Nanoparticles Research Papers - Academia.edu (original) (raw)

Tin oxide (SnO 2 ) is considered a very promising material as a high capacity Li-ion battery anode. Its adoption depends on a solid understanding of factors that affect electrochemical behavior and performance such as size and composition. We demonstrate here, that defined dispersions and structures can improve our understanding of Li-ion battery anode material architecture on alloying and co-intercalation processes of Lithium with Sn from SnO 2 on Si. Two different types of well-defined hierarchical Sn@SnO 2 core− shell nanoparticle (NP) dispersions were prepared by molecular beam epitaxy (MBE) on silicon, composed of either amorphous or polycrystalline SnO 2 shells. In 2 O 3 and Sn doped In 2 O 3 (ITO) NP dispersions are also demonstrated from MBE NP growth. Lithium alloying with the reduced form of the NPs and coinsertion into the silicon substrate showed reversible charge storage. Through correlation of electrochemical and structural characteristics of the anodes, we detail the link between the composition, areal and volumetric densities, and the effect of electrochemical alloying of Lithium with Sn@SnO 2 and related NPs on their structure and, importantly, their dispersion on the electrode. The dispersion also dictates the degree of co-insertion into the Si current collector, which can act as a buffer. The compositional and structural engineering of SnO 2 and related materials using highly defined MBE growth as model system allows a detailed examination of the influence of material dispersion or nanoarchitecture on the electrochemical performance of active electrodes and materials.

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- Chemical Engineering, Lithium, Silicon, Nanoparticles

Hypothesis: Dual-modality imaging agents, such as radiolabeled iron oxide nanoparticles (IO-NPs), are promising candidates for cancer diagnosis and therapy. We developed and evaluated aminosilane coated Fe 3 O 4 (10 ± 2 nm) as a tumor imaging agent in nuclear medicine through 3-aminopropyltriethoxysilane (APTES) functionalization. We evaluated this multimeric system of targeted 99m Tc-labeled nanoparticles (NPs) conjugated with a new RGD derivate (cRGDfK-Orn 3 -CGG), characterized as NPs-RGD as a potential thermal therapy delivery vehicle. Experiments: Transmission Electron Microscopy (TEM) and spectroscopy techniques were used to characterize the IO-NPs indicating their functionalization with peptides. Radiolabeled IO-NPs (targeted, non-targeted) were evaluated with regard to their radiochemical, radiobiological and imaging characteristics. In vivo studies were performed in normal and a m b 3 -positive tumor (U87MG glioblastoma) bearing mice. We also demonstrated that this system could reach ablative temperatures in vivo. Findings: Both radiolabeled IO-NPs were obtained in high radiochemical yield (>98%) and proved stable in vitro. The in vivo studies for both IO-NPs have shown significant liver and spleen uptake at all examined time points in normal and U87MG glioblastoma tumor-bearing mice, due to their colloidal nature. We have confirmed through in vivo biodistribution studies that the non-targeted 99m Tc-NPs poorly internalized in the tumor, while the targeted 99m Tc-NPs-RGD, present 9-fold higher tumor accumulation at 1 h p.i. Accumulation of both IO-NPs in other organs was negligible. Blocking experiments indicated target specificity for integrin receptors in U87MG glioblastoma cells. The preliminary in vivo study of applied alternating magnetic field showed that the induced hyperthermia is feasible due to the aid of IO-NPs.

- by Eirini Tsiapa and +1
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- Engineering, Nanoparticles, Mice, Glioblastoma

Talk on Graphene and Graphitic Carbon Nitride given at a Workshop at Manipal University, Jaipur on the 24th April 2018.

- by Claudius D'Silva
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- Materials Science, Synthesis of nanoparticles, Nanoelectronics, Nanocomposites

M odern civilization's inherited artworks have a powerful impact on society, from political, sociological, and anthropological points of view, so the conservation of our Cultural Heritage is fundamental for conveying to future generations our culture, traditions, and ways of thinking and behaving. In the conservation of cultural artifacts, scientists intervene in the degradation of often unique handcrafts, resulting from a delicate balance of aging, unpredicted events, environmental conditions, and sometimes incorrect previous restoration treatments, the details of which are often not precisely known.

- by rodorico giorgi
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- Cultural Heritage, Soft Matter, Self Assembly, Nanoparticles

The application of a new class of organogels as cleaning tools for painted surfaces is described. It combines some of the most attractive features of cleaning liquids and normal gels while diminishing the deleterious characteristics of both. Thus, the 'latent' gellant, polyethyleneimine (PEI), reacts with CO 2 at room temperature in solutions of several organic liquids to produce an ammonium carbamate form (PEICO 2 ). This charged species organizes itself into 3D polymer networks which immobilize the liquids as gels. The properties of the original solution (i.e. a free-flowing liquid) are re-established immediately after addition of a small amount of a weak acid which displaces the CO 2 molecules and makes the PEI chains positively charged. The visual changes are substantiated by rheological analyses. Results from analytical tests to determine the utility of these gels as cleaning tools for painted surfaces of historical and artistic interest, have been obtained from contact angle and FTIR measurements as well as visual comparisons of the surfaces before and after application of the gels. The analyses indicate that the PEICO 2 -based organogels were very effective in removing different surface patinas from painted supports. A surface layer of dammar was completely removed from a test canvas with oil paint, an aged painting from the XIX century, and a XV century oil-on-wood panel attributed to Mariotto di Cristoforo. Finally, a surface acrylic polymeric resin (used in a restoration performed during the 1960s) was also successfully removed from Renaissance wall paintings decorating the Santa Maria della Scala Sacristy in Siena, Italy. The isothermally rheoreversible gel approach described in this work represents a new, highly versatile, and very efficient method for removing aged surface patinas from works of art.

