres have a pH-sensitive drug release capability. In addition, the cytotoxicity of MBG nanospheres was assessed using a cell counting kit-8 (CCK-8), and results showed that the synthesized MBG nanospheres had no significant cytotoxicity to MC3T3 cells. These all indicated that as-prepared MBG nanospheres are promising candidates for bone tissue engineering.

  13. A seeded synthetic strategy for uniform polymer and carbon nanospheres with tunable sizes for high performance electrochemical energy storage.

    Science.gov (United States)

    Qian, Jiasheng; Liu, Mingxian; Gan, Lihua; Tripathi, Pranav K; Zhu, Dazhang; Xu, Zijie; Hao, Zhixian; Chen, Longwu; Wright, Dominic S

    2013-04-14

    We established a novel and facile strategy to synthesize uniform polymer and carbon nanospheres, the diameters of which can be precisely programmed between 35-105 and 30-90 nm, respectively, via time-controlled formation of colloidal seeds. The carbon nanospheres show promising prospects in high rate performance electrochemical energy storage.

  14. Magnetic hyaluronic acid nanospheres via aqueous Diels-Alder chemistry to deliver dexamethasone for adipose tissue engineering.

    Science.gov (United States)

    Jia, Yang; Fan, Ming; Chen, Huinan; Miao, Yuting; Xing, Lian; Jiang, Bohong; Cheng, Qifan; Liu, Dongwei; Bao, Weikang; Qian, Bin; Wang, Jionglu; Xing, Xiaodong; Tan, Huaping; Ling, Zhonghua; Chen, Yong

    2015-11-15

    Biopolymer-based nanospheres have great potential in the field of drug delivery and tissue regenerative medicine. In this work, we present a flexible way to conjugate a magnetic hyaluronic acid (HA) nanosphere system that are capable of vectoring delivery of adipogenic factor, e.g. dexamethasone, for adipose tissue engineering. Conjugation of nanospheres was established by aqueous Diels-Alder chemistry between furan and maleimide of HA derivatives. Simultaneously, a furan functionalized dexamethasone peptide, GQPGK, was synthesized and covalently immobilized into the nanospheres. The magnetic HA nanospheres were fabricated by encapsulating super-paramagnetic iron oxide nanoparticles, which exhibited quick magnetic sensitivity. The aqueous Diels-Alder chemistry made nanospheres high binding efficiency of dexamethasone, and the vectoring delivery of dexamethasone could be easily controlled by a external magnetic field. The potential application of the magnetic HA nanospheres on vectoring delivery of adipogenic factor was confirmed by co-culture of human adipose-derived stem cells (ASCs). In vitro cytotoxicity tests demonstrated that incorporation of dexamethasone into magnetic HA nanospheres showed high efficiency to promote ASCs viabilities, in particular under a magnetic field, which suggested a promising future for adipose regeneration applications. Copyright © 2015 Elsevier Inc. All rights reserved.

  15. Hyperbranched polyether hybrid nanospheres with CdSe quantum dots incorporated for selective detection of nitric oxide

    DEFF Research Database (Denmark)

    Liu, Shuiping; Jin, Lanming; Chronakis, Ioannis S.

    2014-01-01

    In this work, hybrid nanosphere vehicles consisting of cadmium selenide quantum dots (CdSe QDs) were synthesized for nitric oxide (NO) donating and real-time detecting. The nanospheres with QDs being encapsulation have spherical outline with dimension of ~127 nm. The fluorescence properties...

  16. Magnetic Nanospheres Encapsulated by Mesoporous Copper Oxide Shell for Selective Isolation of Hemoglobin.

    Science.gov (United States)

    Guo, Zhi-Yong; Zhang, Yue; Zhang, Dan-Dan; Shu, Yang; Chen, Xu-Wei; Wang, Jian-Hua

    2016-11-02

    A novel strategy for the preparation of magnetic nanospheres encapsulated by mesoporous copper oxide shell, shortly termed as Fe3O4@mCuO, is reported via the calcination of Cu(NH3)4(NO3)2 into continuous mesoporous CuO shell onto the surface of Fe3O4 nanoparticles. The magnetic nanospheres are characterized to possess stable core-shell structure with a crystalline mesoporous CuO layer, exhibiting a CuO loading content of 25.2 ± 1.1% along with a favorable magnetic susceptibility. Fe3O4@mCuO nanospheres exhibit favorable selectivity on the adsorption of hemoglobin with a high adsorption capacity of up to 1162.5 mg g(-1). After adsorption, the high magnetic susceptibility allows convenient separation of the nanospheres by an external magnet. The retained hemoglobin could be readily recovered by using 0.5% (m/v) sodium dodecyl sulfate (SDS) as stripping reagent, providing a recovery of 78%. Circular dichroism spectra illustrate virtually no change in the conformation of hemoglobin after the process of adsorption/desorption. Fe3O4@mCuO nanospheres are further applied for the selective isolation of hemoglobin from human whole blood, achieving high-purity hemoglobin as demonstrated by SDS-PAGE (polyacrylamide gel electrophoresis) assays.

  17. Anatase TiO{sub 2} hierarchical nanospheres with enhanced photocatalytic activity for degrading methyl orange

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Liqin; Xu, Wence [School of Materials Science and Engineering, Tianjin University, Tianjin, 300072 (China); Zhu, Shengli, E-mail: slzhu@tju.edu.cn [School of Materials Science and Engineering, Tianjin University, Tianjin, 300072 (China); Tianjin Key Laboratory of Composite and Functional Materials, Tianjin, 300072 (China); Cui, Zhenduo [School of Materials Science and Engineering, Tianjin University, Tianjin, 300072 (China); Yang, Xianjin [School of Materials Science and Engineering, Tianjin University, Tianjin, 300072 (China); Tianjin Key Laboratory of Composite and Functional Materials, Tianjin, 300072 (China); Inoue, Akihisa [School of Materials Science and Engineering, Tianjin University, Tianjin, 300072 (China); International Institute of Green Materials, Josai International University, Togane, 283-8555 (Japan)

    2016-02-15

    Anatase TiO{sub 2} hierarchical nanospheres were synthesized through a simple way combining dealloying and hydrothermal methods. The photocatalytic activity of the obtained products and Degussa P25 were evaluated by the degradation of methyl orange (MO) aqueous solution at different initial pH values and concentrations. The anatase TiO{sub 2} hierarchical nanospheres exhibited excellent photocatalytic activity for the degradation of methyl orange under ultraviolet–visible light irradiation. The photocatalytic efficiency of the anatase TiO{sub 2} increased with the decrease of pH at first then decreased and it also decreased with the increase of MO concentration. The superior photocatalytic performance of anatase TiO{sub 2} hierarchical nanospheres is attributed to its crystal phase, microstructure, and particularly surface acidity. The enhancement of surface acidity reduces the electron–hole pair recombination, and further increases the photocatalytic efficiency. - Highlights: • Anatase TiO{sub 2} nanospheres was prepared by chemical dealloying method. • The anatase TiO{sub 2} nanospheres exhibited good photocatalytic activity. • Sulfate ions adsorbed on TiO{sub 2} was beneficial for the photocatalytic performance.

  18. Nonlocal response of metallic nanospheres probed by light, electrons, and atoms.

    Science.gov (United States)

    Christensen, Thomas; Yan, Wei; Raza, Søren; Jauho, Antti-Pekka; Mortensen, N Asger; Wubs, Martijn

    2014-02-25

    Inspired by recent measurements on individual metallic nanospheres that cannot be explained with traditional classical electrodynamics, we theoretically investigate the effects of nonlocal response by metallic nanospheres in three distinct settings: atomic spontaneous emission, electron energy loss spectroscopy, and light scattering. These constitute two near-field and one far-field measurements, with zero-, one-, and two-dimensional excitation sources, respectively. We search for the clearest signatures of hydrodynamic pressure waves in nanospheres. We employ a linearized hydrodynamic model, and Mie-Lorenz theory is applied for each case. Nonlocal response shows its mark in all three configurations, but for the two near-field measurements, we predict especially pronounced nonlocal effects that are not exhibited in far-field measurements. Associated with every multipole order is not only a single blueshifted surface plasmon but also an infinite series of bulk plasmons that have no counterpart in a local-response approximation. We show that these increasingly blueshifted multipole plasmons become spectrally more prominent at shorter probe-to-surface separations and for decreasing nanosphere radii. For selected metals, we predict hydrodynamic multipolar plasmons to be measurable on single nanospheres.

  19. Hollow Sodium Tungsten Bronze (Na0.15WO3) Nanospheres: Preparation, Characterization, and Their Adsorption Properties.

    Science.gov (United States)

    Hou, Jing; Zuo, Guanke; Shen, Guangxia; Guo, He; Liu, Hui; Cheng, Ping; Zhang, Jingyan; Guo, Shouwu

    2009-07-17

    We report herein a facile method for the preparation of sodium tungsten bronzes hollow nanospheres using hydrogen gas bubbles as reactant for chemical reduction of tungstate to tungsten and as template for the formation of hollow nanospheres at the same time. The chemical composition and the crystalline state of the as-prepared hollow Na0.15WO3nanospheres were characterized complementarily, and the hollow structure formation mechanism was proposed. The hollow Na0.15WO3nanospheres showed large Brunauer-Emment-Teller specific area (33.8 m2 g-1), strong resistance to acids, and excellent ability to remove organic molecules such as dye and proteins from aqueous solutions. These illustrate that the hollow nanospheres of Na0.15WO3should be a useful adsorbent.

  20. Hollow Sodium Tungsten Bronze (Na0.15WO3 Nanospheres: Preparation, Characterization, and Their Adsorption Properties

    Directory of Open Access Journals (Sweden)

    Zuo Guanke

    2009-01-01

    Full Text Available Abstract We report herein a facile method for the preparation of sodium tungsten bronzes hollow nanospheres using hydrogen gas bubbles as reactant for chemical reduction of tungstate to tungsten and as template for the formation of hollow nanospheres at the same time. The chemical composition and the crystalline state of the as-prepared hollow Na0.15WO3nanospheres were characterized complementarily, and the hollow structure formation mechanism was proposed. The hollow Na0.15WO3nanospheres showed large Brunauer–Emment–Teller specific area (33.8 m2 g−1, strong resistance to acids, and excellent ability to remove organic molecules such as dye and proteins from aqueous solutions. These illustrate that the hollow nanospheres of Na0.15WO3should be a useful adsorbent.

  1. Conventional and microwave hydrothermal synthesis of monodispersed metal oxide nanoparticles at liquid-liquid interface

    Science.gov (United States)

    Monodispersed nanoparticles of metal oxide including ferrites MFe2O4 (M=, Ni, Co, Mn) and γ-Fe2O3, Ta2O5 etc. have been synthesized using a water-toluene interface under both conventional and microwave hydrothermal conditions. This general synthesis procedure uses readily availab...

  2. Monodispersed water-in-oil emulsions prepared with semi-metal microfluidic EDGE systems

    NARCIS (Netherlands)

    Maan, A.A.; Schroën, C.G.P.H.; Boom, R.M.

    2013-01-01

    Monodispersed water-in-oil emulsions were prepared with EDGE (Edge based Droplet GEneration) systems, which generate many droplets simultaneously from one junction. The devices (with plateau height of 1.0 µm) were coated with Cu and CuNi having the same hydrophobicity but different surface

  3. Lock and key colloids through polymerization-induced buckling of monodisperse silicon oil droplets

    NARCIS (Netherlands)

    Sacanna, S.|info:eu-repo/dai/nl/311471676; Irvine, W.T.M.; Rossi, L.|info:eu-repo/dai/nl/314410376; Pine, D.J.

    2011-01-01

    We have developed a new simple method to fabricate bulk amounts of colloidal spheres with well defined cavities from monodisperse emulsions. Herein, we describe the formation mechanism of ‘‘reactive’’ silicon oil droplets that deform to reproducible shapes via a polymerization-induced buckling

  4. Preparation and Photocatalytic Properties of Magnetically Separable Photocatalyst Nanospheres%可磁分离光催化剂的制备及其光催化性能研究

    Institute of Scientific and Technical Information of China (English)

    许士洪; 谭东栋; 毕得福; 时鹏辉; 李晔

    2013-01-01

    通过反胶束法和溶胶-凝胶法制备出了一种类蛋结构的可磁分离光催化剂纳米球ZnO@SiO2@NiFe2O4(ZSN),这种光催化剂显示出了超顺磁性和较好的光催化活性.该光催化剂的X-射线衍射和TEM分析结果表明:NiFe2O4纳米粒子被包裹在二氧化硅内形成磁性硅球SiO2@NiFe2O4 (SN)载体,ZnO纳米粒子包覆在SN的表面,形成ZnO光催化壳层.光催化实验表明,在500℃下煅烧3h的ZSN表现出最佳的光催化活性.%A novel magnetically separable photocatalyst nanosphere ZnO@SiO2@NiFe2O4 (ZSN) with egg-type structure was prepared by reverse micelles method and sol-gel method. The prepared photocatalyst shows superparamagnetic nature and high photocatalytic activity. XRD and TEM were used to characterize the structure of ZSN. The photocatalytic activity of ZSN was evaluated by degradation of methyl orange. The results indicated that the nickel ferrite cqre nanoparti-cles were completely encapsulated into the silica nanospheres as carrier, and the ZnO nanoparticles were coated onto the surface of the SN nanospheres, forming a ZnO shell for photocatalysis. The as-prepared ZSN calcined at 500 ℃ for 3 h presented the best photocatalytic activity.

  5. Aniline incorporated silica nanobubbles

    Indian Academy of Sciences (India)

    M J Rosemary; V Suryanarayanan; Ian Maclaren; T Pradeep

    2006-09-01

    We report the synthesis of stearate functionalized nanobubbles of SiO2 with a few aniline molecules inside, represented as C6H5NH2@SiO2@stearate, exhibiting fluorescence with red-shifted emission. Stearic acid functionalization allows the materials to be handled just as free molecules, for dissolution, precipitation, storage etc. The methodology adopted involves adsorption of aniline on the surface of gold nanoparticles with subsequent growth of a silica shell through monolayers, followed by the selective removal of the metal core either using sodium cyanide or by a new reaction involving halocarbons. The material is stable and can be stored for extended periods without loss of fluorescence. Spectroscopic and voltammetric properties of the system were studied in order to understand the interaction of aniline with the shell as well as the monolayer, whilst transmission electron microscopy has been used to study the silica shell.

  6. Low-temperature graphitization of amorphous carbon nanospheres

    Institute of Scientific and Technical Information of China (English)

    Katia Barbera; Leone Frusteri; Giuseppe Italiano; Lorenzo Spadaro; Francesco Frusteri; Siglinda Perathoner; Gabriele Centi

    2014-01-01

    The investigation by SEM/TEM, porosity, and X-ray diffraction measurements of the graphitization process starting from amorphous carbon nanospheres, prepared by glucose carbonization, is re-ported. Aspects studied are the annealing temperature in the 750-1000 °C range, the type of inert carrier gas, and time of treatment in the 2-6 h range. It is investigated how these parameters influ-ence the structural and morphological characteristics of the carbon materials obtained as well as their nanostructure. It is shown that it is possible to maintain after graphitization the round-shaped macro morphology, a high surface area and porosity, and especially a large structural disorder in the graphitic layers stacking, with the presence of rather small ordered domains. These are charac-teristics interesting for various catalytic applications. The key in obtaining these characteristics is the thermal treatment in a flow of N2. It was demonstrated that the use of He rather than N2 does not allow obtaining the same results. The effect is attributed to the presence of traces of oxygen, enough to create the presence of oxygen functional groups on the surface temperatures higher than 750 °C, when graphitization occurs. These oxygen functional groups favor the graphitization pro-cess.

  7. Enhanced cellulose degradation using cellulase-nanosphere complexes.

    Directory of Open Access Journals (Sweden)

    Craig Blanchette

    Full Text Available Enzyme catalyzed conversion of plant biomass to sugars is an inherently inefficient process, and one of the major factors limiting economical biofuel production. This is due to the physical barrier presented by polymers in plant cell walls, including semi-crystalline cellulose, to soluble enzyme accessibility. In contrast to the enzymes currently used in industry, bacterial cellulosomes organize cellulases and other proteins in a scaffold structure, and are highly efficient in degrading cellulose. To mimic this clustered assembly of enzymes, we conjugated cellulase obtained from Trichoderma viride to polystyrene nanospheres (cellulase:NS and tested the hydrolytic activity of this complex on cellulose substrates from purified and natural sources. Cellulase:NS and free cellulase were equally active on soluble carboxymethyl cellulose (CMC; however, the complexed enzyme displayed a higher affinity in its action on microcrystalline cellulose. Similarly, we found that the cellulase:NS complex was more efficient in degrading natural cellulose structures in the thickened walls of cultured wood cells. These results suggest that nanoparticle-bound enzymes can improve catalytic efficiency on physically intractable substrates. We discuss the potential for further enhancement of cellulose degradation by physically clustering combinations of different glycosyl hydrolase enzymes, and applications for using cellulase:NS complexes in biofuel production.

