scholarly journals Titanium dioxide/silver nanoparticle bilayers prepared in self-assembly processes

2016 ◽  
Vol 71 (1) ◽  
pp. 29
Author(s):  
Julia Maciejewska ◽  
Magdalena Oćwieja ◽  
Zbigniew Adamczyk ◽  
Elżbieta Bielańska ◽  
Bogna Napruszewska
Keyword(s):  
Silver Nanoparticles ◽  
Titanium Dioxide ◽  
Ionic Strength ◽  
Silver Nanoparticle ◽  
Self Assembly ◽  
Electrostatic Interactions ◽  
Titanium Dioxide Nanoparticles ◽  
Chemical Reduction ◽  
Supporting Layer ◽  
Phosphate Salts

<p>A new method for the preparation of TiO<sub>2</sub>/Ag bilayers via colloid <br /> self-assembly process using well-characterized titanium dioxide and silver suspensions was developed. The titanium dioxide nanoparticles, forming a supporting layer, were 46 nm in diameter, exhibiting an isoelectric point at pH 6.4. The silver nanoparticles, forming an external layer of the diameter of 50 nm were prepared via a chemical reduction method with the presence inorganic phosphate salts. The electrophoretic mobility measurements revealed that the zeta potential of silver nanoparticles was highly negative for a broad range of pH and ionic strengths. By explaining this information, the optimum condition for the silver nanoparticle immobilization on TiO<sub>2</sub> supporting layers were selected. The coverage of the first layer was adjusted by ionic strength of the suspensions and by the deposition time. Afterward, the silver nanoparticle monolayers of controlled coverage were deposited under the diffusion-controlled transport. Their coverage was determined by a direct enumeration of deposited nanoparticles from AFM images and SEM micrographs. The experimental results showed that for extended deposition times, the coverage of silver nanoparticle layers significantly increases with ionic strength. Therefore, it was proven that the formation of bilayers is mainly controlled by electrostatic interactions and that it is feasible to produce uniform TiO<sub>2</sub>/Ag materials of desired coverage and structure.</p>

scholarly journals Titanium Dioxide Nanoparticles Elicit Lower Direct Inhibitory Effect on Human Gut Microbiota Than Silver Nanoparticles

2019 ◽  
Vol 172 (2) ◽  
pp. 411-416 ◽  
Author(s):  
Richard T Agans ◽  
Alex Gordon ◽  
Saber Hussain ◽  
Oleg Paliy
Keyword(s):  
Silver Nanoparticles ◽  
Titanium Dioxide ◽  
Gut Microbiota ◽  
Titanium Dioxide Nanoparticles ◽  
Close Association ◽  
Community Diversity ◽  
Bacterial Cells ◽  
Human Gut ◽  
Human Gut Microbiota

Abstract Due to continued technological development, people increasingly come in contact with engineered nanomaterials (ENMs) that are now used in foods and many industrial applications. Many ENMs have historically been shown to possess antimicrobial properties, which has sparked concern for how dietary nanomaterials impact gastrointestinal health via microbial dysbiosis. We employed an in vitro Human Gut Simulator system to examine interactions of dietary nano titanium dioxide (TiO2) with human gut microbiota. Electron microscopy indicated a close association of TiO2 particles with bacterial cells. Addition of TiO2 to microbial communities led to a modest reduction in community density but had no impact on community diversity and evenness. In contrast, administration of known antimicrobial silver nanoparticles (NPs) in a control experiment resulted in a drastic reduction of population density. In both cases, communities recovered once the addition of nanomaterials was ceased. Constrained ordination analysis of community profiles revealed that simulated colonic region was the primary determinant of microbiota composition. Accordingly, predicted community functional capacity and measured production of short-chain fatty acids were not changed significantly upon microbiota exposure to TiO2. We conclude that tested TiO2 NPs have limited direct effect on human gut microbiota.

Impacts of titanium dioxide nanoparticles on transformation of silver nanoparticles in aquatic environments

2018 ◽  
Vol 5 (5) ◽  
pp. 1191-1199 ◽  
Author(s):  
Yinqing Zhang ◽  
Liwen Qiang ◽  
Yuting Yuan ◽  
Wei Wu ◽  
Binbin Sun ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Titanium Dioxide ◽  
Titanium Dioxide Nanoparticles ◽  
Aquatic Environments ◽  
Oxidative Dissolution ◽  
Sunlight Irradiation

Under sunlight irradiation, titanium dioxide nanoparticles could promote the oxidative dissolution of silver nanoparticles in aquatic environments.