- by PIERO BAGLIONI
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- Archaeology, Cultural Heritage, Soft Matter, Rheology

A transparent solar cell window module based on the integration of traditional silicon solar cells and organic-inorganic nanocomposite material was designed and fabricated. The transparent solar cell window module was composed of a nanocomposite light-guide plate and traditional silicon solar cells. The preparation of the nanocomposite light-guide plate is easy without modification of the traditional casting process, the nanoparticles sol can be added directly to the polymethyl methacrylate (PMMA) monomer syrup during the process. The solar energy collected by this window can be used to power up small household electrical appliances.

- by Gan-Lin hwang
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- Engineering, Solar Cell, Nanoparticle, Nanoparticles

T he works of art and artifacts that constitute our cultural heritage are subject to deterioration, both from internal and from external factors. Surfaces that interact with the environment are the most prone to aging and decay; accordingly, soiling is a prime factor in the degradation of surfaces and the attendant disfigurement of a piece. Coatings that were originally intended to protect or contribute aesthetically to an artwork should be removed if they begin to have a destructive impact on its appearance or surface chemistry.

- by Lora Angelova and +2
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- Materials Science, Soft Matter, Art and Science, Self Assembly

Novel microfluidic tools allow new ways to manufacture and test drug delivery systems. Organ-on-a-chip systems - microscale recapitulations of complex organ functions - promise to improve the drug development pipeline. This review highlights the importance of integrating microfluidic networks with 3D tissue engineered models to create organ-on-a-chip platforms, able to meet the demand of creating robust preclinical screening models. Specific examples are cited to demonstrate the use of these systems for studying the performance of drug delivery vectors and thereby reduce the discrepancies between their performance at preclinical and clinical trials. We also highlight the future directions that need to be pursued by the research community for these proof-of-concept studies to achieve the goal of accelerating clinical translation of drug delivery nanoparticles.

- by Solange Massa
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- Biomedical Engineering, Microfluidics, Drug Discovery, Nanoparticles

- by Mehmet Dokmeci
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- Biomedical Engineering, Microfluidics, Drug Discovery, Nanoparticles

Surface-modifi ed quantum dots (QDs) are extensively used as fl uorescent labels for sensing and biosensing events. [ 1 , 2 ] Fluorescence resonance energy transfer (FRET) or electron-transfer quenching of the QDs are two fundamental photophysical mechanisms to probe sensing processes at the surface of the QDs. [ 2 , 3 ] Indeed, these photophysical mechanisms were implemented to detect ions, [ 4 ] to follow pH changes, [ 5 ] and to detect molecular substrates, such as saccharides or neurotransmitters. [ 6 ] Similarly, QDs have been widely used for biosensing, and different luminescence sensors that follow the formation of antigen-antibody complexes, [ 7 ] DNA hybridization [ 8 , 9 ] and aptamer-substrate complexes [ 10 ] were reported. Also, QDs have been extensively used to follow biocatalytic transformations and to quantitatively probe the substrates of enzymes. [ 9 , 11 ] Here we wish to report on the use of chemically modifi ed CdSe/ZnS QDs as fl uorescent probes for the analysis of explosives, and specifi cally, the detection of trinitrotoluene (TNT) or trinitrotriazine (RDX). The QDs are functionalized with electron donating ligands that bind nitro-containing explosives, exhibiting electron acceptor properties, to the QDs surfaces, via supramolecular donor-acceptor interactions. The concentration of the explosive substrates at the QDs via the donor-acceptor complexes leads to the quenching of the luminescence of the QDs, thus allowing the quantitative analysis of the substrates. The sensitivities of the QDs sensors are controlled by the electron donating properties of the capping layer that modifi es the particles. The rapid and sensitive analysis of nitroaromatic explosives attracts substantial recent efforts, and different optical [ 12 ] or electrochemical [ 13 ] TNT or RDX sensors were reported. Other sensors for explosives include surface acoustic wave (SAW) systems, where piezoelectric crystal coated with absorbing materials such as carbowax [ 14 ] or cyclodextrin polymers, [ 15 ] were

- by Ron Gill
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- Engineering, Materials Science, Nanobiotechnology, Nanoparticles

The present work shows that salt anions affect the activity of Pseudomonas cepacia lipase both in aqueous and in nonaqueous media (NAM) according to a Hofmeister series. The biocatalytic assay in water was the hydrolysis of p-nitrophenyl acetate, whereas the esterification between 1-hexyl--D-galactopyranoside and palmitic acid was followed in an organic solvent. The solid lipase preparations to be used in NAM were obtained through lyophilization in the presence of concentrated solutions of Hofmeister salts (Na 2 SO 4 , NaH 2 PO 4 / Na 2 HPO 4 , NaCl, NaBr, NaI, NaSCN). Salts affect enzyme activity in organic media through two mechanisms:

- by Maura Monduzzi
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- Engineering, Water, Soft Matter, Self Assembly

The present study is focused on developing a nanoparticle carrier for the photosensitizer protoporphyrin IX for use in photodynamic therapy. The entrapment of protoporphyrin IX (Pp IX) in silica spheres was achieved by modification of Pp IX molecules with an organosilane reagent. The immobilized drug preserved its optical properties and the capacity to generate singlet oxygen, which was detected by a direct method from its characteristic phosphorescence decay curve at near-infrared and by a chemical method using 1,3-diphenylisobenzofuran to trap singlet oxygen. The lifetime of singlet oxygen when a suspension of Pp IX-loaded particles in acetonitrile was excited at 532 nm was determined as 52 µs, which is in good agreement with the value determined for methylene blue in acetonitrile solution under the same conditions. The Pp IX-loaded silica particles have an efficiency of singlet oxygen generation (η ∆) higher than the quantum yield of free porphyrins. This high efficiency of singlet oxygen generation was attributed to changes on the monomer-dimer equilibrium after photosentisizer immobilization.

