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Synthetic colloid

Dayeon Choi, Ji-Young Pyo, Du-Jeon Jang
Various types of 2% Cu-incorporated CdS (Cu:CdS) quantum dots (QDs) with very similar sizes have been prepared via a water soluble colloidal method. The locations of Cu impurities in CdS host nanocrystals have been controlled by adopting three different synthetic ways of doping, exchange, and adsorption to understand the impurity location-dependent relaxation dynamics of charge carriers. The oxidation state of incorporated Cu impurities has been found to be +1 and the band-gap energy of Cu:CdS QDs decreases as Cu2S forms at the surfaces of CdS QDs...
December 2017: Nanoscale Research Letters
Alison M Douglas, Alexandros A Fragkopoulos, Michelle K Gaines, L Andrew Lyon, Alberto Fernandez-Nieves, Thomas H Barker
In regenerative medicine, natural protein-based polymers offer enhanced endogenous bioactivity and potential for seamless integration with tissue, yet form weak hydrogels that lack the physical robustness required for surgical manipulation, making them difficult to apply in practice. The use of higher concentrations of protein, exogenous cross-linkers, and blending synthetic polymers has all been applied to form more mechanically robust networks. Each relies on generating a smaller network mesh size, which increases the elastic modulus and robustness, but critically inhibits cell spreading and migration, hampering tissue regeneration...
January 18, 2017: Proceedings of the National Academy of Sciences of the United States of America
Rustem Zairov, Asiya Mustafina, Nataliya Shamsutdinova, Irek Nizameev, Beatriz Moreira, Svetlana Sudakova, Sergey Podyachev, Alfia Fattakhova, Gulnara Safina, Ingemar Lundstrom, Aidar Gubaidullin, Alberto Vomiero
Polyelectrolyte-coated nanoparticles consisting of terbium and gadolinium complexes with calix[4]arene tetra-diketone ligand were first synthesized. The antenna effect of the ligand on Tb(III) green luminescence and the presence of water molecules in the coordination sphere of Gd(III) bring strong luminescent and magnetic performance to the core-shell nanoparticles. The size and the core-shell morphology of the colloids were studied using transmission electron microscopy and dynamic light scattering. The correlation between photophysical and magnetic properties of the nanoparticles and their core composition was highlighted...
January 16, 2017: Scientific Reports
Marko Pavlovic, Paul Rouster, Elodie Bourgeat-Lami, Vanessa Prevot, Istvan Szilagyi
Colloidal stability of polymeric latex particles was studied in the presence of oppositely charged layered double hydroxide (LDH) platelets of different interlayer anions. Adsorption of the LDH particles led to charge neutralization and to overcharging of the latex at appropriate concentrations. Mixing stable colloidal suspensions of individual particles results in rapid aggregation once the LDH adsorption neutralizes the negative charges of the polymer spheres, while stable suspensions were observed at high and low LDH doses...
January 12, 2017: Soft Matter
Li Song, Tao Wang, Yilin Wang, Hairong Xue, Xiaoli Fan, Hu Guo, Wei Xia, Hao Gong, Jianping He
We synthesized a novel nonprecious metal electrocatalyst by pyrolysis of a colloid mixture consisting of a tungsten source and phenolic resin, with the simultaneous addition of ferric salt. The rationally designed electrocatalyst has a unique structure, with nanosized WC and Fe3W3C uniformly dispersed in a three-dimensional porous carbon framework. WC, which was thought difficult to produce, is successfully prepared at a relatively low temperature of about 750 °C at an inert atmosphere. XRD studies demonstrate the self-assisted effect of Fe, which accelerates the formation of WC, getting around the pathway of direct carbonaceous reduction of tungsten by carbon...
January 18, 2017: ACS Applied Materials & Interfaces
Natalia Mordvinova, Alexander Vinokurov, Tatiana Kuznetsova, Oleg I Lebedev, Sergey Dorofeev
Here we report a simple method for the creation of highly luminescent core-shell InP/ZnX (X = S, Se) quantum dots (QDs) on the basis of a phosphine synthetic route. In this method a Zn precursor was added to the reaction mixture at the beginning of the synthesis to form an In(Zn)P alloy structure, which promoted the formation of a ZnX shell. Core-shell InP/ZnX QDs exhibit highly intensive emission with a quantum yield over 50%. The proposed method is primarily important for practical applications. Advantages of this method compared to the widely used SILAR technique are discussed...
January 9, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Liuen Liang, Yiqing Lu, Run Zhang, Andrew Care, Tiago A Ortega, Sergey M Deyev, Yi Qian, Andrei V Zvyagin
: The fluorescent protein KillerRed, a new type of biological photosensitizer, is considered as a promising substitute for current synthetic photosensitizes used in photodynamic therapy (PDT). However, broad applications of this photosensitiser in treating deep-seated lesions is challenging due to the limited tissue penetration of the excitation light with the wavelength falling in the visible spectral range. To overcome this challenge, we employ upconversion nanoparticles (UCNPs) that are able to convert deep-penetrating near infrared (NIR) light to green light to excite KillerRed locally, followed by the generation of reactive oxygen species (ROS) to kill tumour cells under centimetre-thick tissue...