  8. Synthesis of novel porous magnetic silica microspheres as adsorbents for isolation of genomic DNA.

    Science.gov (United States)

    Zhang, Zhichao; Zhang, Liming; Chen, Lei; Chen, Ligong; Wan, Qian-Hong

    2006-01-01

    An improved procedure is described for preparation of novel mesoporous microspheres consisting of magnetic nanoparticles homogeneously dispersed in a silica matrix. The method is based on a three-step process, involving (i) formation of hematite/silica composite microspheres by urea-formaldehyde polymerization, (ii) calcination of the composite particles to remove the organic constituents, and (iii) in situ transformation of the iron oxide in the composites by hydrogen reductive reaction. The as-synthesized magnetite/silica composite microspheres were nearly monodisperse, mesoporous, and magnetizable, with as typical values an average diameter of 3.5 microm, a surface area of 250 m(2)/g, a pore size of 6.03 nm, and a saturation magnetization of 9.82 emu/g. These magnetic particles were tested as adsorbents for isolation of genomic DNA from Saccharomyces cerevisiae cells and maize kernels. The results are quite encouraging as the magnetic particle based protocols lead to the extraction of genomic DNA with satisfactory integrity, yield, and purity. Being hydrophilic in nature, the porous magnetic silica microspheres are considered a good alternative to polystyrene-based magnetic particles for use in biomedical applications where nonspecific adsorption of biomolecules is to be minimized.

  9. Preparation of Metalloporphyrin-Bound Superparamagnetic Silica Particles via "Click" Reaction.

    Science.gov (United States)

    Hollingsworth, Javoris V; Bhupathiraju, N V S Dinesh K; Sun, Jirun; Lochner, Eric; Vicente, M Graça H; Russo, Paul S

    2016-01-13

    A facile approach using click chemistry is demonstrated for immobilization of metalloporphyrins onto the surface of silica-coated iron oxide particles. Oleic-acid stabilized iron oxide nanocrystals were prepared by thermal decomposition of iron(III) acetylacetonate. Their crystallinity, morphology, and superparamagnetism were determined using X-ray diffraction, transmission electron microscopy, and a superconducting quantum interference device. Monodisperse core-shell particles were produced in the silica-coating of iron oxide via microemulsion synthesis. Surface modification of these particles was performed in two steps, which included the reaction of silica-coated iron oxide particles with 3-bromopropyltrichlorosilane, followed by azido-functionalization with sodium azide. Monoalkylated porphyrins were prepared using the Williamson ether synthesis of commercially available tetra(4-hydroxyphenyl) porphyrin with propargyl bromide in the presence of a base. (1)H NMR and matrix-assisted laser desorption ionization confirmed the identity of the compounds. The prepared monoalkyne porphyrins were zinc-metalated prior to their introduction to azide-functionalized, silica-coated iron oxide particles in the click reaction. X-ray photoelectron spectroscopy, thermogravimetric analysis, and Fourier transform infrared spectroscopy were used to characterize the surface chemistry after each step in the reaction. In addition, particle size was determined using dynamic light scattering and microscopy. The presented methodology is versatile and can be extended to other photoreactive systems, such as phthalocyanines and boron-dipyrromethane, which may lead to new materials for optical, photonic, and biological applications.

  10. Nanospheres caped Pt(II and Pt (IV: synthesis and evaluation as antimicrobial and Antifungal Agent

    Directory of Open Access Journals (Sweden)

    Öğütçü Hatice

    2017-03-01

    Full Text Available Antimicrobial and antifungal polymers are gaining the attention of pharmaceutical makers and industrial design. Nanospheres-Polymers attached Platinum(II / (IV complexes have been synthesized to investigate antimicrobial activities. Firstly, nanospheres involving Schiff bases were synthesized from (aminomethyl polystyrene and four substitute salicylaldehyde (2-hydroxy benzaldehyde, 5-fluoro-2-hydroxy benzaldehyde, 5-kloro-2-hydroxy benzaldehyde, 5-bromo-2-hydroxy benzaldehyde. Secondly, polymers attached Platinum(II / (IV complexes have been prepared by means of template method. The IR spectra show that the ligands act in a monovalent bidentate fashion all nanospheres involving Schiff bases. Square-planar and octahedral structures are proposed for Pt(II and Pt(IV, respectively. All these substances have been examined for antibacterial activity against pathogenic strains, and antifungal activity. In particular, Pt(IV complexes were more potent bactericides than all of the synthesized substances.

  11. Ultra-small and innocuous cationic starch nanospheres: preparation, characterization and drug delivery study.

    Science.gov (United States)

    Huang, Yinjuan; Liu, Mingzhu; Gao, Chunmei; Yang, Jinlong; Zhang, Xinyu; Zhang, Xinjie; Liu, Zhen

    2013-07-01

    This research demonstrated the preparation of ultra-small cationic starch nanospheres for the first time. Unlike conventional cationic starch, the cationic starch in here could not form gel. The starch nanoparticles were obtained via reverse micro-emulsion method and were characterized by Fourier transform infrared (FTIR) spectroscopy, Transmission electron microscopy (TEM) and Dynamic light scattering (DLS). The formation mechanism of cationic starch nanospheres was proposed and the effects of preparation conditions on particle size were also investigated. A cationic starch nanosphere with a size of 50 nm can be obtained under the optimal condition. Moreover, the drug release behaviors, cytotoxicity test and degradation analysis were tested and indicated that the particles possess good capacity in delivering the negatively charged molecules, biocompatibility and biodegradability. Thus, the cationic nanoparticles exhibit potential applications in the areas of food and medical sciences. Copyright © 2013 Elsevier B.V. All rights reserved.

  12. Efficient Overall Water-Splitting Electrocatalysis Using Lepidocrocite VOOH Hollow Nanospheres

    KAUST Repository

    Shi, Huanhuan

    2016-11-29

    Herein we report the control synthesis of lepidocrocite VOOH hollow nanospheres and further their applications in electrocatalytic water splitting for the first time. By tuning the surface area of the nanospheres, the optimal performance can be achieved with low overpotentials of 270 mV for the oxygen evolution reaction (OER) and 164 mV for the hydrogen evolution reaction (HER) at 10 mA cm-2 in 1 m KOH, respectively. Furthermore, when used as both the anode and cathode for overall water splitting, a low cell voltage of 1.62 V is required to reach the current density of 10 mA cm-2 , making the VOOH hollow nanospheres an efficient alternative to water splitting.

  13. Biodegradable black phosphorus-based nanospheres for in vivo photothermal cancer therapy

    Science.gov (United States)

    Shao, Jundong; Xie, Hanhan; Huang, Hao; Li, Zhibin; Sun, Zhengbo; Xu, Yanhua; Xiao, Quanlan; Yu, Xue-Feng; Zhao, Yuetao; Zhang, Han; Wang, Huaiyu; Chu, Paul K.

    2016-09-01

    Photothermal therapy (PTT) offers many advantages such as high efficiency and minimal invasiveness, but clinical adoption of PTT nanoagents have been stifled by unresolved concerns such as the biodegradability as well as long-term toxicity. Herein, poly (lactic-co-glycolic acid) (PLGA) loaded with black phosphorus quantum dots (BPQDs) is processed by an emulsion method to produce biodegradable BPQDs/PLGA nanospheres. The hydrophobic PLGA not only isolates the interior BPQDs from oxygen and water to enhance the photothermal stability, but also control the degradation rate of the BPQDs. The in vitro and in vivo experiments demonstrate that the BPQDs/PLGA nanospheres have inappreciable toxicity and good biocompatibility, and possess excellent PTT efficiency and tumour targeting ability as evidenced by highly efficient tumour ablation under near infrared (NIR) laser illumination. These BP-based nanospheres combine biodegradability and biocompatibility with high PTT efficiency, thus promising high clinical potential.

  14. A Multifunctional Subphthalocyanine Nanosphere for Targeting, Labeling, and Killing of Antibiotic-Resistant Bacteria.

    Science.gov (United States)

    Roy, Indranil; Shetty, Dinesh; Hota, Raghunandan; Baek, Kangkyun; Kim, Jeesu; Kim, Chulhong; Kappert, Sandro; Kim, Kimoon

    2015-12-01

    Developing a material that can combat antibiotic-resistant bacteria, a major global health threat, is an urgent requirement. To tackle this challenge, we synthesized a multifunctional subphthalocyanine (SubPc) polymer nanosphere that has the ability to target, label, and photoinactivate antibiotic-resistant bacteria in a single treatment with more than 99 % efficiency, even with a dose as low as 4.2 J cm(-2) and a loading concentration of 10 nM. The positively charged nanosphere shell composed of covalently linked SubPc units can increase the local concentration of photosensitizers at therapeutic sites. The nanosphere shows superior performance compared to corresponding monomers presumably because of their enhanced water dispersibility, higher efficiency of singlet-oxygen generation, and phototoxicity. In addition, this material is useful in fluorescence labeling of living cells and shows promise in photoacoustic imaging of bacteria in vivo.

  15. Facile Hydrothermal Synthesis of SnO2 Nanospheres as Photocatalysts

    Directory of Open Access Journals (Sweden)

    Wenquan Hu

    2017-01-01

    Full Text Available Large amounts of SnO2 nanospheres are successfully synthesized through a simple and effective hydrothermal method. The as-synthesized products consist of numerous small SnO2 nanocrystals with an average diameter of 40 nm. The as-prepared SnO2 nanospheres are further used as the photocatalysts for photodegrading several organic dyes (methylene blue, methyl orange, Congo red, and rhodamine B under UV light irradiation. The photocatalytic results show that the as-synthesized SnO2 nanospheres possess high photocatalytic activities. Compared with the degradation rates of other dyes, that of methylene blue reaches 98.5% by 30 min irradiation. It reveals that the as-prepared product might be potential candidate in wastewater purification.

  16. Nonlocal Response of Metallic Nanospheres Probed by Light, Electrons, and Atoms

    DEFF Research Database (Denmark)

    Christensen, Thomas; Yan, Wei; Raza, Søren

    2014-01-01

    Inspired by recent measurements on individual metallic nanospheres that cannot be explained with traditional classical electrodynamics, we theoretically investigate the effects of nonlocal response by metallic nanospheres in three distinct settings: atomic spontaneous emission, electron energy loss...... spectroscopy, and light scattering. These constitute two near-field and one far-field measurements, with zero-, one-, and two-dimensional excitation sources, respectively. We search for the clearest signatures of hydrodynamic pressure waves in nanospheres. We employ a linearized hydrodynamic model, and Mie......–Lorenz theory is applied for each case. Nonlocal response shows its mark in all three configurations, but for the two near-field measurements, we predict especially pronounced nonlocal effects that are not exhibited in far-field measurements. Associated with every multipole order is not only a single...

  17. Binary particle swarm optimization algorithm assisted to design of plasmonic nanospheres sensor

    Science.gov (United States)

    Kaboli, Milad; Akhlaghi, Majid; Shahmirzaee, Hossein

    2016-04-01

    In this study, a coherent perfect absorption (CPA)-type sensor based on plasmonic nanoparticles is proposed. It consists of a plasmonic nanospheres array on top of a quartz substrate. The refractive index changes above the sensor surface, which is due to the appearance of gas or the absorption of biomolecules, can be detected by measuring the resulting spectral shifts of the absorption coefficient. Since the CPA efficiency depends strongly on the number of plasmonic nanoparticles and the locations of nanoparticles, binary particle swarm optimization (BPSO) algorithm is used to design an optimized array of the plasmonic nanospheres. This optimized structure should be maximizing the absorption coefficient only in the one frequency. BPSO algorithm, a swarm of birds including a matrix with binary entries responsible for controlling nanospheres in the array, shows the presence with symbol of ('1') and the absence with ('0'). The sensor can be used for sensing both gas and low refractive index materials in an aqueous environment.

  18. Imaging plasmonic fields near gold nanospheres in attosecond time-resolved streaked photoelectron spectra

    Science.gov (United States)

    Li, Jianxiong; Thumm, Uwe

    2016-05-01

    To study time-resolved photoemission from gold nanospheres, we introduce a quantum-mechanical approach, including the plasmonic near-field-enhancement of the streaking field at the surface of the nanosphere. We use Mie theory to calculate the plasmonically enhanced fields near 10 to 200 nm gold nanospheres, driven by incident near infrared (NIR) or visible laser pulses. We model the gold conduction band in terms of a spherical square well potential. Our simulated streaked photoelectron spectra reveal a plasmonic amplitude enhancement and phase shift related to calculations that exclude the induced plasmonic field. The phase shift is due to the plasma resonance. This suggests the use of streaked photoelectron spectroscopy for imaging the dielectric response and plasmonic field near nanoparticles. Supported by the NSD-EPSCoR program, NSF, and the USDoE.

  19. Biodegradable black phosphorus-based nanospheres for in vivo photothermal cancer therapy

    Science.gov (United States)

    Shao, Jundong; Xie, Hanhan; Huang, Hao; Li, Zhibin; Sun, Zhengbo; Xu, Yanhua; Xiao, Quanlan; Yu, Xue-Feng; Zhao, Yuetao; Zhang, Han; Wang, Huaiyu; Chu, Paul K.

    2016-01-01

    Photothermal therapy (PTT) offers many advantages such as high efficiency and minimal invasiveness, but clinical adoption of PTT nanoagents have been stifled by unresolved concerns such as the biodegradability as well as long-term toxicity. Herein, poly (lactic-co-glycolic acid) (PLGA) loaded with black phosphorus quantum dots (BPQDs) is processed by an emulsion method to produce biodegradable BPQDs/PLGA nanospheres. The hydrophobic PLGA not only isolates the interior BPQDs from oxygen and water to enhance the photothermal stability, but also control the degradation rate of the BPQDs. The in vitro and in vivo experiments demonstrate that the BPQDs/PLGA nanospheres have inappreciable toxicity and good biocompatibility, and possess excellent PTT efficiency and tumour targeting ability as evidenced by highly efficient tumour ablation under near infrared (NIR) laser illumination. These BP-based nanospheres combine biodegradability and biocompatibility with high PTT efficiency, thus promising high clinical potential. PMID:27686999

  20. Ag Nanoparticles Array and Ordered Nanoshells Synthesized by Nanosphere Lithography%基于纳米球刻蚀的银纳米颗粒阵列和有序纳米壳层的制备

    Institute of Scientific and Technical Information of China (English)

    刘斌斌; 肖湘衡; 吴伟; 任峰; 蒋昌忠

    2011-01-01

    Through using floating-transferring method modified by introduction of a slide,the monodisperse PS particles can self-assemble to two-dimensional(2D) colloidal crystals with compact hexagonal structure under appropriate conditions.The experimental results indicate that a ordered arrangement region with a large area of 50 μm×50 μm is obtained besides a few of line defects.Based on a combination of nanosphere lithography and e-beam evaporation deposition technique,triangular shaped silver nanoparticles arrays have been fabricated successfully when PS colloidal crystals are served as mask.Simultaneously,PS nanospheres can be regarded as scrificial nanosphere template to guide the formation of bowl-shaped nanoshells,providing a facile method to synthesize such nanostructure.This approach can be expanded to other materials.Additionally,different sizes of the latex spheres can be chosen to produce triangular nanoparticles array and nanoshells with other sizes.%通过经引流片改进的"漂移法",使单分散聚苯乙烯球胶体颗粒成功自组装形成按六角密排结构的二维胶体晶体.实验结果表明,除存在极少量的线缺陷,可得到大面积(50μm×50μm)的PS球有序排列区域.以上述聚苯乙烯球胶体晶体作为掩膜板,用纳米球刻蚀和电子束蒸镀技术相结合的方法,成功地制备了三角形的银纳米颗粒阵列.以聚苯乙烯球作为"牺牲"纳米球模板,得到了一种简单有效的制备碗状银纳米壳层的方法.这种方法可拓展到其他材料,可通过选择不同粒径的PS球来控制贵金属纳米颗粒的大小和制备不同尺寸的纳米壳层.