- by Adjaci Uchoa Fernandes
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- Chemistry, Photochemistry, Nanoparticle, Nanoparticles

Iron nanoparticles encapsulated by carbon are protected from reactions with their environment avoiding oxidation in ambient conditions and thus, preserving their magnetic properties. Such particles are good candidates for magnetic fluid hyperthermia. When graphite shells are present, acidic treatments allow the formation of carboxylic groups on the nanoparticle surface. Those carboxylic groups can be used for further complexation with the drug cisplatin. We show the possibility of loading cisplatin on such nanoparticles and that the loading is dependent on the degree of surface functionalization. The drug release is dependent on time and temperature, making it ideal for applications involving hyperthermia. We show the possibility of applying hyperthermia in vitro using these nanoparticles. When loaded with cisplatin a stronger cytotoxic effect is observed. Such particles could be potentially used as multimodal anti-cancer agents for therapies based on the synergistic effect of chemotherapy and hyperthermia.

- by Kai Krämer
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- Engineering, Carbon, Nanoparticles, Functionalization

The optimisation of cure conditions for epoxy system diglicidil ether of bisphenol A (DGEBA n = 0)/meta-xylylenediamine (m-XDA) has been made using experimental design. A quantitative analysis by Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) as well as making of nanocomposites of epoxy system with gold nanoparticles has been carried out. The knowledge of the optimum values for the variables of experimental design obtained with DSC in the system BADGE/m-XDA allows to study the adequate conditions of the nanocomposites curing process. DSC was used to measure the glass transition temperature (T g) and the degree of conversion (α). The FTIR method should be a more precise indicator of degree of conversion than DSC and it was used to corroborate the degree of conversion.

- by Francisco Fraga López and +1
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- Nanoparticles, Nanotechnology

Nanocomposite Titanium Dioxide (TiO2) doped Copper (Cu), Cu-TiO2 is synthesized by the impregnation method. This study aims to determine the effect of adding Cu to the TiO2 structure. The 1, 3, and 5 Cu with% TiO2 dissolved in 50 ml of deionized water, and 3 grams of TiO2 added. The compound is then stirred for 2 hours at 90 o C and dried in an oven at 110 o C for 30 minutes. Drying samples were calcined at 500 o C for 3 hours. Cu-TiO2 nanocomposites were characterized by XRD, SEM-EDX Mapping, and FTIR. The XRD analysis results show that Cu-TiO2 nanocomposite has a high level of crystallinity and has an anatase phase structure. The size of TiO2 crystals decreased with Cu doping and increased from 49.66 nm to 49.68 nm, with an increase in the composition of the doping mass of Cu. The SEM-EDX Mapping results show that all samples tend to clot, and Cu dopants evenly distributed on the surface of TiO2. FTIR analysis explained the presence of hydroxyl ions in the sample marked with the appearance of the absorption peak at 1658.78 cm-1 associated with OH bending of Ti-OH.

- by La Ode Asmin
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- Materials Science, Nanocomposites, Nanomaterials, Nanoparticles

Insight into extracellular electron transfer of microorganisms is important for our understanding of electron-transport pathways in bioelectrochemical systems (e.g. biological fuel cells and microbial electrolysis cells), as well as for biogeochemical cycles, biocorrosion, and bioremediation. Two principal mechanisms for extracellular electron transfer have been proposed: 1) electroactive metabolites/secretions serve as mediators in an indirect electron-transfer process; 2) electrons transfer directly from the cells to the electrodes via either membrane cytochromes or electrically conductive pili. The latter process has been defined as direct electron transfer (DET) and has been studied intensely. It is well known that several microbes are capable of transforming a range of metal ions/minerals into nanoparticles, which remain bound to the cell membrane. However, little is understood about the role of such metallic nanoparticles in physiological electrontransfer processes, and important questions remain regarding the details of the mechanisms involved.

- by Alfred Thumser
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- Bioelectrochemistry, Catalysis, Microbial Fuel Cells, Nanoparticles

We prepared SiO 2 @Ag core-shell nanospheres: silver nanoparticles ($4 ± 2 nm in diameter) coated silica nanospheres ($50 ± 10 nm in diameter). The preparation route is a modification of the Stöber method, and involves the preparation of homogeneous silica spheres at room temperature, combined with the deposition of silver nanoparticles from Ag + in solution, by using water/ethanol mixtures, tetraethylorthosilicate as Si source and silver nitrate as Ag source in a single-pot wet chemical route without an added coupling agent or surface modification, which leads to the formation of core@shell homogeneous nanospheres. We present the preparation and characterization of the SiO 2 @Ag core-shell nanospheres and also of bare silica spheres in the absence of silver, and propose a reaction mechanism for the formation of the core-shell structure.

The prominent nitric oxide (NO) donor [Ru(terpy)(bdqi)NO](PF 6 ) 3 has been synthesized and evaluated with respect to noteworthy biological effects due to its NO photorelease, including vascular relaxation and melanoma cell culture toxicity. The potential for delivering NO in therapeutic quantities is tenable since the nitrosyl ruthenium complex (NRC) must first reach the "target tissue" and then release the NO upon stimulus. In this context, NRC-loaded lipid carriers were developed and characterized to further explore its topical administration for applications such as skin cancer treatment. NRC-loaded solid lipid nanoparticles (SLN) and nanostructured lipid carriers were prepared via the microemulsification method, with average diameters of 275 ± 15 nm and 211 ± 31 nm and zeta potentials of −40.7 ± 10.4 mV and −50.0 ± 7.5 mV, respectively. In vitro kinetic studies of NRC release from nanoparticles showed sustained release of NRC from the lipid carriers and illustrated the influence of the release medium and the lyophilization process. Stability studies showed that NO is released from NRC as a function of temperature and time and due to skin contact. The encapsulation of NRC in SLN followed by its lyophilization, significantly improved the complex stability. Furthermore, of particular interest was the fact that in the NO photorelease study, the NO release from the NRC-loaded SLN was approximately twice that of just NRC in solution. NRC-loaded SLN performs well enough at releasing and protecting NO degradation in vitro that it is a promising carrier for topical delivery of NO.