January 4, 2017: Acta Biomaterialia
Wenxiu Hou, Fangfang Xia, Gabriel Alfranca, Hao Yan, Xiao Zhi, Yanlei Liu, Chen Peng, Chunlei Zhang, Jesus Martinez de la Fuente, Daxiang Cui
It is essential to develop a simple synthetic strategy to improve the quality of multifunctional contrast agents for cancer diagnosis. Herein, we report a time-saving method for gadolinium (Gd(3+)) ions-mediated self-assembly of gold nanoclusters (GNCs) into monodisperse spherical nanoparticles (GNCNs) under mild conditions. The monodisperse, regular and colloidal stable GNCNs were formed via selectively inducing electrostatic interactions between negatively-charged carboxylic groups of gold nanoclusters and trivalent cations of gadolinium in aqueous solution...
December 27, 2016: Biomaterials
Jamila Djafari, Catarina Marinho, Tiago Santos, Gilberto Igrejas, Carmen Torres, José Luis Capelo, Patricia Poeta, Carlos Lodeiro, Javier Fernández-Lodeiro
The Front Cover picture shows new silver (Ag) and gold (Au) nanoparticle-based tetracycline (TC) nanocomposites (AuNPs@TC and AgNPs@TC). A new synthetic methodology for the preparation of water-soluble Au and Ag nanoparticles, using the antibiotic TC as co-reducing and stabilizing agent, is reported. Both colloids exhibit high water stability, with an average size of 15±5 and 25±10 nm, respectively. Both composites are tested against TC-resistant bacteria, presenting an increasing antibacterial effect in the case of AgNPs@TC...
June 2016: ChemistryOpen
Youngjin Jang, Arthur Shapiro, Maya Isarov, Anna Rubin-Brusilovski, Aron Safran, Adam K Budniak, Faris Horani, Joanna Dehnel, Aldona Sashchiuk, Efrat Lifshitz
Semiconductor colloidal quantum dots (CQDs) have attracted vast scientific and technological interest throughout the past three decades, due to the unique tuneability of their optoelectronic properties by variation of size and composition. However, the nanoscale size brings about a large surface-to-bulk volume ratio, where exterior surfaces have a pronounced influence on the chemical stability and on the physical properties of the semiconductor. Therefore, numerous approaches have been developed to gain efficient surface passivation, including a coverage by organic or inorganic molecular surfactants as well as the formation of core/shell heterostructures (a semiconductor core epitaxially covered by another semiconductor shell)...
December 20, 2016: Chemical Communications: Chem Comm
Taiyo Shimizu, Kazuyoshi Kanamori, Ayaka Maeno, Hironori Kaji, Kazuki Nakanishi
Transparent, monolithic aerogels with nanosized colloidal skeletons have been obtained from a single precursor of 1,2-bis(methyldiethoxysilyl)ethane (BMDEE) by adopting a liquid surfactant and a two-step process involving strong-acid, followed by strong-base, sol-gel reactions. This precursor BMDEE forms the ethylene-bridged polymethylsiloxane (EBPMS, O2/2(CH3)Si-CH2CH2-Si(CH3)O2/2) network, in which each silicon has one methyl, two bridging oxygens, and one bridging ethylene, exhibiting an analogous structure to that of the previously reported polymethylsilsesquioxane (PMSQ, CH3SiO3/2) aerogels having one methyl and three bridging oxygen atoms...
December 20, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Ben Liu, Lei Jin, Haoquan Zheng, Huiqin Yao, Yang Wu, Aaron Lopes, Jie He
A general synthetic methodology is reported to grow ultrafine cobalt-based nanoparticles (NPs, 2-7 nm) within high-surface-area mesoporous carbon (MC) frameworks. Our design strategy is based on colloidal amphiphile (CAM) templated oxidative self-polymerization of dopamine. The CAM templates consisting of a hydrophobic silica-like core and a hydrophilic PEO shell can coassemble with dopamine and template its self-polymerization to form polydopamine (PDA) nanospheres. Given that PDA has rich binding sites such as catechol and amine to coordinate metal ions (e...
January 18, 2017: ACS Applied Materials & Interfaces
Zhichao Zhu, Junfeng Xiang, Jianjun Wang, Dong Qiu
Tuning ice formation is of great importance in biological systems and some technological applications. Many synthetic polymers have been shown to affect ice formation, in particular, polyvinyl alcohol (PVA). However, the experimental observations of the effect of PVA on ice formation are still conflicting. Here, we introduced colloidal silica (CS) as the model liquid/solid interface and studied the effect of PVA on ice formation in detail. The results showed that either PVA or CS promoted ice formation, whereas the mixture of these two (CS-PVA) prevented ice formation (antifreezing)...