  1. Multilayered silica-biopolymer nanocapsules with a hydrophobic core and a hydrophilic tunable shell thickness

    Science.gov (United States)

    Vecchione, Raffaele; Luciani, Giuseppina; Calcagno, Vincenzo; Jakhmola, Anshuman; Silvestri, Brigida; Guarnieri, Daniela; Belli, Valentina; Costantini, Aniello; Netti, Paolo A.

    2016-04-01

    Stable, biocompatible, multifunctional and multicompartment nanocarriers are much needed in the field of nanomedicine. Here, we report a simple, novel strategy to design an engineered nanocarrier system featuring an oil-core/hybrid polymer/silica-shell. Silica shells with a tunable thickness were grown in situ, directly around a highly mono-disperse and stable oil-in-water emulsion system, stabilized by a double bio-functional polyelectrolyte heparin/chitosan layer. Such silica showed a complete degradation in a physiological medium (SBF) in a time frame of three days. Moreover, the outer silica shell was coated with polyethyleneglycol (PEG) in order to confer antifouling properties to the final nanocapsule. The outer silica layer combined its properties (it is an optimal bio-interface for bio-conjugations and for the embedding of hydrophilic drugs in the porous structure) with the capability to stabilize the oil core for the confinement of high payloads of lipophilic tracers (e.g. CdSe quantum dots, Nile Red) and drugs. In addition, polymer layers - besides conferring stability to the emulsion while building the silica shell - can be independently exploited if suitably functionalized, as demonstrated by conjugating chitosan with fluorescein isothiocyanate. Such numerous features in a single nanocarrier system make it very intriguing as a multifunctional platform for smart diagnosis and therapy.Stable, biocompatible, multifunctional and multicompartment nanocarriers are much needed in the field of nanomedicine. Here, we report a simple, novel strategy to design an engineered nanocarrier system featuring an oil-core/hybrid polymer/silica-shell. Silica shells with a tunable thickness were grown in situ, directly around a highly mono-disperse and stable oil-in-water emulsion system, stabilized by a double bio-functional polyelectrolyte heparin/chitosan layer. Such silica showed a complete degradation in a physiological medium (SBF) in a time frame of three days

  2. Supercapacitive Properties of 3D-Arrayed Polyaniline Hollow Nanospheres Encaging RuO2 Nanoparticles.

    Science.gov (United States)

    Kwon, Hyemin; Hong, Dajung; Ryu, Ilhwan; Yim, Sanggyu

    2017-03-01

    A major limitation of polyaniline (PANi) electrodes for supercapacitors is the slow rate of ion transport during redox reactions and the resultant easy saturation of areal capacitance with film thickness. In this study, three-dimensionally (3D)-arrayed PANi nanospheres with highly roughened surface nanomorphology were fabricated to overcome this limitation. A hierarchical nanostructure was obtained by polymerizing aniline monomers on a template of 3D-arrayed polystyrene (PS) nanospheres and appropriate oxidative acid doping. The structure provided dramatically increased surface area and porosity that led to the efficient diffusion of ions. Thus, the specific capacitance (Csp) reached 1570 F g(-1), thereby approaching a theoretical capacitance of PANi. In addition, the retention at a high scan rate of 100 mV s(-1) was 77.6% of the Csp at a scan rate of 10 mV s(-1). Furthermore, 3D-arrayed hollow PANi (H-PANi) nanospheres could be obtained by dissolving the inner PS part of the PS/PANi core/shell nanospheres with tetrahydrofuran. The ruthenium oxide (RuO2) nanoparticles (NPs) were also encaged in the H-PANi nanospheres by embedding RuO2 NPs on the PS nanospheres prior to polymerization of PANi. The combination of the two active electrode materials indicated synergetic effects. The areal capacitance of the RuO2-encaged PANi electrode was significantly larger than that of the RuO2-free PANi electrode and could be controlled by varying the amount of encaged RuO2 nanoparticles. The encagement could also solve the problem of detachment of RuO2 electrodes from the current collector. The effects of the nanostructuring and RuO2 encagement were also quantitatively analyzed by deconvoluting the total capacitance into the surface capacitive and insertion elements.

  3. Specific Heat of Hollow Nanosphere Coupled to Substrate: Quantum Size Effects

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    With the help of the elastic wave theory, in the perturbed approximation the density-of-states for vibrational modes and the specific heat axe studied for different hollow Si nanospheres, coupled with a semi-infinite substrate. We find that the modes of such coupled hollow spheres are significantly broadened and shifted toward low frequencies. The specific heat of the coupled hollow nanosphere is bigger than an isolated one due to the coupling interaction and quantum size effects. The predicted coupling and size enhancements on specific heat are probed in thermal experiments.

  4. SnO2 nanospheres supported Pd catalyst with enhanced performance for formic acid oxidation

    Science.gov (United States)

    Lu, Haiting; Fan, Yang; Huang, Ping; Xu, Dongli

    2012-10-01

    SnO2 nanospheres were employed as the support material for Pd catalyst. The as-prepared Pd/SnO2 catalyst exhibited remarkably improved electrocatalytic activity and stability towards formic acid oxidation, in comparison with that of the Vulcan XC-72 carbon black and the commercial SnO2 nanopowder supported Pd catalyst. The enhanced catalytic performance may arise from the unique structure and surface properties of the SnO2 nanospheres, which process extraordinary promotional effect on Pd catalyst.

  5. Storage and sustained release of volatile substances from a hollow silica matrix

    Energy Technology Data Exchange (ETDEWEB)

    Wang Jiexin [Key Lab for Nanomaterials, Ministry of Education, Beijing 100029 (China); Ding Haomin [Research Center of the Ministry of Education for High Gravity Engineering and Technology, Beijing University of Chemical Technology, Beijing 100029 (China); Tao Xia [Key Lab for Nanomaterials, Ministry of Education, Beijing 100029 (China); Chen Jianfeng [Key Lab for Nanomaterials, Ministry of Education, Beijing 100029 (China)

    2007-06-20

    Porous hollow silica nanospheres (PHSNSs) prepared by adopting a nanosized CaCO{sub 3} template were utilized for the first time as a novel carrier for the storage and sustained release of volatile substances. Two types of volatile substances, Indian pipal from perfumes and peroxyacetic acid from disinfectants, were selected and then tested by one simple adsorption process with two separate comparative carriers, i.e. activated carbon and solid porous silica. It was demonstrated that a high storage capacity (9.6 ml{sub perfume}/mg{sub carrier}) of perfume could be achieved in a PHSNS matrix, which was almost 14 times as much as that of activated carbon. The perfume release profiles showed that PHSNSs exhibited sustained multi-stage release behaviour, while the constant release of activated carbon at a low level was discerned. Further, a Higuchi model study proved that the release process of perfume in both carriers followed a Fickian diffusion mechanism. For peroxyacetic acid as a disinfectant model, PHSNSs also displayed a much better delayed-delivery process than a solid porous silica system owing to the existence of unique hollow frameworks. Therefore, the aforementioned excellent sustained-release behaviours would make PHSNSs a promising carrier for storage and sustained delivery applications of volatile substances.

  6. Durable superhydrophobic and antireflective surfaces by trimethylsilanized silica nanoparticles-based sol-gel processing.

    Science.gov (United States)

    Manca, Michele; Cannavale, Alessandro; De Marco, Luisa; Aricò, Antonino S; Cingolani, Roberto; Gigli, Giuseppe

    2009-06-02

    We present a robust and cost-effective coating method to fabricate long-term durable superhydrophobic andsimultaneouslyantireflective surfaces by a double-layer coating comprising trimethylsiloxane (TMS) surface-functionalized silica nanoparticles partially embedded into an organosilica binder matrix produced through a sol-gel process. A dense and homogeneous organosilica gel layer was first coated onto a glass substrate, and then, a trimethylsilanized nanospheres-based superhydrophobic layer was deposited onto it. After thermal curing, the two layers turned into a monolithic film, and the hydrophobic nanoparticles were permanently fixed to the glass substrate. Such treated surfaces showed a tremendous water repellency (contact angle = 168 degrees ) and stable self-cleaning effect during 2000 h of outdoor exposure. Besides this, nanotextured topology generated by the self-assembled nanoparticles-based top layer produced a fair antireflection effect consisting of more than a 3% increase in optical transmittance.

  7. Progammed synthesis of magnetic mesoporous silica coated carbon nanotubes for organic pollutant adsorption

    Energy Technology Data Exchange (ETDEWEB)

    Tong, Yue; Zhang, Min, E-mail: congmingyang123@163.com; Xia, Peixiong; Wang, Linlin; Zheng, Jing; Li, Weizhen; Xu, Jingli, E-mail: xujingli@sues.edu.cn

    2016-05-15

    Magnetic mesoporous silica coated carbon nanotubes were produced from hydrophilic monodisperse magnetic nanoparticles decorated carbon nanotubes using well controlled programmed synthesis method and were characterized by TEM, XRD, FTIR, TGA, N{sub 2} adsorption–desorption and VSM. The well-designed mesoporous magnetic nanotubes had a large specific area, a highly open mesoporous structure and high magnetization. Firstly, SiO{sub 2}-coated maghemite/CNTs nanoparticles (CNTs/Fe{sub 3}O{sub 4}@SiO{sub 2} composites) were synthesized by the combination of high temperature decomposition process and an sol–gel method, in which the iron acetylacetonate as well as TEOS acted as the precursor for maghemite and SiO{sub 2}, respectively. The CNTs/Fe{sub 3}O{sub 4}@SiO{sub 2} composites revealed a core–shell structure, Then, CNTs/Fe{sub 3}O{sub 4}@mSiO{sub 2} was obtained by extracting cetyltrimethylammonium bromide (CTAB) via an ion-exchange procedure. The resulting composites show not only a magnetic response to an externally applied magnetic field, but also can be a good adsorbent for the organic pollutant in the ambient temperature. - Graphical abstract: Magnetic mesoporous silica coated carbon nanotubes were produced from hydrophilic monodisperse magnetic nanoparticles decorated carbon nanotubes using well controlled programmed synthesis, which can be a good adsorbent for the organic pollutant in the ambient temperature. - Highlights: • The surface of CNTs/Fe{sub 3}O{sub 4} is hydrophilic, which facilitates the silica coating. • The CNTs/Fe{sub 3}O{sub 4}@mSiO{sub 2} was synthesized by a facile method. • The CNTs/Fe{sub 3}O{sub 4}@mSiO{sub 2} can be a good adsorbent for the organic pollutant.

  8. Hydrothermal stability of microporous silica and niobia-silica membranes

    NARCIS (Netherlands)

    Boffa, V.; Blank, David H.A.; ten Elshof, Johan E.

    2008-01-01

    The hydrothermal stability of microporous niobia–silica membranes was investigated and compared with silica membranes. The membranes were exposed to hydrothermal conditions at 150 and 200 °C for 70 h. The change of pore structure before and after exposure to steam was probed by single-gas permeation

  9. Dispersion of nano-silica in monomer casting nylon6 and its effect on the structure and properties of composites

    Directory of Open Access Journals (Sweden)

    2010-07-01

    Full Text Available To promote dispersion of nano-silica in monomer casting nylon6 (MC nylon6, nano-silica was dispersed in melted caprolactam with the assistance of ultrasound, anionic polymerization was then initiated to form silica/MC nylon6 in-situ nanocomposites. It was found that hydrogen bonds were formed between nano-silica and caprolactam, in the meantime, ultrasound helped to break the nanoparticles aggregations into smaller ones or even mono-dispersing particles. Therefore, the agglomerated nanoparticles were pulled apart and stabilized by caprolactam. Additionally, the rapid anionic polymerization of caprolactam also contributed to the avoidance of re-agglomeration and deposition of nanoparticles during the polymerization process, leading to the uniform distribution of nanoparticles in the polymer matrix. Mechanical tests indicated that the silica/MC nylon6 in-situ nanocomposites prepared according to the above strategy were simultaneously toughened, strengthened and stiffened. Thermogravimetric analysis (TGA results showed that thermal stability of nanocomposites was notably improved compared to neat MC nylon6.

  10. Non-hydrolytic formation of silica and polysilsesquioxane particles from alkoxysilane monomers with formic acid in toluene/tetrahydrofuran solutions

    Science.gov (United States)

    Boday, Dylan J.; Tolbert, Stephanie; Keller, Michael W.; Li, Zhe; Wertz, Jason T.; Muriithi, Beatrice; Loy, Douglas A.

    2014-03-01

    Silica and polysilsesquioxane particles are used as fillers in composites, catalyst supports, chromatographic separations media, and even as additives to cosmetics. The particles are generally prepared by hydrolysis and condensation of tetraalkoxysilanes and/or organotrialkoxysilanes, respectively, in aqueous alcohol solutions. In this study, we have discovered a new, non-aqueous approach to prepare silica and polysilsesquioxane particles. Spherical, nearly monodisperse, silica particles (600-6,000 nm) were prepared from the reaction of tetramethoxysilane with formic acid (4-8 equivalents) in toluene or toluene/tetrahydrofuran solutions. Polymerization of organotrialkoxysilanes with formic acid failed to afford particles, but bridged polysilsesquioxane particles were obtained from monomers with two trialkoxysilyl group attached to an organic-bridging group. The mild acidic conditions allowed particles to be prepared from monomers, such as bis(3-triethoxysilylpropyl)tetrasulfide, which are unstable to Stöber or base-catalyzed emulsion polymerization conditions. The bridged polysilsesquioxane particles were generally less spherical and more polydisperse than silica particles. Both silica and bridged polysilsesquioxane nanoparticles could be prepared in good yields at monomer concentrations considerably higher than used in Stöber or emulsion approaches.

  11. Fabrication, characterization and application of nitrogen-containing carbon nanospheres obtained by pyrolysis of lignosulfonate/poly(2-ethylaniline).

    Science.gov (United States)

    He, Zhi-Wei; Lü, Qiu-Feng; Lin, Qilang

    2013-01-01

    Lignosulfonate/poly(2-ethylaniline) (LS-PEA) composite nanospheres were prepared via in situ polymerization of 2-ethylaniline (EA) with lignosulfonate (LS) as a dispersant. LS-PEA nanospheres with an average diameter of 155 nm were obtained at an optimal LS concentration of 20 wt.%. Subsequently, nitrogen-containing carbon nanospheres were fabricated via direct pyrolysis of the LS-PEA composite nanospheres at 600-800 °C. The carbon nanospheres prepared by pyrolysis were used as anodes of lithium-ion batteries. The first charge and discharge capacity of carbon nanospheres prepared at 700 °C at current densities of 60 and 100 mA g(-1) were 980 and 432 mAh g(-1), and 764 and 342 mAh g(-1), respectively. The batteries still owned a high capacity of 353 and 296 mAh g(-1) after 20 cycles. The results indicated that these nitrogen-containing carbon nanospheres could be used as a promising candidate for electrode materials of lithium-ion batteries.

  12. Temperature-responsive polymeric nanospheres containing methotrexate and gold nanoparticles: A multi-drug system for theranostic in rheumatoid arthritis.

    Science.gov (United States)

    Costa Lima, Sofia A; Reis, Salette

    2015-09-01

    Inflammation plays a crucial role in rheumatoid arthritis progress. In the present work, a novel stealth polymeric nanospheres platform able to carry anti-inflammatory drugs and an imaging agent was developed. Incorporation of gold nanoparticles will allow photoacoustic imaging and near infra-red photothermal application. Through emulsion-diffusion evaporation technique methotrexate and gold nanoparticles were incorporated in the pegylated-poly(DL-lactic-co-glycolic acid) nanospheres. In vitro drug release assays revealed pH and temperature-dependence on gold nanoparticles. Blank nanospheres exhibited negligible in vitro cytotoxicity, while methotrexate-loaded nanospheres hampered monocytes and macrophages viability at a higher level than free methotrexate. Confocal fluorescent microscopy and flow cytometry revealed effective nanospheres internalization, and that their cellular uptake was energy dependent mediated by caveolae and clathrin-endocytosis mechanism. Finally, MTX-loaded multifunctional nanospheres containing gold lead to a significant reduction of IL-1β, IL-6 and TNF-α inflammatory cytokines produced by monocytes and macrophages upon in vitro inflammatory stimulation, suggesting a favorable anti-inflammatory activity. These results confirm that the multifunctional nanospheres represent a promising theranostic platform for RA diagnosis and intracellular treatment, by combining methotrexate and gold nanoparticles for a highly effective targeted chemo-photothermal therapy.