Influence of Ionic Strength, pH, and Cation Valence on Aggregation Kinetics of Titanium Dioxide Nanoparticles

2009 ◽  
Vol 43 (5) ◽  
pp. 1354-1359 ◽  
Author(s):  
Rebecca A. French ◽  
Astrid R. Jacobson ◽  
Bojeong Kim ◽  
Sara L. Isley ◽  
R. Lee Penn ◽  
...  
Keyword(s):  
Titanium Dioxide ◽  
Ionic Strength ◽  
Titanium Dioxide Nanoparticles ◽  
Aggregation Kinetics ◽  
Kinetics Of

Insight into the Mechanisms Driving the Self-Assembly of Functional Interfaces: Moving from Lipids to Charged Amphiphilic Oligomers

2019 ◽  
Author(s):  
Azhad U. Chowdhury ◽  
Graham J. Taylor ◽  
Vera Bocharova ◽  
Robert L. Sacci ◽  
Yingdong Luo ◽  
...  
Keyword(s):  
Ionic Strength ◽  
Aqueous Phase ◽  
Self Assembly ◽  
Electrostatic Interactions ◽  
Conformational Sampling ◽  
Fast Time ◽  
Sum Frequency Generation Spectroscopy ◽  
Bioinspired Materials ◽  
Polymer Stabilized ◽  
Insight Into

Polymer-stabilized liquid-liquid interfaces are an important and growing class of bioinspired materials that combine the structural and functional capabilities of advanced synthetic materials with naturally evolved biophysical systems. These platforms have the potential to serve as selective membranes for chemical separations, molecular sequencers, and to even mimic neuromorphic computing elements. Despite the diversity in function, basic insight into the assembly of well-defined amphiphilic polymers to form functional structures remains elusive, which hinders the continued development of these technologies. In this work we provide new mechanistic insight into the assembly of an amphiphilic polymer-stabilized oil/aqueous interface, in which the headgroups consist of positively charged methylimidazolium ionic liquids, and the tails are short, monodisperse oligodimethylsiloxanes covalently attached to the headgroups. We demonstrate using vibrational sum frequency generation spectroscopy and pendant drop tensiometery that the composition of the bulk aqueous phase, particularly the ionic strength, dictates the kinetics and structures of the amphiphiles in the organic phase as they decorate the interface. These results show that H-bonding and electrostatic interactions taking place in the aqueous phase bias the grafted oligomer conformations that are adopted in the neighboring oil phase. The kinetics of self-assembly were ionic strength dependent and found to be surprisingly slow, being composed of distinct regimes where molecules adsorb and reorient on relatively fast time scales, but where conformational sampling and frustrated packing takes place over longer timescales. These results set the stage for understanding related chemical phenomena of bioinspired materials in diverse technological and fundamental scientific fields and provide a solid physical foundation on which to design new functional interfaces.

Role of electrostatic interactions in the toxicity of titanium dioxide nanoparticles toward Escherichia coli

2012 ◽  
Vol 92 ◽  
pp. 315-321 ◽  
Author(s):  
Christophe Pagnout ◽  
Stéphane Jomini ◽  
Mandeep Dadhwal ◽  
Céline Caillet ◽  
Fabien Thomas ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Titanium Dioxide ◽  
Electrostatic Interactions ◽  
Titanium Dioxide Nanoparticles

Hybrid Inorganic/Organic Self-Assembled Clays Nanocomposites for Roll to Roll Fabrication in Photovoltaics

2009 ◽  
Vol 1196 ◽  
Author(s):  
Peter Njagwa Kariuki ◽  
Jessica Gendron ◽  
Christopher Matthew Madl ◽  
Jasper Chiguma ◽  
Michael E Hagerman ◽  
...  
Keyword(s):  
Titanium Dioxide ◽  
Indium Tin Oxide ◽  
Self Assembly ◽  
Titanium Dioxide Nanoparticles ◽  
Low Cost ◽  
Flexible Substrate ◽  
Roll To Roll ◽  
Organic Photovoltaic Materials ◽  
Self Assembled ◽  
Electrically Conducting Polymers