December 19, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Raihana Begum, Manas R Parida, Ahmed L Abdelhady, Banavoth Murali, Noktan M Alyami, Ghada H Ahmed, Mohamed Nejib Hedhili, Osman M Bakr, Omar F Mohammed
Since compelling device efficiencies of perovskite solar cells have been achieved, investigative efforts have turned to understand other key challenges in these systems, such as engineering interfacial energy-level alignment and charge transfer (CT). However, these types of studies on perovskite thin-film devices are impeded by the morphological and compositional heterogeneity of the films and their ill-defined surfaces. Here, we use well-defined ligand-protected perovskite nanocrystals (NCs) as model systems to elucidate the role of heterovalent doping on charge-carrier dynamics and energy level alignment at the interface of perovskite NCs with molecular acceptors...
January 18, 2017: Journal of the American Chemical Society
Joong Pill Park, Jae-Joon Lee, Sang-Wook Kim
We first report the GaAs/ZnSe and InxGa1-xAs/ZnSe core/shell structured colloidal quantum dots (CQDs). GaAs based CQD, which are hard to obtain by the chemical synthetic method, can be prepared successfully using the acetylacetonate complex of indium and gallium as cationic precursors. We control the indium contents, and the photoluminescence emission is tuned from orange to deep red. In0.2Ga0.8As/ZnSe core/shell QDs show the best quantum yield of 25.6%. A ZnSe outer shell protects the core and improves quantum yield, and it shows a large red shift owing to the quasi-type-I band structure...
December 28, 2016: Journal of the American Chemical Society
Aimee Brooks, Elizabeth Thomovsky, Paula Johnson
This review article covers basic physiology underlying the clinical use of natural and artificial colloids as well as provide practice recommendations. It also touches on the recent scrutiny of these products in human medicine and how this may have an effect on their use in veterinary medicine.
June 2016: Topics in Companion Animal Medicine
Jamila Djafari, Catarina Marinho, Tiago Santos, Gilberto Igrejas, Carmen Torres, José Luis Capelo, Patricia Poeta, Carlos Lodeiro, Javier Fernández-Lodeiro
A new synthetic methodology of water-soluble gold and silver nanoparticles (AuNPs@TC and AgNPs@TC), using the antibiotic tetracycline (TC) as co-reducing and stabilizing agent, is reported. Both colloids exhibit high water stability. The average sizes obtained were 25±10 and 15±5 nm, respectively. Both composites were tested against TC-resistant bacteria, presenting an increasing antibacterial effect in the case of AgNPs@TC. The sensing towards metal ions was also explored. An interesting and reversible affinity of AuNPs@TC towards Al(III) cations in an aqueous system was also observed...
June 2016: ChemistryOpen
H Samet Varol, Olaia Álvarez-Bermúdez, Paolo Dolcet, Balati Kuerbanjiang, Silvia Gross, Katharina Landfester, Rafael Muñoz-Espí
A heterophase method to prepare hollow and/or porous crystalline nanoparticles of metal oxides at room temperature is presented, taking cerium(IV) oxide and γ-iron(III) oxide (i.e., maghemite) as representative cases. The crystallization begins at the oil-water interface in aqueous nanodroplets of the precursor in inverse (water-in-oil) miniemulsion systems, and it may continue toward the inner part of the droplets. A poly(styrene-b-acrylic acid) block copolymer is used as a structuring agent because the ability of the carboxylic groups to bind metal ions improves the inorganic shell formation...
December 13, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Yi Shen, Megan Y Gee, A B Greytak
Almost all applications of colloidal nanocrystals require some type of purification or surface modification process following nanocrystal growth. Nanocrystal purification - the separation of nanocrystals from undesired solution components - can perturb the surface chemistry and thereby the physical properties of colloidal nanocrystals due to changes in solvent, solute concentrations, and exposure of the nanocrystal surface to oxidation or hydrolysis. For example, nanocrystal quantum dots frequently exhibit decreased photoluminescence brightness after precipitation from the growth solvent and subsequent redissolution...
December 12, 2016: Chemical Communications: Chem Comm
Tom Kollek, Daniel Wurmbrand, Susanne T Birkhold, Eugen Zimmermann, Julian Kalb, Lukas Schmidt-Mende, Sebastian Polarz
Particle-based semiconductor materials are promising constituents of future technologies. They are described by unique features resulting from the combination of discrete nanoparticle characteristics and the emergence of cooperative phenomena based on long-range interaction within their superstructure. (Nano)particles of outstanding quality with regards to size and shape can be prepared via colloidal synthesis using appropriate capping agents. The classical capping agents are electrically insulating, which impedes particle-particle electronic communication...
December 20, 2016: ACS Applied Materials & Interfaces
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