  13. Quantum dots-hyperbranched polyether hybrid nanospheres towards delivery and real-time detection of nitric oxide

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Shuiping; Gu, Tianxun; Fu, Jiajia [Key Laboratory of Eco-Textiles, Ministry of Education (Jiangnan University), Wuxi 214122 (China); College of Textile and Clothing, Jiangnan University, Wuxi 214122 (China); Li, Xiaoqiang, E-mail: leecaiwei@163.com [Key Laboratory of Eco-Textiles, Ministry of Education (Jiangnan University), Wuxi 214122 (China); College of Textile and Clothing, Jiangnan University, Wuxi 214122 (China); Technical University of Denmark, DTU Food, Søltofts plads, B227, 2800 Kgs. Lyngby (Denmark); Chronakis, Ioannis S. [Technical University of Denmark, DTU Food, Søltofts plads, B227, 2800 Kgs. Lyngby (Denmark); Ge, Mingqiao [Key Laboratory of Eco-Textiles, Ministry of Education (Jiangnan University), Wuxi 214122 (China); College of Textile and Clothing, Jiangnan University, Wuxi 214122 (China)

    2014-12-01

    In this work, novel hybrid nanosphere vehicles were synthesized for nitric oxide (NO) donating and real-time detection. The hybrid nanosphere vehicles consist of cadmium selenide quantum dots (CdSe QDs) as NO fluorescent probes, and the modified hyperbranched polyether (mHP)-based diazeniumdiolates as NO donors, respectively. The nanospheres have spherical outline with dimension of ∼ 127 nm. The data of systematic characterization demonstrated that the mHP-based hybrid nanosphere vehicles (QDs-mHP-NO) can release and real-time detect NO with the low limit of 25 nM, based on fluorescence quenching mechanism. The low cell-toxicity of QDs-mHP-NO nanospheres was verified by means of MTT assay on L929 cells viability. The QDs-mHP-NO nanospheres provide perspectives for designing a new class of biocompatible NO donating and imaging systems. - Highlights: • QDs-mHP-NO fluorescent probe was prepared. • The QDs-mHP-NO probe is capable of releasing NO. • The QDs-mHP-NO probe can quantitatively detecting the release of NO in real time. • The low cell-toxicity of QDs-mHP-NO nanospheres was verified.

  14. Silica Micro Encapsulation

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, P.; Whitbread-Jordan, M. [KEECO (United Kingdom)

    2001-04-01

    The article explains how Silica Micro Encapsulation (SME) water treatment technology may be transferred from metal mining to coal mining operations. KEECO has been developing a unique solution for treating acid rock drainage in the metal sulphide mining sector and following trials in metal mining operations (described in the article), is preparing to transfer the technology to the coal industry. SME technology comprises metal precipitation and encapsulation accomplished with proprietary chemical, KB-1, and a group of patented chemical dosing systems, the K-series, to dose KB-1 into contaminated liquid wastes as a dry powder. 4 figs., 4 tabs.

  15. ZBLAN, Silica Fiber Comparison

    Science.gov (United States)

    1998-01-01

    This graph depicts the increased signal quality possible with optical fibers made from ZBLAN, a family of heavy-metal fluoride glasses (fluorine combined zirconium, barium, lanthanum, aluminum, and sodium) as compared to silica fibers. NASA is conducting research on pulling ZBLAN fibers in the low-g environment of space to prevent crystallization that limits ZBLAN's usefulness in optical fiber-based communications. In the graph, a line closer to the black theoretical maximum line is better. Photo credit: NASA/Marshall Space Flight Center

  16. Efficient removal and highly selective adsorption of Hg{sup 2+} by polydopamine nanospheres with total recycle capacity

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiulan [School of Chemistry and Chemical Engineering, Key Laboratory for Green Processing of Chemical Engineering of Xinjiang bingtuan, Shihezi University, Shihezi 832003 (China); Jia, Xin, E-mail: jiaxin@shzu.edu.cn [School of Chemistry and Chemical Engineering, Key Laboratory for Green Processing of Chemical Engineering of Xinjiang bingtuan, Shihezi University, Shihezi 832003 (China); Zhang, Guoxiang [Gansu Dayu Water-saving Group Co., Ltd, Jiuquan 735000 (China); Hu, Jiamei; Sheng, Wenbo; Ma, Zhiyuan; Lu, Jianjiang; Liu, Zhiyong [School of Chemistry and Chemical Engineering, Key Laboratory for Green Processing of Chemical Engineering of Xinjiang bingtuan, Shihezi University, Shihezi 832003 (China)

    2014-09-30

    Highlights: • The PDA nanospheres with uniform diameter of 150–200 nm were used to remove Hg{sup 2+} efficiently and selectively. • The desorption capacity of PDA nanospheres was 100% in pH 1. • The structure and removal capacity of PDA nanospheres remained almost unchanged after recycling five times. - Abstract: This study reported a new method for efficient removal of Hg{sup 2+} from contaminated water using highly selective adsorptive polydopamine (PDA) nanospheres, which were uniform and had a small diameter (150–200 nm). The adsorption isotherms, kinetics, thermodynamics were investigated. Also, the effects of ionic strength, co-existing ions on removing ability of PDA nanospheres for Hg{sup 2+} were studied. Adsorption of Hg{sup 2+} was very fast and efficient as adsorption equilibrium was completed within 4 h and the maximum adsorption capacities were 1861.72 mg/g, 2037.22 mg/g, and 2076.81 mg/g at 298 K, 313 K, and 328 K respectively, increasing with increasing of temperature. The PDA nanospheres exhibited highly selective adsorption of Hg{sup 2+} and had a total desorption capacity of 100% in hydrochloric acid solution, pH 1. The results showed that the structure of PDA nanospheres remained almost unchanged after recycling five times. Furthermore, X-ray photoelectron spectroscopy (XPS) was employed to determine the elements of PDA nanospheres before and after Hg{sup 2+} adsorption. Considering their efficient and highly Hg{sup 2+} selective adsorption, total recycle capacity, and high stability, PDA nanospheres will be feasible in a number of practical applications.

  17. Specificity of lectin-immobilized fluorescent nanospheres for colorectal tumors in a mouse model which more resembles the clinical disease

    Science.gov (United States)

    Kitamura, Tokio; Sakuma, Shinji; Shimosato, Moe; Higashino, Haruki; Masaoka, Yoshie; Kataoka, Makoto; Yamashita, Shinji; Hiwatari, Ken-ichiro; Kumagai, Hironori; Morimoto, Naoki; Koike, Seiji; Tobita, Etsuo; Hoffman, Robert M.; Gore, John C.; Pham, Wellington

    2014-01-01

    We are investigating an imaging agent that enables real-time and accurate diagnosis of early colorectal cancer at the intestinal mucosa by colonoscopy. The imaging agent is peanut agglutinin-immobilized polystyrene nanospheres with surface poly(N-vinylacetamide) chains encapsulating coumarin 6. Intracolonically-administered lectin-immobilized fluorescent nanospheres detect tumor-derived changes through molecular recognition of lectin for the terminal sugar of cancer-specific antigens on the mucosal surface. The focus of this study was to evaluate imaging abilities of the nanospheres in animal models that reflect clinical environments. We previously developed an orthotopic mouse model with human colorectal tumors growing on the mucosa of the descending colon to more resemble the clinical disease. The entire colon of the mice in the exposed abdomen was monitored in real-time with an in vivo imaging apparatus. Fluorescence from the nanospheres was observed along the entire descending colon after intracolonical administration of them from the anus. When the luminal side of the colon was washed with PBS, most of the nanospheres drained away. However, fluorescence persisted in areas where the cancer cells were implanted. Histological evaluation demonstrated that tumors were present in the mucosal epithelia where the nanospheres fluoresced. In contrast, no fluorescence was observed when control mice without tumors were tested. The lectin-immobilized fluorescent nanospheres were tumor specific and bound to tumors even after vigorously washing. The nanospheres non-specifically bound to normal mucosa were easily removed through mild washing. Results indicate that the nanospheres accompanied by colonoscopy will be a clinically-valuable diagnostic tool for the early stage primary colon carcinoma. PMID:24976331

  18. 类蛋结构的可磁分离光催化剂纳米球的制备及催化性能%Preparation and Photocatalytic Properties of Magnetically Separable Photocatalyst Nanospheres with Egg-like Structure

    Institute of Scientific and Technical Information of China (English)

    许士洪; 赵松建; 谭东栋; 时鹏辉; 毕得福

    2012-01-01

    A novel magnetically separable photocatalyst nanosphere TiO2@ SiO2@ NiFe2O4(TSN) with egg-like structure was prepared by reverse micelles method and electrostatic self-assembly method. The photocatalyst shows high photocatalytic activity for the degradation of methyl orange in water. The magnetic property measurements indicate that the photocatalyst possesses a superparamagnetic nature, which can be separated and recycled conveniently through an external magnetic field. X-ray diffractometer ( XRD) and transmission electron microscope ( TEM) were used to characterize the structure of the TSN photocatalyst nanosphere. The results indicate that nickel ferrite core nanoparticles are completely encapsulated into silica nanospheres as carrier, and titania nanoparticles are assembled onto the surface of SN nanospheres, forming a TiO2 shell for photocatalysis. The SiO2 layer between the NiFe2O4 core and the TiO2 shell effectively prevents the injection of charges from TiO2 particles to NiFe2O4, which gives rise to an increase in photocatalytic activity.%通过反胶束和静电自组装方法制备了一种类蛋结构的可磁分离光催化剂纳米材料SiO2@NiFe2O4@TiO2( TSN),这种光催化剂对甲基橙废水有较好的降解效果,并显示出了超顺磁性,通过外加磁场方便地实现催化剂在水中的分离与回收.该光催化剂纳米球的X射线衍射、TEM和FTIR结果表明,铁酸镍纳米粒子被包裹在SiO2内,形成SiO2@NiFe2O4(SN)纳米球载体,纳米TiO2颗粒组装在SN表面,形成TiO2光催化壳层.利用甲基橙的降解考察了光催化剂纳米球的活性,结果表明,在NiFe2O4和TiO2之间包覆一层无定形的SiO2可以显著提高光催化剂纳米球TSN的催化活性.

  19. Shape-tunable hollow silica nanomaterials based on a soft-templating method and their application as a drug carrier.

    Science.gov (United States)

    Chen, Jiao; Wu, Xu; Hou, Xiaodong; Su, Xingguang; Chu, Qianli; Fahruddin, Nenny; Zhao, Julia Xiaojun

    2014-12-24

    A one-step soft-templating method for synthesizing shape-tunable hollow silica nanomaterials was developed in a reliable and highly reproducible way. For the first time, both nonspherical and spherical shapes with hollow interiors, including nanowire, nanospheres, and nanotadpole, were successfully obtained by simply changing the solvent. Poly(vinylpyrrolidone) (PVP)-water droplets were used as soft templates for the formation of hollow structures, while three different solvents, including 1-propanol, 1-pentanol, and ethanol, led to the designed shapes. It was found that the solvent, the formation of PVP-water droplets, the amount of ammonia, and the reaction time had great effects on the morphology of synthesized hollow nanomaterials. The effect of various factors on the morphology was systematically studied to propose a growth mechanism. The obtained hollow silica nanomaterials showed excellent reproducibility and great potential for a large-scale synthesis. Finally, the application of the developed hollow silica nanomaterials was demonstrated using the hollow spherical silica nanoparticles. Its drug-carrying ability was studied. The results could be extended for doping various target molecules into the hollow structures for a broad range of applications.

  20. Synthesis of hematite α-Fe{sub 2}O{sub 3} nanospheres for lithium ion battery applications

    Energy Technology Data Exchange (ETDEWEB)

    Rao, B. Nageswara; Padmaraj, O.; Kumar, P. Ramesh; Satyanarayana, N., E-mail: nallanis2011@gmail.com [Department of Physics, Pondicherry University, Pondicherry-605014 (India); Venkateswarlu, M. [R& D, Amaraja batteries, Tirupati-517501, A.P. (India); Rao, V. Madhusudhan [Vignan University, Vadlamudi, Guntur, 522 213, A.P. (India)

    2015-06-24

    Hematite α-Fe{sub 2}O{sub 3} nanospheres were prepared by a rapid microwave assisted hydrothermal process. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy studies confirm the phase and structural coordination of α-Fe{sub 2}O{sub 3} respectively. The formation of uniform shape of nanospheres α-Fe{sub 2}O{sub 3} was confirmed from the results scanning electron microscopy (SEM). Galvanostatic battery testing shows that the α-Fe{sub 2}O{sub 3} nanospheres exhibit good electrochemical performance in the voltage range 0.002 - 3 V.

  1. Hierarchical SnO2 Nanospheres: Bio-inspired Mineralization, Vulcanization, Oxidation Techniques, and the Application for NO Sensors

    Science.gov (United States)

    Wang, Lei; Chen, Yuejiao; Ma, Jianmin; Chen, Libao; Xu, Zhi; Wang, Taihong

    2013-12-01

    Controllable synthesis and surface engineering of nanomaterials are of strategic importance for tailoring their properties. Here, we demonstrate that the synthesis and surface adjustment of highly stable hierarchical of SnO2 nanospheres can be realized by biomineralization, vulcanization and oxidation techniques. Furthermore, we reveal that the highly stable hierarchical SnO2 nanospheres ensure a remarkable sensitivity towards NO gas with fast response and recovery due to their high crystallinity and special structure. Such technique acquiring highly stable hierarchical SnO2 nanospheres offers promising potential for future practical applications in monitoring the emission from waste incinerators and combustion process of fossil fuels.

  2. Effect of Mixed Solvent on Fabrication, Morphology and Monodispersity of Microspheres with Hydrophobic Poly(butyl methacrylate) Shells

    Institute of Scientific and Technical Information of China (English)

    XIAO Xincai; LU Cheng

    2012-01-01

    Monodisperse microspheres (mean diameter 200-300 nm) with polystyrene cores and poly(acrylamide-co-buty1 methacrylate) shells were prepared by using a free radical polymerization method.Moreover,the effect of mixed solvent on the preparation,morphology and monodispersity was investigated.The experimental results showed that solubility parameter of butyl methacrylate and solvent affected mainly the molding of monodisperse core-shell microspheres.When the microspheres were fabricated in a sequential synthesis process,addition of hydrophilic and organic solvent including butyl methacrylate led to spherical degree of the particles becoming worse,and the mean diameter of the microspheres decreased and the monodispersity became better with increasing the crosslinker methylenebisacrylamide dosage.

  3. Ferroelectric behavior of a lead titanate nanosphere due to depolarization fields and mechanical stresses

    Energy Technology Data Exchange (ETDEWEB)

    Andrade Landeta, J.; Lascano, I.

    2017-07-01

    A theorical model has been developed based on the theory of Ginzburg-Landau-Devonshire to study and predict the effects the decreasing of size particle in a nanosphere of PbTiO3 subjected to the action of depolarization fields and mechanical stress. It was considered that the nanosphere is surrounded by a layer of space charges on its surface, and containing 180° domains generated by minimizing free energy of depolarization. Energy density of depolarization, wall domain and electro-elastic energy have been incorporated into the free energy of the theory Ginzburg-Landau-Devonshire. Free energy minimization was performed to determine the spontaneous polarization and transition temperature system. These results show that the transition temperature for nanosphere is substantially smaller than the corresponding bulk material. Also, it has been obtained that the stability of the ferroelectric phase of nanosphere is favored for configurations with a large number of 180° domains, with the decreasing of thickness space charge layer, and the application of tensile stress and decreases with compressive stress. (Author)

  4. Gold Functionalized Platinum M12L24-Nanospheres and Their Application in Cyclization Reactions

    NARCIS (Netherlands)

    Leenders, S.H.A.M.; Dürr, M.; Ivanović-Burmazović, I.; Reek, J.N.H.