- by Renata Fonseca Vianna Lopez and +1
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- Analytical Chemistry, Kinetics, Photochemistry, Scanning Electron Microscopy

Cytocompatible, co-doped cerium oxide nanoparticles exhibited strong upconversion properties that were found to kill lung cancer cells by inducing apoptosis thereby demonstrating the potential to be used as clinical contrast agents for... more

- by suresh babu
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- Nanoparticles, Chemical, Apoptosis, Endothelial Cells

For centuries, inflammatory/foreign body reactions have plagued the attempts of clinicians to use metals for tissue and bone reconstructions. Since corrosion contributes to the rejection of metal by the body, an extremely bioinert metal - tantalum - has been successfully used in medicine. The outstanding biocompatibility and flexibility of tantalum established the basis for a growing cadre of clinical applications. One important application which benefited from the introduction of powder (particle) metallurgy is use of tantalum as bone implants. Porous materials have re-shaped the landscape of bone implants, as they allow for bone ingrowth and biological fixation, and eliminate implant loosening and related treatment failures. The unique bone-mimicking properties of porous tantalum enabled the use of tantalum as a material for bulk implants, and not only for coatings, as is the case with other porous metals. Moreover, porous tantalum also facilitates the ingrowth of soft tissue, inc...

- by Nikita Oskolkov
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- Psychology, Cognitive Science, Regeneration, Nanoparticles

This paper reports an experimental investigation into force convective heat transfer of nanofluids flowing through a cylindrical minichannel under laminar flow and constant wall heat flux conditions. Sample nanofluids were prepared by dispersing different volumetric concentrations (0.2-0.8%) of nanoparticles in deionized water. The results showed that both the convective heat transfer coefficient and the Nusselt number of the nanofluid increase considerably with the nanoparticle volume fraction as well as the Reynolds number. Along with the enhanced thermal conductivity of nanofluids, the migration, interactions, and Brownian motion of nanoparticles and the resulting disturbance of the boundary layer are responsible for the observed enhancement of heat transfer coefficients of nanofluids.

- by SMS Murshed
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- Nanoparticles, Nanotechnology, Nanofluids, Nanoscience

Animal models, particularly rodents, are major translational models for evaluating novel anticancer therapeutics. In this review, different types of nanostructure-based photosensitizers that have advanced into the in vivo evaluation stage for the photodynamic therapy (PDT) of cancer are described. This article focuses on the in vivo efficacies of the nanostructures as delivery agents and as energy transducers for photosensitizers in animal models. These materials are useful in overcoming solubility issues, lack of tumor specificity, and access to tumors deep in healthy tissue. At the end of this article, the opportunities made possible by these multiplexed nanostructure-based systems are summarized, as well as the considerable challenges associated with obtaining regulatory approval for such materials. The following questions are also addressed: (1) Is there a pressing demand for more nanoparticle materials? (2) What is the prognosis for regulatory approval of nanoparticles to be used in the clinic?

- by Lip Yong Chung
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- Nanomaterials, Nanoparticles, Photodynamic Therapy, Cancer Therapy

Nanotechnology is an innovative discipline of science that has revolutionized the way we perceive the dimension and size of a molecule. The micrometric molecules accessed under the nanometric level generate nano-derived particles through which other nanodevices and nano-systems are contrived. Those nanoderived appliances are accommodable in effectuating copious different functions like physiological and biochemical processes in livestock species. The wide application of nanotechnology in animal science seems to be fateful unless and until nano-derived implements are recognized for execution in the field of animal breeding, production, health and management, and so on. The fundamental motivation behinds this article is to provide an insight into the application of nanostructures in the field of animal science to enhance the current frameworks. This review points out the current applications with appropriate measures of divergent nanotechnological particles, devices, and systems in the periphery of animal science.

- by Shubh Pravat Singh Yadav and +2
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- Animal Science, Synthesis of nanoparticles, Nanodevices, Nanoparticles

Nanoparticle-doped optical fibers are causing significant scientific interest in different application fields. Nanoparticle-doping of silica glass layers during optical fiber preform fabrication was so far reported by sol-gel and solution doping processes, by flame hydrolysis spraying and by pulling hollow cylinders from nanoparticle suspensions. A new method for fabrication of high quality nanoparticle-doped fibers is suggested. Proposed method is based on "flash vaporization" deposition process, previously reported as method to fabricate rare earth- and metal ion-doped specialty optical fibers. Experiments were made where SiO2 layers were deposited using "flash vaporization"-equipped MCVD system, adding vapors carrying metal or oxide nanoparticles into deposition zone. Analysis of produced preforms confirms presence of nanoparticles in deposited layers, albeit with low deposition rate due to weak thermophoretic forces acting on very small particles or agglomerations. Based on results, a number of improvements were suggested and implemented in fabrication process, device design and choice of precursor materials. "Flash vaporization" method was demonstrated as suitable method for deposition of nanoparticles in silica layers, permitting in-situ fabrication of complete preforms, providing easy upgrade path for existing MCVD and OVD deposition systems and allowing simultaneous co-doping by a wide range of other co-dopants.

- by Borut Lenardic
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- Nanoparticles, Doping, Particles, Fabrication

Magnetorheological fluids (MRFs) are typically thought of as Bingham-plastic (BP) fluids characterized by a yield stress. Partial substitution of micrometer-scale Fe particles with nanometer-scale Fe particles leads to bidisperse MRFs. This partial substitution mitigates particle sedimentation, but can reduce yield stress for high nanoparticle concentrations. We examine tradeoffs between increasing suspension stability versus decreasing in yield stress as nanoparticles are substituted for microparticles. Four groups of fluids with total Fe concentration of 50, 60, 70, and 80 wt% were considered. A sedimentation measuring device quantified sedimentation velocity of MRFs in a gravitational field. This sensor relates the rate of change of inductance relative to settling rate as Fe wt% decreases because of sedimentation. MRF flow curves were measured using a parallel disk rheometer and yield stress was identified using the BP flow model.