AbstractWe have been developing a new approach to layered hybrid (inorganic/organic) photovoltaic materials for fabrication by Roll-to-Roll (R2R) manufacturing. In this report, we combine the low cost and processability of organic electrically conducting polymers with the efficiency of dye sensitized titanium dioxide, semi-conductor quantum dots (CdSe) self-assembled on layered clay materials (Laponite) onto indium tin oxide coated flexible substrate polyethylene terephthalate (PET) substrates. We have shown electron transfer, guest-guest and host-guest interactions, charge separation, spectral line broadening, and quenching of fluorescence signals which indicate electronic coupling of the dye [Ru(bpy)3]2+ on a CdSe nanocrystal and titanium dioxide nanoparticles. Scanning electron microscopy and atomic force microscopy demonstrate successful nanoparticle formation and thin film self-assembly, as well as surface morphology and polymer thickness.

Removal of titanium dioxide nanoparticles by coagulation: effects of coagulants, typical ions, alkalinity and natural organic matters

2013 ◽  
Vol 68 (5) ◽  
pp. 1137-1143 ◽  
Author(s):  
H. T. Wang ◽  
Y. Y. Ye ◽  
J. Qi ◽  
F. T. Li ◽  
Y. L. Tang
Keyword(s):  
Titanium Dioxide ◽  
Ionic Strength ◽  
Natural Organic Matter ◽  
Titanium Dioxide Nanoparticles ◽  
Potential Hazard ◽  
Experimental Conditions ◽  
Polyaluminum Chloride ◽  
Tio2 Nps ◽  
Natural Organic Matters ◽  
Polyferric Sulfate

To investigate the possibility of removing titanium dioxide nanoparticles (TiO2 NPs) from water by coagulation, as well as to find the optimal coagulant and experimental conditions for TiO2 NP removal, four types of coagulant were adopted: polyferric sulfate (PFS), ferric chloride (FeCl3), polyaluminum chloride (PACl), and alum (Al2(SO4)3). It was found that the removal of TiO2 NPs by coagulation was affected by ionic strength, alkalinity, as well as types and dosages of coagulants. PFS and FeCl3 achieved much higher removal efficiency of TiO2 NPs than PACl and Al2(SO4)3 did. For 30 mg/L TiO2 NPs, a dosage of 0.3 mM PFS (as Fe) achieved 84% removal after coagulation followed by 30 min settlement. Optimal ionic strength (0.1 M NaCl or 0.03 M CaCl2) is of vital importance for the performance of PFS. Na2SO4 is unfavorable for the performance of PFS. Optimal alkalinity (0.01–0.03 M NaHCO3) is necessary for FeCl3 to remove TiO2 NPs. Natural organic matter, as represented by humic acid (HA) up to 11 mg/L, reduces the removal of TiO2 NPs by coagulation. These findings indicate that coagulation is a good option for the removal of TiO2 NPs from water, and more attention should be paid to the effects of water quality when using coagulation to remove TiO2 NPs from aqueous matrices. This provides a possible solution to alleviate the potential hazard caused by TiO2 NPs.

Development of Silver Nanoparticle Ink for Printed Electronics

2012 ◽  
Vol 2012 (1) ◽  
pp. 000935-000939
Author(s):  
Yiliang Wu ◽  
Ping Liu ◽  
Tony Wigglesworth
Keyword(s):  
Silver Nanoparticles ◽  
Silver Nanoparticle ◽  
Self Assembly ◽  
High Performance ◽  
Printed Electronics ◽  
Low Cost ◽  
High Conductivity ◽  
Large Area ◽  
Electrical Stability ◽  
Nanoparticle Ink

Printable conductors with high conductivity would be critical for low-cost printed electronics. In view of printability, conductivity, and electrical stability, metal such as gold or silver derived from solution-deposited precursor compositions would be an ideal candidate. Xerox has been exploring the use of silver nanoparticles as conductor precursor composition for printed electronics. This paper reviews our research in the development of alkylamine-stabilized silver nanoparticles that can be sintered at low temperature (∼ 120 °C) for high conductivity (&gt;10000 S/cm). Silver nanoparticle ink formulations based on these silver nanoparticles exhibit surface-energy independent printability which enables the fabrication of high-performance top-contact transistor devices, and self-assembly characteristic when printed on hydrophilic substrates which allows for large-area, defect-free source drain arrays to be printed with a narrow and uniform channel length.

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