    2016-01-01

    Nanospheres can be formed by combining 24 bispyridinyl building blocks with a palladium or platinum precursor. These spheres can be functionalized on the inside with a gold(I) chloride complex leading to a high local concentration of gold(I) complexes. The high local concentration makes the neutral

  5. Encapsulation of anticancer drug and magnetic particles in biodegradable polymer nanospheres

    Energy Technology Data Exchange (ETDEWEB)

    Koneracka, M; Zavisova, V; Tomasovicova, N; Kopcansky, P; Timko, M; JurIkova, A; Csach, K; Kavecansky, V; Lancz, G [Institute of Experimental Physics, Slovak Academy of Sciences, Watsonova 47, Kosice (Slovakia); Muckova, M [Hameln rds a.s., Horna 36, Modra (Slovakia)], E-mail: konerack@saske.sk

    2008-05-21

    In this study, we have prepared PLGA (poly-D,L-lactide-co-glycolide) nanospheres loaded with biocompatible magnetic fluid and anticancer drug taxol by a modified nanoprecipitation technique and investigated their magnetic properties. A magnetic fluid, MF-PEG, with a biocompatible layer of polyethylene glycol (PEG), was chosen as a magnetic carrier. The PLGA, whose copolymer ratio of D,L-lactide to glycolide is 85:15, was utilized as a capsulation material. Taxol, as an important anticancer drug, was chosen for its significant role against a wide range of tumours. The morphology and particle size distributions of the prepared nanospheres were investigated by transmission electron microscopy (TEM) and scanning electron microscopy (SEM) and showed a spherical shape of prepared nanospheres with size 250 nm. Infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and thermogravimetry (TGA) analysis confirmed incorporation of magnetic particles and taxol into the PLGA polymer. The results showed good encapsulation with magnetite content 21.5 wt% and taxol 0.5 wt%. Magnetic properties of magnetic fluids and taxol within the PLGA polymer matrix were investigated by SQUID magnetometry from 4.2 to 300 K. The SQUID measurements showed superparamagnetism of prepared nanospheres with a blocking temperature of 160 K and saturation magnetization 1.4 mT.

  6. Synthesis of ZnS hollow nanospheres with holes using different amine templates

    Institute of Scientific and Technical Information of China (English)

    Eingang LI; Yu TANG; Yuanming ZHANG; Jun YANG; Biying DU

    2008-01-01

    ZnS hollow nanospheres with holes were prepared by reacting ZnSO4 with H2S, the sulfide source formed in the reaction of CS2 with ethylenediamine, 1,3-propylenediamine, butylamine or 2-(2-aminoethylamino) ethanol, which also acted as a template agent, at 50℃ under agitation. The shape, particle size of about 100-850 nm and hole size of about 150-600 nm of ZnS hollow nanospheres with holes were shown by SEM and TEM images. These ZnS nanospheres with β cubic ZnS phase and composed of 2-5 nm nanocrystals were characterized by XRD and HRTEM. The blue shift of maximum absorption in UV-vis displayed the effect of quantum size. The two amino groups of amine templates reacted favorably with Zn2+ to form uniform and relatively smooth ZnS nanospheres with holes, while hydroxyethyl played a disadvantageous role. A reason-able mechanism of hole formation by H2S rushing out is suggested.

  7. Synthesis and characterization of ZnS@Fe3O4 fluorescent-magnetic bifunctional nanospheres

    Science.gov (United States)

    Koc, Kenan; Karakus, Baris; Rajar, Kausar; Alveroglu, Esra

    2017-10-01

    Herein, we synthesized and characterized fluorescent and super paramagnetic ZnS@Fe3O4 nanospheres. First, (3-mercaptopropyl) trimethoxysilane (MPS) capped ZnS quantum dots (QDs) and SiO2 coated Fe3O4 nanoparticles were synthesized separately by using solution growth and co-precipitation techniques. After synthesis and characterization of these two nanoparticles, they were conglutinated together in a nano sized sphere. The QDs were attached to the surface of the Fe3O4 nanoparticles by Sisbnd Osbnd Si bonds and so Sisbnd Osbnd Si bonds created a SiO2 network around the nanoparticles during the formation of the ZnS@Fe3O4 nanospheres. The synthesized MPS capped ZnS fluorescent QDs, SiO2 coated magnetite super paramagnetic nanoparticles and ZnS@Fe3O4 fluorescent-magnetic bifunctional nanospheres were characterized by using UV-Vis Absorption Spectroscopy, Fluorescence Spectroscopy, X-ray analysis, Vibrating Sample Magnetometer analysis, Attenuated Total Reflection-Fourier Transform Infrared Spectroscopy, Scanning Electron Microscope and Energy-dispersive X-ray spectroscopy. ZnS@Fe3O4 bifunctional nanospheres were shown to retain the magnetic properties of magnetite, while exhibiting the luminescent optical properties of ZnS nanoparticles. The combination of fluorescent and magnetic behaviors of nano composites make them useful for potential applications in the field of bio-medical and environmental.

  8. Synthesis of sulfonated porous carbon nanospheres solid acid by a facile chemical activation route

    Science.gov (United States)

    Chang, Binbin; Guo, Yanzhen; Yin, Hang; Zhang, Shouren; Yang, Baocheng

    2015-01-01

    Generally, porous carbon nanospheres materials are usually prepared via a template method, which is a multi-steps and high-cost strategy. Here, we reported a porous carbon nanosphere solid acid with high surface area and superior porosity, as well as uniform nanospheical morphology, which prepared by a facile chemical activation with ZnCl2 using resorcinol-formaldehyde (RF) resins spheres as precursor. The activation of RF resins spheres by ZnCl2 at 400 °C brought high surface area and large volume, and simultaneously retained numerous oxygen-containing and hydrogen-containing groups due to the relatively low processing temperature. The presence of these functional groups is favorable for the modification of -SO3H groups by a followed sulfonation treating with sulphuric acid and organic sulfonic acid. The results of N2 adsorption-desorption and electron microscopy clearly showed the preservation of porous structure and nanospherical morphology. Infrared spectra certified the variation of surface functional groups after activation and the successful modification of -SO3H groups after sulfonation. The acidities of catalysts were estimated by an indirect titration method and the modified amount of -SO3H groups were examined by energy dispersive spectra. The results suggested sulfonated porous carbon nanospheres catalysts possessed high acidities and -SO3H densities, which endowed their significantly catalytic activities for biodiesel production. Furthermore, their excellent stability and recycling property were also demonstrated by five consecutive cycles.

  9. Eco-friendly synthesis of colloidal silver nanospheres, nanorings and nanonetworks

    NARCIS (Netherlands)

    Singh, A.K.; Rai, A.K.; Bicanic, D.D.

    2009-01-01

    Colloidal silver nanospheres, nanorings, and nanonetworks were synthesized by the nanosecond pulsed laser ablation of a silver metal plate in a pure distilled water (at room temperature) using the fundamental (1064 nm), second harmonic (532 nm), and third harmonic (355 nm) wavelengths of the Nd:YAG

  10. Facile synthesis of PdSx/C porous nanospheres and their applications for ethanol oxidation reaction

    Science.gov (United States)

    Zhang, Qiang; Zhang, Fuhua; Ma, Xuemei; Zheng, Yiqun; Hou, Shifeng

    2016-12-01

    We report a facile approach for the synthesis of carbon-supported palladium polysulphide porous nanospheres (PdSx/C) and their applications for ethanol oxidation reaction. Typical synthesis started with generation of palladium/poly (3,4-ethylenedioxythiophene)(Pd/PEDOT) nanospheres, followed by a calcination process at an optimized temperature to form PdSx/C, with an average size of 2.47 ± 0.60 and 50 nm of PdSx nanoparticles and carbon porous nanospheres, respectively. Various techniques, such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and electrochemical techniques were performed to characterize their morphologies, compositions and structures. In contrary to most Pd-based electrochemical catalysts that could be easily poised with trace sulfur during the catalytic oxidation process, the as-prepared PdSx/C porous nanospheres exhibited high electrocatalytic activities and stabilities for the electrochemical catalytic oxidation of ethanol in alkaline medium. In particular, the forward peak current intensity achieved 162.1 mA mg-1 and still maintained at 46.7 mA mg-1 even after 1000 cycles. This current work not only offers a novel type of fuel-cell catalyst for ethanol oxidation reaction, but also provides a possible route for solving the sulfur-poisoning problem in catalysis.

  11. Eco-friendly synthesis of colloidal silver nanospheres, nanorings and nanonetworks

    NARCIS (Netherlands)

    Singh, A.K.; Rai, A.K.; Bicanic, D.D.

    2009-01-01

    Colloidal silver nanospheres, nanorings, and nanonetworks were synthesized by the nanosecond pulsed laser ablation of a silver metal plate in a pure distilled water (at room temperature) using the fundamental (1064 nm), second harmonic (532 nm), and third harmonic (355 nm) wavelengths of the Nd:YAG

  12. Influence of the Molecular Weight and Charge of Antibiotics on Their Release Kinetics From Gelatin Nanospheres.

    Science.gov (United States)

    Song, Jiankang; Odekerken, Jim C E; Löwik, Dennis W P M; López-Pérez, Paula M; Welting, Tim J M; Yang, Fang; Jansen, John A; Leeuwenburgh, Sander C G

    2015-07-01

    In this study, we investigated the fundamental relationship between the physicochemical characteristics of antibiotics and the kinetics of their release from gelatin nanospheres. We observed that antibiotics of high molecular weight (colistin and vancomycin) were released in a sustained manner from oppositely charged gelatin carriers for more than 14 d, as opposed to antibiotics of low molecular weight (gentamicin and moxifloxacin) which were released in a burst-like manner. The release kinetics of positively charged colistin strongly correlated with the rate of the enzymatic degradation of gelatin. To elucidate the differences among release kinetics of antibiotics, we explored the mechanism of interactions between antibiotics and gelatin nanospheres by monitoring the kinetics of release of antibiotics as a function of pH, ionic strength, and detergent concentrations. These studies revealed that the interactions between antibiotics and gelatin nanospheres were mainly dominated by (i) strong electrostatic forces for colistin; (ii) strong hydrophobic and electrostatic forces for vancomycin; (iii) weak electrostatic and hydrophobic forces for gentamicin; and (iv) weak hydrophobic forces for moxifloxacin. These results confirm that release of antibiotics from gelatin nanospheres strongly depends on the physicochemical characteristics of the antibiotics. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Dual protection of sulfur by carbon nanospheres and graphene sheets for lithium-sulfur batteries.

    Science.gov (United States)

    Wang, Bei; Wen, Yanfen; Ye, Delai; Yu, Hua; Sun, Bing; Wang, Guoxiu; Hulicova-Jurcakova, Denisa; Wang, Lianzhou

    2014-04-25

    Well-confined elemental sulfur was implanted into a stacked block of carbon nanospheres and graphene sheets through a simple solution process to create a new type of composite cathode material for lithium-sulfur batteries. Transmission electron microscopy and elemental mapping analysis confirm that the as-prepared composite material consists of graphene-wrapped carbon nanospheres with sulfur uniformly distributed in between, where the carbon nanospheres act as the sulfur carriers. With this structural design, the graphene contributes to direct coverage of sulfur to inhibit the mobility of polysulfides, whereas the carbon nanospheres undertake the role of carrying the sulfur into the carbon network. This composite achieves a high loading of sulfur (64.2 wt %) and gives a stable electrochemical performance with a maximum discharge capacity of 1394 mAh g(-1) at a current rate of 0.1 C as well as excellent rate capability at 1 C and 2 C. The improved electrochemical properties of this composite material are attributed to the dual functions of the carbon components, which effectively restrain the sulfur inside the carbon nano-network for use in lithium-sulfur rechargeable batteries.

  14. Polydopamine-based superparamagnetic molecularly imprinted polymer nanospheres for efficient protein recognition.

    Science.gov (United States)

    Lan, Fang; Ma, Shaohua; Yang, Qi; Xie, Liqin; Wu, Yao; Gu, Zhongwei

    2014-11-01

    A new strategy for synthesis of superparamagnetic molecularly imprinted polymer nanospheres (MIPNSs) for efficient protein recognition is described here. Homogeneous hydroxyl group functionalized Fe3O4/polymethyl methacrylate (PMMA) composite nanospheres were prepared using improved miniemulsion polymerization. Uniform superparamagnetic MIPNSs were obtained via self-polymerization of dopamine (DA) on the surface of Fe3O4/PMMA composite nanospheres in the presence of lysozyme (lyz) template. The as-synthesized Fe3O4/PMMA/PDA MIPNSs had average diameters of 180 nm, high saturation magnetization and a good magnetic response. The lyz-imprinted Fe3O4/PMMA/PDA MIPNSs exhibited specific recognition and efficient adsorption capacity toward lyz template. The amount of lyz adsorbed onto the lyz-imprinted Fe3O4/PMMA/PDA MIPNSs was about 4 times greater than that of the Fe3O4/PMMA/PDA non-imprinted polymer nanospheres (NIPNSs) and about 14, 5, and 5 times greater than that of BSA, BHb, and cyt C, respectively. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Formation mechanism of monodisperse, low molecular weight chitosan nanoparticles by ionic gelation technique.

    Science.gov (United States)

    Fan, Wen; Yan, Wei; Xu, Zushun; Ni, Hong

    2012-02-01

    Chitosan nanoparticles have been extensively studied for drug and gene delivery. In this paper, monodisperse, low molecular weight (LMW) chitosan nanoparticles were prepared by a novel method based on ionic gelation using sodium tripolyphosphate (TPP) as cross-linking agent. The objective of this study was to solve the problem of preparation of chitosan/TPP nanoparticles with high degree of monodispersity and stability, and investigate the effect of various parameters on the formation of LMW chitosan/TPP nanoparticles. It was found that the particle size distribution of the nanoparticles could be significantly narrowed by a combination of decreasing the concentration of acetic acid and reducing the ambient temperature during cross-linking process. The optimized nanoparticles exhibited a mean hydrodynamic diameter of 138 nm with a polydispersity index (PDI) of 0.026 and a zeta potential of +35 mV, the nanoparticles had good storage stability at room temperature up to at least 20 days.

  16. Controlled Synthesis and Characterization of Monodisperse Fe3O4 Nanoparticles

    Institute of Scientific and Technical Information of China (English)

    SHI,Rongrong; GAO,Guanhua; YI,Ran; ZHOU,Kechao; QIU,Guanzhou; LIU,Xiaohe

    2009-01-01

    Monodisperse Fe3O4 nanoparticles were successfully synthesized through the thermal decomposition of iron acetylacetonate in octadecene solvent in the presence of oleic acid and oleylamine.The influences of experimental parameters,such as reacting temperature,amounts and kinds of surfactants,solvents,oleic acid and oleylamine,on the size and shape of monodisperse Fe3O4 nanoparticles were discussed.The phase structures,morphology,and size of the as-prepared products were investigated in detail by X-ray diffraction (XRD),transmission electron microscopy (TEM),selected area electron diffraction (SAED) and high-resolution transmission electron microscopy (HRTEM).Magnetic property was measured using a vibrating sample magnetometer (VSM) at room temperature,which revealed that Fe3O4 nanoparticles were of ferromagnetism with a saturation magnetization (Ms) of 74.0 emu/g and coercivity (Hc) of 72.6 Oe.

  17. Simple and inexpensive microfluidic devices for the generation of monodisperse multiple emulsions

    KAUST Repository

    Li, Erqiang

    2013-12-16

    Droplet-based microfluidic devices have become a preferred versatile platform for various fields in physics, chemistry and biology. Polydimethylsiloxane soft lithography, the mainstay for fabricating microfluidic devices, usually requires the usage of expensive apparatus and a complex manufacturing procedure. Here, we report the design and fabrication of simple and inexpensive microfluidic devices based on microscope glass slides and pulled glass capillaries, for generating monodisperse multiple emulsions. The advantages of our method lie in a simple manufacturing procedure, inexpensive processing equipment and flexibility in the surface modification of the designed microfluidic devices. Different types of devices have been designed and tested and the experimental results demonstrated their robustness for preparing monodisperse single, double, triple and multi-component emulsions. © 2014 IOP Publishing Ltd.

  18. Micro-spherical cochleate composites: method development for monodispersed cochleate system.

    Science.gov (United States)

    Nagarsekar, Kalpa; Ashtikar, Mukul; Steiniger, Frank; Thamm, Jana; Schacher, Felix H; Fahr, Alfred

    2017-03-01

    Cochleates have been of increasing interest in pharmaceutical research due to their extraordinary stability. However the existing techniques used in the production of cochleates still need significant improvements to achieve sufficiently monodispersed formulations. In this study, we report a simple method for the production of spherical composite microparticles (3-5 μm in diameter) made up of nanocochleates from phosphatidylserine and calcium (as binding agent). Formulations obtained from the proposed method were evaluated using electron microscopy and small angle X-ray scattering and were compared with conventional cochleate preparation techniques. In this new method, an ethanolic lipid solution and aqueous solution of a binding agent is subjected to rapid and uniform mixing with a microfluidic device. The presence of high concentration of organic solvent promotes the formation of composite microparticles made of nanocochleates. This simple methodology eliminates elaborate preparation methods, while providing a monodisperse cochleate system with analogous quality.