- by Norman Wereley
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- Engineering, Materials Science, Magnetic Materials, Stress

Effect of platinum nanoparticle size on catalytic reduction of nitrate in liquid phase was examined under ambient conditions by using hydrogen as a reducing agent. For the size effect study, Pt nanoparticles with sizes of 2, 4 and 8 nm were loaded silica support. TEM images of Pt nanoparticles showed that homogeneous morphologies as well as narrow size distributions were achieved during the preparation. All three catalysts showed high activity and were able to reduce nitrate below the recommended limit of 50 mg/L in drinking water. The highest catalytic activity was seen with 8 nm platinum; however, the product selectivity for N2 was highest with 4 nm platinum. In addition, the possibility of PVP capping agent acting as a promoter in the reaction is highlighted.

- by Minna Tiainen
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- Catalysis, Wastewater Treatment, Nanomaterials, Nanoparticles

In the past several years, there has been a trend in the sunscreen/ cosmetics industry to replace micron-sized titanium dioxide (TiO 2) particles with nanoscale materials. The increased use of nanoscale TiO 2 has resulted in questions about these and other nanoproducts. This study examines the effects of using nanoscale TiO 2 on ultraviolet (UV) attenuation in simple to complex sunscreen formulations. UV light attenuation, product stability, and potential damage to the skin barrier were examined with both nanoscale and microscale TiO 2 particles. Results indicate that none of the formulations decreased the barrier function of the skin and the best UV attenuation occurs when the TiO 2 particles are stabilized with a coating and evenly distributed such as with non-agglomerated coated nanoscale materials. This indicates that nanoscale TiO 2 may have better efficacy while lacking toxicity. Ré sumé Au cours des dernières années, nous avons constaté une tendance dans l'industrie solaire/cosmétique pour le remplacement des particules micron-taille de dioxyde de titane (TiO 2) avec des matériaux de nano-échelle. L'utilisation accrue des particules de TiO 2 l'échelle du nanométre a engendré des questions sur tous les produits contenant des matériaux nano-échelle. Cette étude examine les effets de l'utilisation de particule de TiO 2 a l'échelle du nanomètre sur l'atténuation des rayons UV dans les formulations de crème solaire simple et complexe. Nous avons étudié l'atténuation de la luminosité ultraviolet (UV), la stabilité du produit et les effets sur la fonction barrière de la peau, avec les particules de TiO 2 nano-échelle et micro-échelle. Les résultats indiquent que les particules a l'échelle du nanométre, enduits et non-aggloméré, fournissent une excellente atténuation UV, sans diminuer la fonction barrière de la peau. Ceci suggére que les particules de TiO 2 a l'échelle du nanométre ont une meilleure efficacité, sans poser des inquiétudes en ce qui concerne leur securité.

- by Bill Doub
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- Nanoparticle, Scanning Electron Microscopy, Morphology, Titanium

Purpose To develop a tumor-targeted drug delivery system based on solid lipid nanoparticles (SLNs) conjugated with the enzymatically cleavable polyethylene glycol (PEG). Methods SLNs loaded with paclitaxel (PTX) were prepared using the film ultrasonication method, followed by conjugation with a PEGylated peptide (Pp) that can specifically interact with matrix metalloproteinases (MMPs) that is over-expressed by tumor cells. The physicochemical characteristics of the Pp-PTX-SLNs were studied and the in vitro drug release, cytotoxicity and cell uptake of the formulations were investigated. Furthermore, using an animal model, the pharmacokinetic properties, biodistribution and anti-tumor activity of this system were evaluated.

- by Jie Zheng
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- Nanoparticles, Lipids, Mice, Pharmaceutical

The biosorption of food dyes FD&C red no. 40 and acid blue 9 onto Spirulina platensis nanoparticles was studied at different conditions of pH and temperature. Four isotherm models were used to evaluate the biosorption equilibrium and the thermodynamic parameters were estimated. Infra red analysis (FT-IR) and energy dispersive X-ray spectroscopy (EDS) were used to verify the biosorption behavior. The maximum biosorption capacities of FD&C red no. 40 and acid blue 9 were found at pH 4 and 298 K, and the values were 468.7 mg g À1 and 1619.4 mg g À1 , respectively. The Sips model was more adequate to fit the equilibrium experimental data (R 2 > 0.99 and ARE < 5%). Thermodynamic study showed that the biosorption was exothermic, spontaneous and favorable. FT-IR and EDS analysis suggested that at pH 4 and 298 K, the biosorption of both dyes onto nanoparticles occurred by chemisorption.

- by Luiz Pinto and +1
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- Thermodynamics, Nanoparticles, Multidisciplinary, Adsorption

The effect of six different preservatives on the production process and stability of resveratrol nanosuspensions was investigated. Nanosuspensions of the anti-oxidant resveratrol were prepared by high pressure homogenization (1,500 bar, 20 homogenization cycles). The preservatives used were: caprylyl glycol (0.75%), Euxyl PE 9010 (1.0%), Hydrolite-5 (2.0), Phenonip (0.75%), Rokonsal PB-5 (0.5%) and MultiEx Naturotics (2.0%). Preservation is essential for oral and dermal nanosuspensions, but can impair the stability. The effect of the preservatives on stability as a function of cycle numbers was determined by size measurements (photon correlation spectroscopy (PCS), laser diffraction (LD) and light microscopy). Zeta potential measurements were performed for determination of the Stern potential (measurements in water) and as stability criterion (measurements in original dispersion medium), to elucidate the mechanism of destabilization. The preservatives could be placed into three grou...