  19. Enhanced thermal stability of monodispersed silver cluster arrays assembled on block copolymer scaffolds

    Energy Technology Data Exchange (ETDEWEB)

    Xu, C H; Chen, X; Liu, Y J; Xie, B; Han, M [National Laboratory of Solid State Microstructures and Department of Materials Science and Engineering, Nanjing University, Nanjing 210093 (China); Song, F Q; Wang, G H, E-mail: sjhanmin@nju.edu.cn [National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093 (China)

    2010-05-14

    Triblock copolymer poly(styrene-b-butadiene-b-styrene) (SBS) films with long-range ordered self-assembled nanopatterns are used as templates to selectively adsorb soft-landing silver clusters. Closely spaced cluster arrays with high monodispersity are formed through the confinement of the block copolymer scaffolds, and show a much enhanced thermal stability as compared with the cluster assemblies on the surfaces of covalent amorphous solids, or even on the disordered SBS films. Their morphologies are barely influenced by long time thermal annealing at a temperature as high as 180 deg. C, while in the latter case intense aggregations and coalescences of silver clusters are commonly observed upon annealing. The different thermal stabilities of the cluster assemblies also induce different evolutions of their optical extinction spectra under annealing. This promises a simple way to control the monodispersity and thermal stability of metal cluster assembly via self-assembled block copolymer template.

  20. A granocentric model captures the statistical properties of monodisperse random packings

    CERN Document Server

    Newhall, Katherine A; Vanden-Eijnden, Eric; Brujic, Jasna

    2012-01-01

    We present a generalization of the granocentric model proposed in [Clusel et al., Nature, 2009, 460, 611615] that is capable of describing the local fluctuations inside not only polydisperse but also monodisperse packings of spheres. This minimal model does not take into account the relative particle positions, yet it captures positional disorder through local stochastic processes sampled by efficient Monte Carlo methods. The disorder is characterized by the distributions of local parameters, such as the number of neighbors and contacts, filled solid angle around a central particle and the cell volumes. The model predictions are in good agreement with our experimental data on monodisperse random close packings of PMMA particles. Moreover, the model can be used to predict the distributions of local fluctuations in any packing, as long as the average number of neighbors, contacts and the packing fraction are known. These distributions give a microscopic foundation to the statistical mechanics framework for jamm...

  1. Understanding and Controlling the Growth of Monodisperse CdS Nanowires in Solution

    DEFF Research Database (Denmark)

    Xi, Lifei; Tan, Winnie Xiu Wen; Boothroyd, Chris;

    2008-01-01

    diffusion rate of the precursor and hence low reactivity. Therefore, ODPA is good for generating nearly monodisperse and high aspect ratio US nanowires. Our nanowires have a high degree of dispersibility and thus can be easily processed for potential applications as solar cells and transistors. Finally......Cadmium sulfide (CdS) nanowires with a monodisperse diameter of 3.5 nm and length of about 600 nm were successfully synthesized using a simple and reproducible hot coordination solvents method. Structural characterization showed that the one-dimensional nanowires grow along the [001] direction......, we propose that the ODPA-to-Cd mole ratio is the key factor affecting the morphology of the nanowires because it affects both the cleavage rate of the P=S double bond and the nucleation/growth rate of the anisotropic nanocrystals. In addition, it was found that Cd-ODPA complexes give rise to a low...

  2. Fabrication of monodisperse magnetic nanoparticles released in solution using a block copolymer template

    Science.gov (United States)

    Morcrette, Mélissa; Ortiz, Guillermo; Tallegas, Salomé; Joisten, Hélène; Tiron, Raluca; Baron, Thierry; Hou, Yanxia; Lequien, Stéphane; Bsiesy, Ahmad; Dieny, Bernard

    2017-07-01

    This paper describes a fabrication process of monodisperse magnetic nanoparticles released in solution, based on combined ‘top-down’ and ‘bottom-up’ approaches. The process involves the use of a self-assembled PS-PMMA block copolymer formed on a sacrificial layer. Such an approach was so far mostly explored for the preparation of patterned magnetic media for ultrahigh density magnetic storage. It is here extended to the preparation of released monodisperse nanoparticles for biomedical applications. A special sacrificial layer had to be developed compatible with the copolymer self-organization. The resulting nanoparticles exhibit very narrow size dispersion (≈7%) and can be good candidates as contrast agents for medical imaging i.e. magnetic resonance imaging or magnetic particle imaging. The approach provides a great freedom in the choice of the particles shapes and compositions. In particular, they can be made of biocompatible magnetic material.

  3. Production of nearly monodisperse Fe3O4 and Fe@Fe3O4 nanoparticles in aqueous medium and their surface modification for biomedical applications

    Science.gov (United States)

    Tegafaw, Tirusew; Xu, Wenlong; Lee, Sang Hyup; Chae, Kwon Seok; Chang, Yongmin; Lee, Gang Ho

    2017-02-01

    Iron (Fe)-based nanoparticles are extremely valuable in biomedical applications owing to their low toxicity and high magnetization values at room temperature. In this study, we synthesized nearly monodisperse iron oxide (Fe3O4) and Fe@Fe3O4 (core: Fe, shell: Fe3O4) nanoparticles in aqueous medium under argon flow and then, coated them with various biocompatible ligands and silica. In this study, eight types of surface-modified nanoparticles were investigated, namely, Fe3O4@PAA (PAA = polyacrylic acid; Mw of PAA = 5100 amu and 15,000 amu), Fe3O4@PAA-FA (FA = folic acid; Mw of PAA = 5100 amu and 15,000 amu), Fe3O4@PEI-fluorescein (PEI = polyethylenimine; Mw of PEI = 1300 amu), Fe@Fe3O4@PEI (Mw of PEI = 10,000 amu), Fe3O4@SiO2 and Fe@Fe3O4@SiO2 nanoparticles. We characterized the prepared surface-modified nanoparticles using high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) absorption spectroscopy, a superconducting quantum interference device (SQUID), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectroscopy and confocal microscopy. Finally, we measured the cytotoxicity of the samples. The results indicate that the surface-modified nanoparticles are biocompatible and are potential candidates for various biomedical applications.

  4. Mesoporous Silica Nanomaterials for Applications in Catalysis, Sensing, Drug Delivery and Gene Transfection

    Energy Technology Data Exchange (ETDEWEB)

    Radu, Daniela Rodica [Iowa State Univ., Ames, IA (United States)

    2004-01-01

    The central theme of this dissertation is represented by the versatility of mesoporous silica nanomaterials in various applications such as catalysis and bio-applications, with main focus on biological applications of Mesoporous Silica Nanospheres (MSN). The metamorphosis that we impose to these materials from catalysis to sensing and to drug and gene delivery is detailed in this dissertation. First, we developed a synthetic method that can fine tune the amount of chemically accessible organic functional groups on the pores surface of MSN by exploiting electrostatic and size matching between the cationic alkylammonium head group of the cetyltrimethylammonium bromide (CTAB) surfactant and various anionic organoalkoxysilane precursors at the micelle-water interface in a base-catalyzed condensation reaction of silicate. Aiming nature imitation, we demonstrated the catalytic abilities of the MSNs, We utilized an ethylenediamine functional group for chelating Cu2+ as a catalytic functional group anchored inside the mesopores. Thus, a polyalkynylene-based conducting polymer (molecular wire) was synthesized within the Cu-functionalized MSNs silica catalyst. For sensing applications, we have synthesized a poly(lactic acid) coated mesoporous silica nanosphere (PLA-MSN) material that serves as a fluorescence sensor system for detection of amino-containing neurotransmitters in neutral aqueous buffer. We exploited the mesoporosity of MSNs for encapsulating pharmaceutical drugs. We examined bio-friendly capping molecules such as polyamidoamine dendrimers of generations G2 to G4, to prevent the drug leaching. Next, the drug delivery system employed MSNs loaded with Doxorubicin, an anticancer drug. The results demonstrated that these nano-Trojan horses have ability to deliver Doxorubicin to cancer cells and induce their death. Finally, to demonstrate the potential of MSN as an universal cellular transmembrane nanovehicle, we anchored positively charged dendrimers on

  5. Mesoporous Silica Nanomaterials for Applications in Catalysis, Sensing, Drug Delivery and Gene Transfection

    Energy Technology Data Exchange (ETDEWEB)

    Daniela Rodica Radu

    2005-12-19

    The central theme of this dissertation is represented by the versatility of mesoporous silica nanomaterials in various applications such as catalysis and bio-applications, with main focus on biological applications of Mesoporous Silica Nanospheres (MSN). The metamorphosis that we impose to these materials from catalysis to sensing and to drug and gene delivery is detailed in this dissertation. First, we developed a synthetic method that can fine tune the amount of chemically accessible organic functional groups on the pores surface of MSN by exploiting electrostatic and size matching between the cationic alkylammonium head group of the cetyltrimethylammonium bromide (CTAB) surfactant and various anionic organoalkoxysilane precursors at the micelle-water interface in a base-catalyzed condensation reaction of silicate. Aiming nature imitation, we demonstrated the catalytic abilities of the MSNs, We utilized an ethylenediamine functional group for chelating Cu{sup 2+} as a catalytic functional group anchored inside the mesopores. Thus, a polyalkynylene-based conducting polymer (molecular wire) was synthesized within the Cu-functionalized MSNs silica catalyst. For sensing applications, we have synthesized a poly(lactic acid) coated mesoporous silica nanosphere (PLA-MSN) material that serves as a fluorescence sensor system for detection of amino-containing neurotransmitters in neutral aqueous buffer. We exploited the mesoporosity of MSNs for encapsulating pharmaceutical drugs. We examined bio-friendly capping molecules such as polyamidoamine dendrimers of generations G2 to G4, to prevent the drug leaching. Next, the drug delivery system employed MSNs loaded with Doxorubicin, an anticancer drug. The results demonstrated that these nano-Trojan horses have ability to deliver Doxorubicin to cancer cells and induce their death. Finally, to demonstrate the potential of MSN as an universal cellular transmembrane nanovehicle, we anchored positively charged dendrimers on the

  6. Towards Cluster-Assembled Materials of True Monodispersity in Size and Chemical Environment: Synthesis, Dynamics and Activity

    Science.gov (United States)

    2016-10-27

    pathway Status: not yet published Diverse technologies, from catalyst coking to graphene synthesis , entail hydrocarbon dehydrogena- tion and...AFRL-AFOSR-UK-TR-2016-0037 Towards cluster-assembled materials of true monodispersity in size and chemical environment: Synthesis , Dynamics and...Towards cluster-assembled materials of true monodispersity in size and chemical environment: synthesis , dynamics and activity 5a.  CONTRACT NUMBER 5b

  7. Facile synthesis of CdS/C core–shell nanospheres with ultrathin carbon layer for enhanced photocatalytic properties and stability

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jing [Department of Chemistry, Zhejiang Normal University, Jinhua 321004 (China); Zhang, Fu [Department of Medical Materials and Rehabilitation Engineering, School of Medical Engineering, Hefei University of Technology, Hefei 230009 (China); Zhao, Yu-Ling, E-mail: yulingzhao@zjnu.cn [Department of Chemistry, Zhejiang Normal University, Jinhua 321004 (China); Guo, Yan-Chuan [Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Gong, Peijun [Department of Chemistry, Zhejiang Normal University, Jinhua 321004 (China); Li, Zheng-Quan, E-mail: zqli@zjnu.cn [Department of Chemistry, Zhejiang Normal University, Jinhua 321004 (China); Qian, Hai-Sheng, E-mail: shqian@hfut.edu.cn [Department of Medical Materials and Rehabilitation Engineering, School of Medical Engineering, Hefei University of Technology, Hefei 230009 (China)

    2016-01-30

    Graphical abstract: Uniform CdS/C core–shell nanospheres with several nanometers in thickness for carbon shell have been synthesized successfully; which show enhanced photocatalytic activities than single-component counterparts (CdS nanospheres). - Highlights: • The CdS/C nanospheres have been synthesized by a facile hydrothermal method. • The CdS/C nanospheres showed enhanced photocatalytic properties and photostability. • The as-prepared CdS/C core-shell nanospheres show better biocompatibility. - Abstract: In this work, we described a facile one-pot hydrothermal process developed to synthesize CdS/C core–shell nanospheres successfully. The as-prepared CdS/C core–shell nanospheres are with 100 nm in diameter and the amorphous carbon shell is with several nanometers in thickness. The phase, morphology and structures of the samples were investigated by X-ray power diffraction (XRD) analyses, field-emission scanning electron microscopy (FESEM, JEOL-6700F) and transmission electron microscopy (TEM, JEOL 3010); respectively. The as-prepared CdS/C core–shell nanospheres showed enhanced photocatalytic properties and photostability compared to the single counterpart of CdS nanospheres owing to the efficiently separation of photogenerated electrons (e{sup −}) and holes (h{sup +}) derived from the photocatalyst. In addition, the as-prepared CdS/C core–shell nanospheres might find wide application in wastewater treatment, solar cells, lithium ion batteries, etc.

  8. Size reduction of cosolvent-infused microbubbles to form acoustically responsive monodisperse perfluorocarbon nanodroplets.

    Science.gov (United States)

    Seo, Minseok; Williams, Ross; Matsuura, Naomi

    2015-09-07

    Perfluorocarbon (PFC) nanodroplet agents are exciting new biomaterials that can be remotely vapourized by ultrasound or light to change into micron-scale gas bubbles in situ. After PFC nanodroplet vapourization, the micron-scale gas bubble can interact strongly with ultrasound radiation, such that the bubbles can be used for cancer imaging and therapy. For these phase-change agents to be useful, however, PFC nanodroplets must be produced in the range of 100 to 400 nm in diameter with high size control and monodispersity, restrictions that remain a challenge. Here, we address this challenge by taking advantage of the size control offered by microfluidics, in combination with the size reduction provided by cosolvent-infused PFC bubbles through both condensation and cosolvent dissolution. In this approach, PFC bubbles with a high percentage of cosolvent (in this study, diethyl ether, DEE) are produced using microfluidics at a temperature above the boiling point. After synthesis, these bubbles become much smaller through both condensation of the gas into liquid droplets and from dissolution of the DEE into the continuous phase. This approach demonstrates that monodisperse, cosolvent-incorporated PFC bubbles can directly form monodisperse PFC nanodroplets a factor of 24 times smaller than the precursor bubbles. We also demonstrate that these nanoscale droplets can be converted to echogenic microbubbles after exposure to ultrasound, showing that these PFC nanodroplets are viable for the in situ production of ultrasound contrast agents. We show that this system can overcome the minimum droplet size limit of standard microfluidics, and is a powerful new tool for generating monodisperse, PFC phase-change ultrasound contrast agents for treating and imaging cancer.

  9. On sufficient stability conditions of the Couette — Poiseuille flow of monodisperse mixture

    Science.gov (United States)

    Popov, D. I.; Sagalakov, A. M.; Nikitenko, N. G.

    2011-06-01

    The stability of the Couette — Poiseuille flow of a monodisperse mixture is considered. Sufficient stability conditions are derived. Results of the computation of the spectrum are presented. A considerable stabilization of the flow with particles admixture to small disturbances is observed. It is found that the regions of instability generation may have complex geometry. The influence of the main velocity profile and admixture parameters on the stability conditions is considered.

  10. Enhancement of magnetic coercivity and macroscopic quantum tunneling in monodispersed Co/CoO cluster assemblies

    OpenAIRE

    Peng, D. L.; Sumiyama, Kenji; Hihara, Takehiko; Yamamuro, S.; ヒハラ, タケヒコ; スミヤマ, ケンジ; 日原, 岳彦; 隅山, 兼治; Hihara, T.; Sumiyama, K.

    1999-01-01

    Magnetic properties have been measured for monodisperse-sized Co/CoO cluster assemblies prepared by a plasma-gas-condensation-type cluster beam deposition technique. The clear correlation obtained between exchange bias field and coercivity suggests the enhancement of uniaxial anisotropy owing to the exchange coupling between the ferromagnetic Co core and antiferromagnetic CoO shell, and magnetic disorder at the core-shell interface. A nonthermal magnetic relaxation observed below 8 K, being r...

  11. Aqueous dispersion of monodisperse magnetic iron oxide nanocrystals through phase transfer

    Energy Technology Data Exchange (ETDEWEB)

    Yu, William W [Department of Chemistry, Rice University, Houston, TX 77005 (United States); Chang, Emmanuel [Department of Bioengineering, Rice University, Houston, TX 77005 (United States); Sayes, Christie M [Department of Chemistry, Rice University, Houston, TX 77005 (United States); Drezek, Rebekah [Department of Bioengineering, Rice University, Houston, TX 77005 (United States); Colvin, Vicki L [Department of Chemistry, Rice University, Houston, TX 77005 (United States)

    2006-09-14

    A facile method was developed for completely transferring high quality monodisperse iron oxide nanocrystals from organic solvents to water. The as-prepared aqueous dispersions of iron oxide nanocrystals were extremely stable and could be functionalized for bioconjugation with biomolecules. These iron oxide nanocrystals showed negligible cytotoxicity to human breast cancer cells (SK-BR-3) and human dermal fibroblast cells. This method is general and versatile for many organic solvent-synthesized nanoparticles, including fluorescent semiconductor nanocrystals.

  12. Monodispersed bimetallic PdAg nanoparticles with twinned structures: Formation and enhancement for the methanol oxidation

    OpenAIRE

    Zhen Yin; Yining Zhang; Kai Chen; Jing Li; Wenjing Li; Pei Tang; Huabo Zhao; Qingjun Zhu; Xinhe Bao; Ding Ma

    2014-01-01

    Monodispersed bimetallic PdAg nanoparticles can be fabricated through the emulsion-assisted ethylene glycol (EG) ternary system. Different compositions of bimetallic PdAg nanoparticles, Pd80Ag20, Pd65Ag35 and Pd46Ag54 can be obtained via adjusting the reaction parameters. For the formation process of the bimetallic PdAg nanoparticles, there have two-stage growth processes: firstly, nucleation and growth of the primary nanoclusters; secondly, formation of the secondary nanoparticles with the s...

  13. In-site synthesis of monodisperse, oleylamine-capped Ag nanoparticles through microemulsion approach

    Science.gov (United States)

    Chen, Shun; Ju, Yanyun; Guo, Yi; Xiong, Chuanxi; Dong, Lijie

    2017-03-01

    Ag NPs were in-site synthesized through microemulsion method by reducing silver acetate with oleylamine-mediated at 70 °C with highly monodisperse and narrow size from 10 to 20 nm. The synthesis of Ag NPs was aided by oleylamine and the role of oleylamine was researched. This in-site synthesis approach to Ag NPs was reproducibility and high yield more than 80% with stable store about 6 months.

  14. One-pot polyol synthesis of highly monodisperse short green silver nanorods.

    Science.gov (United States)

    Patarroyo, Javier; Genç, Aziz; Arbiol, Jordi; Bastús, Neus G; Puntes, Victor

    2016-09-21

    Green silver nanorods (Ag NRs) of a low aspect ratio (2.8) have been produced in high yields via an optimized, simple, and robust one-pot polyol method in the presence of tannic acid, which favors the nucleation of decahedral seeds needed for the production of monodisperse Ag NRs. These Ag NRs were further used as sacrificial templates to produce Au hollow nanostructures via galvanic replacement reaction with HAuCl4 at room temperature.

  15. Effects of PVP on the preparation and growth mechanism of monodispersed Ni nanoparticles

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Monodispersed Ni nanoparticles were successfully prepared by chemical reduction with hydrazine hydrate in ethylene glycol.The effect of the amount of polyvinylpyrrolidone (PVP-K30) on the preparation of Ni nanoparticles was investigated.X-ray diffraction (XRD),transmission electron microscopy (TEM),and high resolution transmission electron microscopy (HRTEM) were employed to characterize the nickel particles are spherical in shape and are not agglomerated.A possible extensive mechanism of nickel nanoparticle formation has been suggested.

  16. Silaffins in Silica Biomineralization and Biomimetic Silica Precipitation

    Directory of Open Access Journals (Sweden)

    Carolin C. Lechner

    2015-08-01

    Full Text Available Biomineralization processes leading to complex solid structures of inorganic material in biological systems are constantly gaining attention in biotechnology and biomedical research. An outstanding example for biomineral morphogenesis is the formation of highly elaborate, nano-patterned silica shells by diatoms. Among the organic macromolecules that have been closely linked to the tightly controlled precipitation of silica in diatoms, silaffins play an extraordinary role. These peptides typically occur as complex posttranslationally modified variants and are directly involved in the silica deposition process in diatoms. However, even in vitro silaffin-based peptides alone, with and without posttranslational modifications, can efficiently mediate biomimetic silica precipitation leading to silica material with different properties as well as with encapsulated cargo molecules of a large size range. In this review, the biomineralization process of silica in diatoms is summarized with a specific focus on silaffins and their in vitro silica precipitation properties. Applications in the area of bio- and nanotechnology as well as in diagnostics and therapy are discussed.

  17. Studies on Monodispersed Microspheres of Zinc Sulfide Doped with Mn2+

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In this paper, zinc acetate, manganese acetate and thiacetamide are used as raw materials to successfully synthesize monodispersed ZnS:Mn2+ microspheres by using hydrothermal method and taking P123 surfactant as a template. The products were characterized by XRD, STEM,FT-IR and N2 adsorption-desorption. And the results show that the diameter of this microsphere is 1.0 μm or so, which is larger than that of ZnS microsphere without Mn2+ doping, and it has monodispersion, smooth surface and uniform size. The doping of Mn2+ does not obviously change the structure of monodispersed ZnS microsphere. The photoluminescence peak lies in a wide band ranging from 450 to 650 nm, and the microspheres emit orange light;with the increase of Mn2+concentration, fluorescence intensity of ZnS:Mn2+ microsphere changes, and when the mole ratio of Mn2+:Zn2+is 0.3:1, the fluorescence intensity is the strongest.

  18. Monodispersity of recombinant Cre recombinase correlates with its effectiveness in vivo

    Directory of Open Access Journals (Sweden)

    Edenhofer Frank

    2009-09-01

    Full Text Available Abstract Background Cre recombinase is a common reagent used for the in vivo on/off switching of the expression of target genes flanked by loxP sites. In particular, recombinant TAT-Cre fusion constructs purified from bacteria have been used to promote the cell uptake of the enzyme. However, the recovery of active TAT-Cre remains a demanding process and its specific activity varies significantly among batches, making difficult data comparison. Results We noticed a strong correlation between recombinase activity and enzyme monodispersity. The existence of such correlation enabled us to indirectly monitor the TAT-Cre recombinase activity during the multi-step purification process by measuring its monodispersity, a parameter detectable by means of a spectrofluorimetric assay that allows the calculation of the Aggregation Index (AI in an easy and rapid way. AI values were recorded after each purification passage to identify the critical steps and to choose optimal alternatives for chromatographic conditions, desalting procedures, and protocols for bacterial endotoxin removal. Furthermore, the effect of metal ions and temperature on TAT-Cre aggregation and inactivation was characterized in vitro. Finally, we optimized the enzyme delivery protocol in vivo by following the accumulation tuning of the reporter protein β-catenin. Conclusion A rational purification protocol for TAT-Cre has been developed by choosing the options that minimize the enzyme aggregation. Our data suggest that AI measurement should support the optimization of any protocol aiming at the recovery of monodispersed protein.

  19. Existence of isostatic, maximally random jammed monodisperse hard-disk packings.

    Science.gov (United States)

    Atkinson, Steven; Stillinger, Frank H; Torquato, Salvatore

    2014-12-30

    We generate jammed packings of monodisperse circular hard-disks in two dimensions using the Torquato-Jiao sequential linear programming algorithm. The packings display a wide diversity of packing fractions, average coordination numbers, and order as measured by standard scalar order metrics. This geometric-structure approach enables us to show the existence of relatively large maximally random jammed (MRJ) packings with exactly isostatic jammed backbones and a packing fraction (including rattlers) of [Formula: see text]. By contrast, the concept of random close packing (RCP) that identifies the most probable packings as the most disordered misleadingly identifies highly ordered disk packings as RCP in 2D. Fundamental structural descriptors such as the pair correlation function, structure factor, and Voronoi statistics show a strong contrast between the MRJ state and the typical hyperstatic, polycrystalline packings with [Formula: see text] that are more commonly obtained using standard packing protocols. Establishing that the MRJ state for monodisperse hard disks is isostatic and qualitatively distinct from commonly observed polycrystalline packings contradicts conventional wisdom that such a disordered, isostatic packing does not exist due to a lack of geometrical frustration and sheds light on the nature of disorder. This prompts the question of whether an algorithm may be designed that is strongly biased toward generating the monodisperse disk MRJ state.

  20. Synthesis of monodisperse silver nanoparticles for ink-jet printed flexible electronics

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Zhiliang; Zhang Xingye; Xin Zhiqing; Deng Mengmeng; Wen Yongqiang; Song Yanlin, E-mail: zhangxy@iccas.ac.cn, E-mail: ylsong@iccas.ac.cn [Beijing National Laboratory for Molecular Sciences (BNLMS), Key Lab of Organic Solids, Laboratory of New Materials, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China)

    2011-10-21

    In this study, monodisperse silver nanoparticles were synthesized with a new reduction system consisting of adipoyl hydrazide and dextrose at ambient temperature. By this facile and rapid approach, high concentration monodisperse silver nanoparticles were obtained on a large scale at low protectant/AgNO{sub 3} mass ratio which was highly beneficial to low cost and high conductivity. Based on the synthesized monodisperse silver nanoparticles, conductive inks were prepared with water, ethanol and ethylene glycol as solvents, and were expected to be more environmentally friendly. A series of electrocircuits were fabricated by ink-jet printing silver nanoparticle ink on paper substrate with a commercial printer, and they had low resistivity in the range of 9.18 x 10{sup -8}-8.76 x 10{sup -8} {Omega} m after thermal treatment at 160 {sup 0}C for 30 min, which was about five times that of bulk silver (1.586 x 10{sup -8} {Omega} m). Moreover, a radio frequency identification (RFID) antenna was fabricated by ink-jet printing, and 6 m wireless identification was realized after an Alien higgs-3 chip was mounted on the printed antenna by the flip-chip method. These flexible electrocircuits produced by ink-jet printing would have enormous potential for low cost electrodes and sensor devices.

  1. Synthesis of monodisperse silver nanoparticles for ink-jet printed flexible electronics.

    Science.gov (United States)

    Zhang, Zhiliang; Zhang, Xingye; Xin, Zhiqing; Deng, Mengmeng; Wen, Yongqiang; Song, Yanlin

    2011-10-21

    In this study, monodisperse silver nanoparticles were synthesized with a new reduction system consisting of adipoyl hydrazide and dextrose at ambient temperature. By this facile and rapid approach, high concentration monodisperse silver nanoparticles were obtained on a large scale at low protectant/AgNO(3) mass ratio which was highly beneficial to low cost and high conductivity. Based on the synthesized monodisperse silver nanoparticles, conductive inks were prepared with water, ethanol and ethylene glycol as solvents, and were expected to be more environmentally friendly. A series of electrocircuits were fabricated by ink-jet printing silver nanoparticle ink on paper substrate with a commercial printer, and they had low resistivity in the range of 9.18 × 10( - 8)-8.76 × 10( - 8) Ω m after thermal treatment at 160 °C for 30 min, which was about five times that of bulk silver (1.586 × 10( - 8) Ω m). Moreover, a radio frequency identification (RFID) antenna was fabricated by ink-jet printing, and 6 m wireless identification was realized after an Alien higgs-3 chip was mounted on the printed antenna by the flip-chip method. These flexible electrocircuits produced by ink-jet printing would have enormous potential for low cost electrodes and sensor devices.

  2. Synthesis of sulfonated porous carbon nanospheres solid acid by a facile chemical activation route

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Binbin, E-mail: changbinbin806@163.com; Guo, Yanzhen; Yin, Hang; Zhang, Shouren; Yang, Baocheng, E-mail: baochengyang@yahoo.com

    2015-01-15

    Generally, porous carbon nanospheres materials are usually prepared via a template method, which is a multi-steps and high-cost strategy. Here, we reported a porous carbon nanosphere solid acid with high surface area and superior porosity, as well as uniform nanospheical morphology, which prepared by a facile chemical activation with ZnCl{sub 2} using resorcinol-formaldehyde (RF) resins spheres as precursor. The activation of RF resins spheres by ZnCl{sub 2} at 400 °C brought high surface area and large volume, and simultaneously retained numerous oxygen-containing and hydrogen-containing groups due to the relatively low processing temperature. The presence of these functional groups is favorable for the modification of –SO{sub 3}H groups by a followed sulfonation treating with sulphuric acid and organic sulfonic acid. The results of N{sub 2} adsorption–desorption and electron microscopy clearly showed the preservation of porous structure and nanospherical morphology. Infrared spectra certified the variation of surface functional groups after activation and the successful modification of –SO{sub 3}H groups after sulfonation. The acidities of catalysts were estimated by an indirect titration method and the modified amount of –SO{sub 3}H groups were examined by energy dispersive spectra. The results suggested sulfonated porous carbon nanospheres catalysts possessed high acidities and –SO{sub 3}H densities, which endowed their significantly catalytic activities for biodiesel production. Furthermore, their excellent stability and recycling property were also demonstrated by five consecutive cycles. - Graphical abstract: Sulfonated porous carbon nanospheres with high surface area and superior catalytic performance were prepared by a facile chemical activation route. - Highlights: • Porous carbon spheres solid acid prepared by a facile chemical activation. • It owns high surface area, superior porosity and uniform spherical morphology. • It possesses

  3. Co-operative mineralization and protein self-assembly in amelogenesis: silica mineralization and assembly of recombinant amelogenins in vitro.

    Science.gov (United States)

    Fowler, Christabel E; Beniash, Elia; Yamakoshi, Yasuo; Simmer, James P; Margolis, Henry C

    2006-05-01

    An amorphous silica mineralization technique was used to produce inorganic/protein composites to elucidate the structure and mechanism of formation of amelogenin assemblies, which may play an important role in regulating enamel structure during the initial stages of amelogenesis. Full-length recombinant amelogenins from mouse (rM179) and pig (rP172) were investigated along with key degradation products (rM166 and native P148) lacking the hydrophilic C terminus found in parent molecules. The resulting products were examined using transmission electron microscopy and/or small-angle X-ray scattering. Using protein concentrations of 0.1-3 mg ml-1, large monodisperse spheres of remarkably similar mean diameters were observed using rM179 (124+/-4 nm) and rP172 (126+/-7 nm). These spheres also exhibited 'internal structure', comprising nearly spherical monodisperse particles of approximately 20 nm in diameter. In the presence of rM166, P148, and bovine serum albumin (control), large unstructured and randomly shaped particles (250-1000 nm) were observed. Without added protein, large dense spherical particles of silica (mean approximately 500 nm) lacking internal structure were produced. These findings demonstrate that full-length amelogenins have the ability to form higher-order structures, whereas amelogenins that lack the hydrophilic C terminus do not. The results also suggest that full-length amelogenin can guide the formation of organized mineralized structures through co-operative interactions between assembling protein and forming mineral.

  4. Gradual growth of gold nanoseeds on silica for SiO2@gold homogeneous nano core/shell applications by the chemical reduction method

    Science.gov (United States)

    Rezvani Nikabadi, H.; Shahtahmasebi, N.; Rezaee Rokn-Abadi, M.; Bagheri Mohagheghi, M. M.; Goharshadi, E. K.

    2013-02-01

    In this paper, a facile method for the synthesis of gold nanoseeds on the functionalized surface of silica nanoparticles has been investigated. Mono-dispersed silica particles and gold nanoparticles were prepared by the chemical reduction method. The thickness of the Au shell was well controlled by repeating the reduction time of HAuCl4 on silica/3-aminopropyltriethoxysilane (APTES)/initial gold nanoparticles. The prepared SiO2@gold core/shell nanoparticles were studied using x-ray diffraction, scanning electron microscopy, transmission electron microscopy (TEM), Fourier transform infrared spectroscopy and ultraviolet visible (UV-Vis) spectroscopy. The TEM images indicated that the silica nanoparticles were spherical in shape with 100 nm diameters and functionalizing silica nanoparticles with a layer of bi-functional APTES molecules and tetrakis hydroxy methyl phosphonium chloride. The gold nanoparticles show a narrow size of up to 5 nm and by growing gold nanoseeds over the silica cores a red shift in the maximum absorbance of UV-Vis spectroscopy from 524 to 637 nm was observed.