- by Kwabena Ofori-kwakye
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- Water, Electrochemistry, Nanoparticles, Pharmaceutical Chemistry

Topotecan (TPT), a highly active anticancer camptothecin drug, would benefit from nanocarrier-mediated site-specific and intracellular delivery because of a labile lactone ring whose hydrolysis inactivates the drug, poor cellular uptake resulting from both lactone hydrolysis and a titratable phenol hydroxyl, and the schedule-dependency of its efficacy due to its mechanism of action. We have encapsulated topotecan in liposomes using transmembrane gradients of triethylammonium salts of polyphosphate (Pn) or sucroseoctasulfate (SOS). Circulation lifetimes were prolonged, and the rate of drug release in vivo depended on the drug load (T 1/2 = 5.4 h vs. 11.2 h for 124 and 260 g TPT/mol PL, respectively) and the nature of intraliposomal drug complexing agent used to stabilize the nanoliposome formulation (T 1/2 = 11.2 h vs. 27.3 h for Pn and SOS, respectively). Anti-EGFR and anti-HER2-immunoliposomal formulations dramatically increased uptake of topotecan compared to nontargeted nanoliposomal topotecan and poorly permeable free topotecan in receptor-overexpressing cancer cell lines, with a corresponding increase in cytotoxicity in multiple breast cancer cell lines and improved antitumor activity against HER2-overexpressing human breast cancer (BT474) xenografts. We conclude that stabilization of topotecan in nanoliposomes significantly improves the targetability and pharmacokinetic profile of topotecan, allowing for highly active formulations against solid tumors and immunotargeting to cancer-overexpressing cell surface receptors.

- by Daryl Drummond
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- Biomedical Engineering, Breast Cancer, Nanoparticle, Nanoparticles

Background: 1E10 monoclonal antibody is a murine anti-idiotypic antibody that mimics N-glycolyl-GM3 gangliosides. This antibody has been tested as an anti-idiotypic cancer vaccine, adjuvated in Al(OH) 3 , in several clinical trials for melanoma, breast, and lung cancer. During early clinical development this mAb was obtained in vivo from mice ascites fluid. Currently, the production process of 1E10 is being transferred from the in vivo to a bioreactor-based method.

- by Adolfo Castillo
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- Engineering, Thermodynamics, Organic Chemistry, Physical Chemistry

We report a procedure to prepare highly 14 monodisperse copper telluride nanocubes, nanoplates, and 15 nanorods. The procedure is based on the reaction of a 16 copper salt with trioctylphosphine telluride in the presence 17 of lithium bis(trimethylsilyl)amide and oleylamine. CuTe 18 nanocrystals display a strong near-infrared optical 19 absorption associated with localized surface plasmon 20 resonances. We exploit this plasmon resonance for the 21 design of surface-enhanced Raman scattering sensors for 22 unconventional optical probes. Furthermore, we also 23 report here our preliminary analysis of the use of CuTe 24 nanocrystals as cytotoxic and photothermal agents. 25 C opper-based chalcogenides are used in a wide range of 26

- by Reza Zamani
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- Nanoparticles, Copper, Mice, Surface plasmon resonance

The complexes of N-disubstituted, N'-ethoxy carbonyl thioureas with copper, nickel and cobalt have been synthesized and studied. NMR spectra and magnetic data have shown square-planar NiL2 and facor mer-CoL 3 compounds. The existence of copper(III)/copper(II) and copper(II)/copper(I) redox systems has been chemically and electrochemically proved in solution.

- by Isabel Reims
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- Materials Engineering, Condensed Matter Physics, Inorganic Chemistry, Nanoparticles

Bacteriorhodopsin (bR) is a membrane protein found in the archae Halobacterium salinarum. Here, we studied wild type bR and especially the triple mutant bR, 3Glu [E9Q/E194Q/E204Q], in combination with wide gap semiconductor TiO 2 for their suitability as efficient light harvester in solar cell. Our differential scanning calorimetry data show thermal robustness of bR wild type and 3Glu mutant, which make them good candidates as photosensitizer in solar cells. Molecular modeling indicates that binding of bR to the exposed oxygen atoms of anatase TiO 2 is favorable for electron transfer and directed by local, small distance interactions. A solar cell, based on bR wild type and bR triple mutant immobilized on nanocrystalline TiO 2 film was successfully constructed. The photocurrent density-photo voltage (J-V ) characteristics of bio-sensitized solar cell (BSSC), based on the wild type bR and 3Glu mutant adsorbed on nanocrystalline TiO 2 film electrode were measured. The results show that the 3Glu mutant displays better photoelectric performance compared to the wild type bR, giving a short-circuit photocurrent density (J SC ) of 0.09 mA/cm 2 and the open-circuit photovoltage (V OC ) 0.35 V, under an illumination intensity of 40 mW/cm 2 .

- by Sławomir Filipek
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- Engineering, Technology, Photosynthesis, Titanium

The physico-chemical properties and in vivo efficacies of two nanoparticulate systems delivering the antiparkinsonian drug bromocriptine (BC) were compared in the present study. Monoolein Aqueous Dispersions (MADs) and Nanostructured Lipid Carriers (NLCs) were produced and characterized. Cryogenic transmission electron microscopy (cryo-TEM) and X-ray diffraction revealed the morphology of MAD and NLC. Dimensional distribution was determined by Photon Correlation Spectroscopy (PCS) and Sedimentation Field Flow Fractionation (SdFFF). In particular, BC was shown to be encapsulated with high entrapment efficiency both in MAD and in NLC, according to SdFFF combined with HPLC. Two behavioral tests specific for akinesia (bar test) or akinesia/bradykinesia (drag test) were used to compare the effects of the different BC formulations on motor disabilities in 6-hydroxydopamine hemilesioned rats in vivo, a model of Parkinson's disease. Both free BC and BC-NLC reduced the immobility time in the bar test and enhanced the number of steps in the drag test, although the effects of encapsulated BC were longer lasting (5 h). Conversely, BC-MAD was ineffective in the bar test and improved stepping activity in the drag test to a much lower degree than those achieved with the other preparations. We conclude that MAD and NLC can encapsulate BC, although only NLC provide long-lasting therapeutic effects possibly extending BC half-life in vivo.