  5. Biogenic nanostructured silica

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Silicon is by far the most abundant element in the earth crust and also is an essential element for higher plants, yet its biology and mechanisms in plant tolerance of biotic and abiotic stresses are poorly understood. Based on the molecular mechanisms of the biosilicification in marine organisms such as diatoms and sponges, the cell wall template-mediated self-assembly of nanostructured silica in marine organisms and higher plants as well as the related organic molecules are discussed. Understanding of the templating and structure-directed effects of silicon-processing organic molecules not only offers the clue for synthesizing silicon-based materials, but also helps to recognize the anomaly of silicon in plant biology.

  6. Electrochemical durability of heat-treated carbon nanospheres as catalyst supports for proton exchange membrane fuel cells.

    Science.gov (United States)

    Lv, Haifeng; Wu, Peng; Wan, Wei; Mu, Shichun

    2014-09-01

    Carbon nanospheres is wildly used to support noble metal nanocatalysts in proton exchange membrane (PEM) fuel cells, however they show a low resistance to electrochemical corrosion. In this study, the N-doped treatment of carbon nanospheres (Vulcan XC-72) is carried out in ammonia gas. The effect of heating treatment (up to 1000 degrees C) on resistances to electrochemical oxidation of the N-doped carbon nanospheres (HNC) is investigated. The resistance to electrochemical oxidation of carbon supports and stability of the catalysts are investigated with potentiostatic oxidation and accelerated durability test by simulating PEM fuel cell environment. The HNC exhibit a higher resistance to electrochemical oxidation than traditional Vulcan XC-72. The results show that the N-doped carbon nanospheres have a great potential application in PEM fuel cells.

  7. Polaritonic-to-Plasmonic Transition in Optically Resonant Bismuth Nanospheres for High-Contrast Switchable Ultraviolet Meta-Filters

    CERN Document Server

    Cuadrado, Alexander; Serna, Rosalia

    2015-01-01

    In the quest aimed at unveiling alternative plasmonic elements overcoming noble metals for selected applications in photonics, we investigate by numerical simulations the near ultraviolet-to-near infrared optical response of solid and liquid Bi nanospheres embedded in a dielectric matrix. We also determine the resulting transmission contrast upon reversible solid-liquid phase transition to evaluate their potential for switchable optical filtering. The optical response of the solid (liquid) Bi nanospheres is ruled by localized polaritonic (plasmonic) resonances tunable by controlling the diameter. For a selected diameter between 20 nm and 50 nm, both solid and liquid nanospheres present a dipolar resonance inducing a strong peak extinction in the near ultraviolet, however at different photon energies. This enables a high transmission contrast at selected near ultraviolet photon energies. It is estimated that a two-dimensional assembly of 20 nm solid Bi nanospheres with a surface coverage of 28% will totally ex...

  8. Radiolytic syntheses of hollow UO{sub 2} nanospheres in Triton X-100-based lyotropic liquid crystals

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yongming; Chen, Qingde; Shen, Xinghai [Peking Univ., Beijing (China). Fundamental Science on Radiochemistry and Radiation Chemistry Lab.

    2017-08-01

    Hollow nanospheres (φ: 60-80 nm, wall thickness: 10-20 nm), consisted of UO{sub 2} nanoparticles (φ: 3-5 nm), were successfully prepared in a Triton X-100-water (50:50, w/w) hexagonal lyotropic liquid crystal (LLC) by γ-irradiation, where water soluble ammonium uranyl tricarbonate was added as precursor. The product was stable at least up to 300 C. Furthermore, whether the nanospheres were hollow or not, and the wall thickness of the hollow nanospheres could be easily controlled via adjusting dose rate. While in the Triton X-100 based micellar systems, only solid nanospheres were obtained. At last, a possible combination mechanism containing adsorption, aggregation and fracturing processes was proposed.

  9. Hollow raspberry-like PdAg alloy nanospheres: High electrocatalytic activity for ethanol oxidation in alkaline media

    Science.gov (United States)

    Peng, Cheng; Hu, Yongli; Liu, Mingrui; Zheng, Yixiong

    2015-03-01

    Palladium-silver (PdAg) alloy nanospheres with unique structure were prepared using a one-pot procedure based on the galvanic replacement reaction. Their electrocatalytic activity for ethanol oxidation in alkaline media was evaluated. The morphology and crystal structure of the samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). Electrochemical characterization techniques, including cyclic voltammetry (CV) and chronoamperometry (CA) measurements were used to analyze the electrochemical performance of the PdAg alloy nanospheres. The SEM and TEM images showed that the PdAg alloy nanospheres exhibit a hierarchical nanostructure with hollow interiors and porous walls. Compared to the commercial Pd/C catalyst, the as-prepared PdAg alloy nanospheres exhibit superior electrocatalytic activity and stability towards ethanol electro-oxidation in alkaline media, showing its potential as a new non-Pt electro-catalyst for direct alcohol fuel cells (DAFCs).

  10. Synthesis of silica nanoparticles for the manufacture of porous carbon membrane and particle size analysis by sedimentation field-flow fractionation

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Seung Ho; Eum, Chul; Hun; Choi, Seong Ho; Kim, Woon Jung [Dept. of Chemistry, Hannam University, Daejeon (Korea, Republic of)

    2016-11-15

    Silica nanoparticles were synthesized by emulsion polymerization by mixing ethanol, ammonium hydroxide, water, and tetraethyl orthosilicate. An apparatus was designed and assembled for a large-scale synthesis of silica nanospheres, which was aimed for uniform mixing of the reactants. Then sedimentation field-flow fractionation (SdFFF) was used to determine the size distribution of the silica nanoparticles. SdFFF provided mass-based separation where the retention time increased with the particle size, thus the size distribution of silica nanoparticles obtained from SdFFF appeared more accurate than that from dynamic light scattering, particularly for those having broad and multimodal size distributions. A disk-shaped porous carbon membrane (PCM) was manufactured for application as an adsorbent by pressurizing the silica particles, followed by calcination. Results showed that PCM manufactured in this study has relatively high surface area and temperature stability. The PCM surface was modified by attaching a carboxyl group (PCM-COOH) and then by incorporating silver (PCM-COOH-Ag). The amount of COOH group on PCM was measured electrochemically by cyclic voltammetry, and the surface area, pore size, pore volume of PCM-COOH-Ag by Brunauer–Emmet–Teller measurement. The surface area was 40.65 and reduced to 13.02 after loading a COOH group then increased up to 30.37 after incorporating Ag.

  11. Enhancement of light harvesting efficiency of silicon solar cell utilizing arrays of poly(methyl methacrylate-co-acrylic acid) nano-spheres and nano-spheres with embedded silver nano-particles

    Science.gov (United States)

    Lee, Chee-Leong; Goh, Wee-Sheng; Chee, Swee-Yong; Yik, Lai-Kuan

    2017-02-01

    An array of uniformly distributed monolayer of poly(methyl methacrylate-co-acrylic acid) nano-spheres were deposited onto an amorphous silicon photovoltaic cell utilizing dip coating technique. The electrical characteristics of the coated photovoltaic cell reveal that the nano-spheres with an average diameter size of 101 nm exhibits excellent light harvesting characteristics if compared to the nano-spheres of other sizes. The power conversion efficiency from such integration of the nano-structures (i.e. 3.14% per PV cell) indicates that at least 1.6 times of improvement (or relative enhancement of 57%) can be achieved comparatively to the uncoated photovoltaic cell (i.e. 2% per PV cell). Further increment of the power conversion efficiency of the solar cell has been attained with the incorporation of the silver nano-particles into the nano-spheres of similar average size. With the inclusion of the silver nano-particles into such nano-spheres, the power conversion efficiency of the solar cell has attained 5.57% per PV cell, which is about 2.8 times (or relative enhancement of 179%) if compared to the uncoated samples. Hence, this novel and controllable technique of fabricating omnidirectional light-harvesting nano-spheres with embedded silver nano-particles will indubitably be beneficial to various types of optoelectronic devices.

  12. Silica nanoparticles on front glass for efficiency enhancement in superstrate-type amorphous silicon solar cells

    Science.gov (United States)

    Das, Sonali; Banerjee, Chandan; Kundu, Avra; Dey, Prasenjit; Saha, Hiranmay; Datta, Swapan K.

    2013-10-01

    Antireflective coating on front glass of superstrate-type single junction amorphous silicon solar cells (SCs) has been applied using highly monodispersed and stable silica nanoparticles (NPs). The silica NPs having 300 nm diameter were synthesized by Stober technique where the size of the NPs was controlled by varying the alcohol medium. The synthesized silica NPs were analysed by dynamic light scattering technique and Fourier transform infrared spectroscopy. The NPs were spin coated on glass side of fluorinated tin oxide (SnO2: F) coated glass superstrate and optimization of the concentration of the colloidal solution, spin speed and number of coated layers was done to achieve minimum reflection characteristics. An estimation of the distribution of the NPs for different optimization parameters has been done using field-emission scanning electron microscopy. Subsequently, the transparent conducting oxide coated glass with the layer having the minimum reflectance is used for fabrication of amorphous silicon SC. Electrical analysis of the fabricated cell indicates an improvement of 6.5% in short-circuit current density from a reference of 12.40 mA cm-2 while the open circuit voltage and the fill factor remains unaltered. A realistic optical model has also been proposed to gain an insight into the system.

  13. Impact of Amorphous Silica Nanoparticles on a Living Organism: Morphological, Behavioural and Molecular Biology Implications.

    Directory of Open Access Journals (Sweden)

    Alfredo eAmbrosone

    2014-09-01

    Full Text Available It is generally accepted that silica (SiO2 is not toxic. But the increasing use of silica nanoparticles (SiO2NPs in many different industrial fields has prompted the careful investigation of its toxicity in biological systems. In this report, we describe the effects elicited by SiO2NPs on animal and cell physiology. Stable and monodisperse amorphous silica nanoparticles 25nm in diameter, were administered to living Hydra vulgaris (Cnidaria. The dose-related effects were defined by morphological and behavioural assays. The results revealed an all-or-nothing lethal toxicity with a rather high threshold (35nM NPs and a LT50 of 38h. At sub lethal doses the morpho-physiological effects included: animal morphology alterations, paralysis of the gastric region, disorganization and depletion of tentacle specialized cells, increase of apoptotic and collapsed cells and reduction of the epithelial cell proliferation rate. Transcriptome analysis (RNAseq revealed 45 differentially expressed genes, mostly involved in stress response and cuticle renovation. Our results show that Hydra reacts to SiO2NPs, is able to rebalance the animal homeostasis up to a relatively high doses of SiO2NPs and that the physiological modifications are transduced to gene expression modulation.

  14. Morphological Control of Multifunctional Mesoporous Silica Nanomaterials for Catalysis Applications

    Energy Technology Data Exchange (ETDEWEB)

    Huh, Seong [Iowa State Univ., Ames, IA (United States)

    2004-12-19

    I found an efficient method to control the morphology of the organically monofunctionalized mesoporous silica materials by introducing different types of organoalkoxysilanes in a base-catalyzed co-condensation reaction. The monofunctionalized materials exhibit different particle morphologies relative to the pure MCM-41 material. The concentration dependence of the morphology is a critical factor to determine the final particle shape. A proposed mechanism of the shape evolution is also offered. After understanding the role of organoalkoxysilanes in producing various well-shaped nanomaterials, I also obtained a series of bifunctional mesoporous silica materials with certain particle morphology. A series of bifunctional mesoporous silica nanospheres (MSNs) whose physicochemical properties was investigated via solid state NMR techniques and Cu2+ adsorption capacity tests, The ratio of two different organic groups inside of mesopores of these MSNs could be fine-tuned. These MSNs serve as a useful model system to study substrate selectivity in catalytic reactions and sorption phenomena. For example, the Cu2+ adsorption capacity of these materials was dictated by the chemical nature of the mesopores generated by the different organic functional groups. An investigation of the substrate selectivity of the bifunctionalized MSNs in a competitive nitroaldol reaction using an equimolar amount of two competing 4-nitrobenzaldehyde derivatives was performed. Shape-controlled bifunctional MSNs were employed as the catalysts. The properties of the MSNs were investigated using various spectroscopic methods and electron microscopy. The more hydrophobic the surface organic groups are, the higher the ratio of hydrophobic final product. This is the first example to demonstrate the selection of substrate using physicochemical nature of the mesopore surface other than the conventional shape selection in zeolite systems. I also created a cooperative dual catalyst

  15. 21 CFR 582.1711 - Silica aerogel.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Silica aerogel. 582.1711 Section 582.1711 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1711 Silica aerogel. (a) Product. Silica aerogel as a finely powdered microcellular silica foam...

  16. 21 CFR 182.1711 - Silica aerogel.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Silica aerogel. 182.1711 Section 182.1711 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN....1711 Silica aerogel. (a) Product. Silica aerogel as a finely powdered microcellular silica foam...

  17. 21 CFR 584.700 - Hydrophobic silicas.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Hydrophobic silicas. 584.700 Section 584.700 Food... DRINKING WATER OF ANIMALS Listing of Specific Substances Affirmed as GRAS § 584.700 Hydrophobic silicas. (a) Product. Amorphous fumed hydrophobic silica or precipitated hydrophobic silica (CAS Reg. No....

  18. A Multimodal System with Synergistic Effects of Magneto-Mechanical, Photothermal, Photodynamic and Chemo Therapies of Cancer in Graphene-Quantum Dot-Coated Hollow Magnetic Nanospheres.

    Science.gov (United States)

    Wo, Fangjie; Xu, Rujiao; Shao, Yuxiang; Zhang, Zheyu; Chu, Maoquan; Shi, Donglu; Liu, Shupeng

    2016-01-01

    In this study, a multimodal therapeutic system was shown to be much more lethal in cancer cell killing compared to a single means of nano therapy, be it photothermal or photodynamic. Hollow magnetic nanospheres (HMNSs) were designed and synthesized for the synergistic effects of both magneto-mechanical and photothermal cancer therapy. By these combined stimuli, the cancer cells were structurally and physically destroyed with the morphological characteristics distinctively different from those by other therapeutics. HMNSs were also coated with the silica shells and conjugated with carboxylated graphene quantum dots (GQDs) as a core-shell composite: HMNS/SiO2/GQDs. The composite was further loaded with an anticancer drug doxorubicin (DOX) and stabilized with liposomes. The multimodal system was able to kill cancer cells with four different therapeutic mechanisms in a synergetic and multilateral fashion, namely, the magnetic field-mediated mechanical stimulation, photothermal damage, photodynamic toxicity, and chemotherapy. The unique nanocomposites with combined mechanical, chemo, and physical effects will provide an alternative strategy for highly improved cancer therapy efficiency.

  19. The construction, characterization, Hg(II)-sensing and removal behavior of magnetic core-shell nanospheres loaded with fluorescence "Off-On" probe.

    Science.gov (United States)

    Tan, Jun; Wei, Xiaoyan; Chen, Jie; Sun, Ping; Ouyang, Yuxia; Fan, Juhong; Liu, Rui

    2014-12-10

    The present paper constructed and discussed core-shell structured nanospheres grafted with rhodamine based probe for Hg(II) sensing and removal. Electron microscopy images, XRD curves, thermogravimetric analysis and N2 adsorption/desorption isotherms were used to identify the core-shell structure. The inner core consisted of superparamagnetic Fe3O4 nanoparticles, which made the nanocomposite magnetically removable. The outer shell was constructed with silica molecular sieve which provided large surface area and ordered tunnels for the sensing probe, accelerating analyte adsorption and transportation. The rhodamine based sensing probe emission increased with the increasing Hg(II) concentration, showing emission "Off-On" effect, which could be explained by the structural transformation from a non-emissive one to a highly emissive one. The influence from various metal ions and pH values was also investigated, which suggested this structural transformation could only be triggered by Hg(II), showing high selectivity and linear response. The Hg(II) sensing nanocomposite could be regenerated after usage. The response time was slightly compromised and could be further improved.

  20. Size-tunable fabrication of multifunctional Bi2O3 porous nanospheres for photocatalysis, bacteria inactivation and template-synthesis.

    Science.gov (United States)

    Qin, Fan; Zhao, Huiping; Li, Guangfang; Yang, Hao; Li, Ju; Wang, Runming; Liu, Yunling; Hu, Juncheng; Sun, Hongzhe; Chen, Rong

    2014-05-21

    Multifunctional Bi2O3 porous nanospheres (PNs) with tunable size have been successfully synthesized via a facile solvothermal method. The obtained Bi2O3 porous nanospheres demonstrate outstanding performance in visible-light-driven photocatalysis for Cr(VI) and organic dye removal, inactivation of Gram-negative and Gram-positive bacteria, as well as template-synthesis for fabrication of bismuth-related hollow nanostructures.