- by Daniel Mandler
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- Chemistry, Scanning Electron Microscopy, Nanoparticles, Polymers

Adhesive silks spun by aquatic caddisfly (order Trichoptera) larvae are used to build both intricate protective shelters and food harvesting nets underwater. In this study, we use 13 C and 31 P solid-state NMR and wide angle X-ray diffraction (WAXD) as tools to elucidate molecular protein structure of caddisfly larval silk from the species Hesperophylax consimilis. Caddisfly larval silk is a fibroin protein based biopolymer containing mostly repetitive amino acid motifs. NMR and X-ray results provide strong supporting evidence for a structural model in which phosphorylated serine repeats (pSX) 4 complex with divalent cations Ca 2+ and Mg 2+ to form rigid nanocrystalline β-sheet structures in caddisfly silk. 13 C NMR data suggests that both phosphorylated serine and neighboring valine residues exist in a β-sheet conformation while glycine and leucine residues common in GGX repeats likely reside in random coil conformations. Additionally, 31 P chemical shift anisotropy (CSA) analysis indicates that the phosphates on phosphoserine residues are doubly ionized, and are charge-stabilized by divalent cations. Positively charged arginine side chains also likely play a role in charge stabilization. Finally, WAXD results finds that the silk is at least 7−8% crystalline, with β-sheet interplane spacings of 3.7 and 4.5 Å.

- by Gregory Holland
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- Engineering, Nanoparticles, Magnetic Resonance Spectroscopy, Biological Sciences

This study investigated the removal efficiency and mechanisms of water contaminants (mainly N-nitrosamines) during municipal wastewater reclamation by a membrane bioreactor (MBR) and nanofiltration (NF) hybrid system. The removal of bulk water contaminants was governed by the microbial activities in the MBR and molecular weight cut-off (MWCO) of the NF membranes. The removal of N-nitrosamines by the MBR was primarily attributed to biodegradation by aerobic bacteria, which can be determined by the reactivity of the amine functional groups with the catabolic enzymes (removal efficiency=45-84%). Adsorption and formation of membrane fouling can enhance the removal of N-nitrosamines by the NF membranes. However, size-exclusion is found to play a major role in the removal of N-nitrosamines by the NF membranes since the removal efficiencies of N-nitrosamines varied significantly depending on molecular weight of the N-nitrosamines and MWCO of the NF membranes (removal efficiency: NE90>NE...

- by Kangmin Chon
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- Water Purification, Nanoparticles, Multidisciplinary, Ultrafiltration

In this work, Mg 2+ doped hydroxyapatite (Mg-HAP) nanoparticles were produced by a reactionprecipitation process by using a spinning disc reactor (SDR) at high rotational speed. The production process of these nanoparticles consisted of the neutralization reaction between two aqueous solutions of calcium chloride and ammonia orthophosphate at room temperature. By operating at pH = 10, a high purity Mg-HAP nanoparticles were obtained. In particular, they were 51 nm in average size when the two reagents were fed over the disc symmetrically at 3 cm from the disc center and a rotational speed of the disc reactor equal to 1400 r/min was adopted.

- by Augusto Francesco D'Intino and +1
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- Synthesis of nanoparticles, Hydroxyapatite, Nanomaterials, Nanoparticles

Graphene has attracted great interest for its superior physical, chemical, mechanical, and electrical properties that enable a wide range of applications from electronics to nanoelectromechanical systems. Functionalization is among the significant vectors that drive graphene towards technological applications. While the physical properties of graphene have been at the center of attention, we still lack the knowledge framework for targeted graphene functionalization. In this critical review, we describe some of the important ...

- by Bingqian Xu
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- Physics, Electronics, Silicon, Nanoparticles

Mg-Gd-Mn nanoferrites with formulae Mg 0.9 Mn 0.1 Gd y Fe 2 À y O 4 , where y¼ 0.05, 0.1, 0.2 and 0.3, have been synthesized by solution combustion technique. The dc resistivity was observed to decrease with the increase in temperature. Dielectric constant (ε′) and loss tangent (tan δ) have been found to be increasing with an increase in temperature while with an increase in frequency both have been found to be decreasing. The ac electrical conductivity (s ac) has been studied as a function of temperature at different frequencies and has been observed to be increasing with the increase in temperature. The Mössbauer spectroscopy has been carried out so as to authenticate our previously reported results on the superexchange interactions.

Palladium-based nanoparticles immobilized in polymeric matrices were applied to the reductive dechlorination of 3,3′,4,4′-tetrachlorobiphenyl (PCB77) at room temperature. Two different dechlorination platforms were evaluated using (1) Pd nanoparticles within conductive polypyrrole films; or (2) immobilized Fe/Pd nanoparticles within polyvinylidene fluoride microfiltration membranes. For the first approach, the polypyrrole film was electrochemically formed in the presence of perchlorate ions that were incorporated into the film to counterbalance the positive charges of the polypyrrole chain. The film was then incubated in a solution containing tetrachloropalladate ions, which were exchanged with the perchlorate ions within the film. During this exchange, reduction of tetrachloropalladate by polypyrrole occurred, which led to the formation of palladium nanoparticles within the film. For the second approach, the membranesupported Fe/Pd nanoparticles were prepared in three steps: polymerization of acrylic acid in polyvinylidene fluoride microfiltration membrane pores was followed by ion exchange of Fe 2+ , and then chemical reduction of the ferrous ions bound to the carboxylate groups. The membranesupported iron nanoparticles were then soaked in a solution of tetrachloropalladate resulting in the deposition of Pd on the Fe surface. The nanoparticles prepared by both approaches were employed in the dechlorination of PCB77. The presence of hydrogen was required when the monometallic Pd nanoparticles were employed. The results indicate the removal of chlorine atoms from PCB77, which led to the formation of lower chlorinated intermediates and ultimately biphenyl. Toxicity associated with vascular dysfunction by PCB77 and biphenyl was compared using cultured endothelial cells. The data strongly suggest that the dechlorination system used in this study markedly reduced the proinflammatory activity of PCB77, a persistent organic pollutant.

- by Dibakar Bhattacharyya
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- Engineering, Persistent Organic Pollutants, Electrochemistry, Nanoparticle

The use of modified nanoparticles in interactions with biological targets is attracting rapidly increasing attention. In this Full Paper, the application of gold nanoparticles capped with mercaptoethanesulfonate (Au-MES NPs) as effective inhibitors of Herpes simplex virus type 1 infection based on their ability to mimic cell-surface-receptor heparan sulfate is described. Mechanistic studies reveal that Au-MES NPs interfere with viral attachment, entry, and cell-to-cell spread, thereby preventing subsequent viral infection in a multimodal manner. The ligand multiplicity achieved with carrier nanoparticles is crucial in generating polyvalent interactions with the virus at high specificity, strength, and efficiency. Such multivalent-nanoparticlemediated inhibition is a promising approach for alternative antiviral therapy.

- by Ronit Sarid
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- Cell Adhesion, Nanoparticles, Multidisciplinary, Biomimicry

The nanoparticles are superparamagnetic at room temperature and display a blocking temperature of 17.6 K. Their anisotropy (2.7 10 5 J m À3) is determined to be more than two orders of magnitude higher than that of the bulk NiFe alloy (10 3 J m À3) and is close to that determined for Fe nanoparticles of the same size. Still, they display a magnetization of (1.69 AE 0.05) m B per metallic atom, identical to that of the bulk NiFe alloy. Combining the results from X-ray absorption and Mçssbauer studies, we evidence a progressive enrichment in iron atoms from the core to the surface of the nanoparticles. These results are discussed in relation to both size and chemical effects. They show the main role played by the enriched Fe surface on the magnetic properties and address the feasibility of soft magnetic materials at the nanoscale.

- by Pierre Lecante
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- Crystallization, Nanoparticles, Nanotechnology, Multidisciplinary

The plasmon resonance of gold nanoparticles (GNPs) synthesized on a protein template senses formation of advanced glycosylated end products (AGEs). A graded alteration of plasmon resonance (both the peak and intensity are affected) is observed as the glycation progresses. Transmission electron microscopy shows significant shift of the size distribution of GNPs in presence of glycation. The higher plasmon resonance is thus caused by increased formation of GNPs, which in turn is attributed to a larger number of smaller particles. To study the binding of the protein with the GNP, infrared (IR) spectroscopy and circular dichroism (CD) studies were undertaken. Whereas the CD studies confirmed the emergence of β-structure and loss of α-helix, the IR data indicated glycationinduced alterations in the amide I region. The proposed sensor for formation of AGEs thus apparently operates by direct or indirect conjugation with amino groups. Incidentally, glycation and AGE formation are responsible for a number of diabetes-related clinical conditions, and the present approach could be adopted for use for a simple colorimetric assay for the AGEs.

- by Chanchal Mitra
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- Technology, Electron Microscopy, Nanoparticles, Transmission Electron Microscopy

The purpose of this study is to investigate the combined influence of process parameters (independent variables) such as homogenization speed (X 1 ), duration (X 2 ), and temperature (X 3 ) during the preparation of dacarbazine-loaded cubosomes. Box-Behnken design was used to rationalize the influence of these three factors on two responses, namely particle size (Y 1 ) and encapsulation efficiency (Y 2 ). Independent and dependent variables were analyzed with multiple regressions to establish a fullmodel second-order polynomial equation. F value was calculated to confirm the omission of insignificant parameters or interactions of parameters from the analysis to derive a reduced-model polynomial equation to predict the Y 1 and Y 2 of dacarbazine-loaded cubosomes. Pareto charts were also obtained to show the effects of X 1 , X 2 , and X 3 on Y 1 and Y 2 . For Y 1 , there was a model validated for more accurate prediction of response parameter by performing checkpoint analysis. The optimization process and Pareto charts were obtained automatically and they predicted the levels of independent parameters X 1 , X 2 , and X 3 (0.889794, 0.11886, and 0.56201, respectively) and minimized Y 1 . The optimal process parameters (homogenization's speed=~24,000 rpm, duration=5.5 min, and temperature=76°C) led to the production of cubosomes with 85.6 nm in size and 16.7% in encapsulation efficiency. The Box-Behnken design proved to be a useful tool in the preparation and optimization of dacarbazine-loaded cubosomes. For encapsulation efficiency (Y 2 ), further studies are needed to enhance the result and improve the model for such water-soluble drug encapsulation in cubosomes.

- by James Murowchick
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- Algorithms, Nanoparticles, Optimization, Process

The main purpose of this study is to present a systematically assessment of wear characteristics of hybrid dental composites. Lanthanum oxide (La2O3) nanofillers are an imperative part of fillers in hybrid dental composites to increase their cosmetic features and radiopacity that are added as a second filler along with quartz microfillers. In this research, hybrid nanocomposite samples are synthesized by different content of La2O3 nanofillers to study their effect on surface behaviour, friction coefficient and wear resistance that further discussed using scanning electron microscopy (SEM) images of the wear track and debris. The results provide a significant influence of nanofillers on wear resistance with samples having higher nanofillers showing lower wear resistance; however, coefficient of friction reaches an optimum and increase with higher content. The wear behaviour is also related to micro‐hardness of specimens to find a detailed understanding of wear mechanism.

- by Mehrdad Khakbiz
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- Nanoparticles, Dental Composites