Microscale garbage “collectors” cleans polluted water


By Michael Berger. Copyright © Nanowerk

3D rendered Molecule (Abstract) with Clipping Path(Nanowerk Spotlight) The construction of artificial micro- and nanomotors is a high priority in the nanotechnology field owing to their great potential for diverse potential applications, ranging from targeted drug delivery, on-chip diagnostics and biosensing, or pumping of fluids at the microscale to environmental remediation.

Particular attention has been given to self-propelled chemically-powered micro/nanoscale motors, such as catalytic nanowires (read more: “”Another nanotechnology step towards ‘Fantastic Voyage'”), microtube engines (read more: “Microbots transport, assemble and deliver micro- and nanoscale objects”) or spherical Janus microparticles (read more: “Novel motor system powered by polymerization”). In new work, researchers in Germany have now reported the first example of micromotors for the active degradation of organic pollutants in solution.

The novelty of this work lies in the synergy between internal and external functionality of the micromotors. “Previously, some groups tried to demonstrate the use of catalytic nanomotors for biomedical applications – including ours – on-chip biosensors and capture of bio species,” Dr. Samuel Sánchez, Group Leader Smart Nano-Bio-Systems, Max Planck Institute for Intelligent Systems, tells Nanowerk. “However, the toxicity of the fuel employed still limits their real applications. We imagined that environmental applications might be another field to explore, where the use of hydrogen peroxide is not controversial.” In that direction, Wang’s group reported the removal of oil droplets (“‘Microsubmarines’ designed to help clean up oil spills”) from solution, not degrading them.

Now, Sánchez and his collaborators went one step beyond that and demonstrated the total removal of contaminants using micromotors. Indeed, the chemical is used for the self-propulsion and for the remediation when interacts with the outer layer of the micromachine. “We have demonstrated the ability of self-propelled micromotors to oxidize organic pollutants in aqueous solutions through a Fenton process,” explains Sánchez.

“The combination of mixing and releasing iron ions in liquids results in a rate of removal of model pollutant (rhodamine 6G) ca. 12 times higher than when the Fenton oxidation process is carried out with nonpropelling metallic iron tubes.” Reporting their results in The November 1, 2013 online edition of ACS Nano (“Self-Propelled Micromotors for Cleaning Polluted Water”), the research team from Max Planck, the Leibniz Institute for Solid State and Materials Research Dresden, and the Chemnitz University of Technology demonstrates that micromotors boost the Fenton oxidation process (read more about Fenton reactions at the bottom of this article) without applying external energy, and complete degradation of organic pollutants is achieved.

 

          Schematic process for the degradation of polluted water into inorganic products by multifunctional micromotors

Schematic process for the degradation of polluted water (rhodamine 6G as model contaminant) into inorganic products by multifunctional micromotors. The self propulsion is achieved by the catalytic inner layer (Pt), which provides the motion of the micromotors in H2O2 solutions. The remediation of polluted water is achieved by the combination of Fe2+ ions with peroxide, generating OH• radicals, which degrade organic pollutants. (Reprinted with permission from American Chemical Society)

Sánchez notes that, if desired, the micromotors can be easily recovered using a magnet once the water purification process has been completed and the excess of hydrogen peroxide can be easily decomposed to pure water and oxygen under visible light. The team fabricated their tubular bubble-propelled micromotors containing small amounts of metallic iron (from 20 to 200 nm layer thickness) as outer layer and platinum as inner layer. The mechanism of degradation is based on Fenton reactions relying on spontaneous acidic corrosion of the iron metal surface of the micromotors in the presence of hydrogen peroxide, which acts both as a reagent for the Fenton reaction and as main fuel to propel the micromotors.

Moreover, the ability of self-propelled, tubular micromotors to improve mixing results in a synergetic effect that enhances water remediation without applying external energy. This work can pave the way for the use of multifunctional micromotors for environmental applications where the use of hydrogen peroxide is not a major drawback but a co-reagent. Sánchez adds that the high efficiency of the oxidation of organic pollutants achieved by the Fe/Pt catalytic micromotors reported in this work is of importance for the design of new and faster water treatments, such as the decontamination of organic compounds in wastewaters and industrial effluents. The aim of this study was to fabricate an autonomous microscopic cleaning system that is working without external energy input in a much faster and convenient way.

The micromotors offer this ability to move the catalyst around without external actuation or addition of catalyst (iron salts) to achieve water remediation, removal of organic dyes, etc. However, as the researchers point out, this is an application especially for microscale environments. “It is, unfortunately, clear that we would not use the micromotors in a large reactor vessel to clean huge amounts of water,” says Sánchez. Nevertheless, the high efficiency of the oxidation of organic pollutants achieved by the Fe/Pt catalytic micromotors reported here is of importance for the design of new and faster water treatments, such as the decontamination of organic compounds in wastewaters and industrial effluents.

“We have proven that the usefulness of the micromotors lies not solely in their capacity to move, but to exploit their motion using their external surface to enhance useful catalytic reactions,” says Sánchez. “This work could open a new research line towards coupling a variety of catalytic reactions in self-propelled devices where the presence of hydrogen peroxide is not a disadvantage. We expect that a rich variety of contaminants can be in the next years be cleaned.”

Watch the micromotor in action. A synergetic effect is achieved taking advantage of the release of the iron ions from the outer layer of the micromotors and their active motion in the solution.

About Fenton reactions The Fenton method is one of the most popular advanced oxidation processes for the degradation of organic pollutants, utilizing the hydroxyl radical (OH•) as its main oxidizing agent. The generation of OH• in the Fenton method occurs by reaction of H2O2 in the presence of Fe(II). However, one disadvantage of these processes is that Fe ions in solution must be removed after the treatment to meet regulations for drinking water. In order to diminish and, in the best scenario, solve the problems caused by the presence of Fe ions in treated effluents and decrease the costs of recovery, the use of heterogeneous Fenton catalysts is a promising strategy that could allow for the degradation of pollutants by Fenton processes without the requirement of dissolved iron salts. The micromotors fabricated in this work can be included as a new type of heterogeneous Fenton catalyst. With this method the remaining iron in the solution is one to three orders of magnitude lower than in conventional Fenton processes.

Read more: http://www.nanowerk.com/spotlight/spotid=33493.php#ixzz2mN10wW9l

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Automated and scalable inline two-stage synthesis process for high quality colloidal quantum dots


By Michael Berger. Copyright © Nanowerk

longpredicte(Nanowerk Spotlight) Colloidal quantum dot (CQDnanocrystals are attractive materials for optoelectronics, sensing devices and  third generation photovoltaics, due to their low cost, tunable bandgap – i.e.  their optical absorption can be controlled by changing the size of the CQD  nanocrystal – and solution processability. This makes them attractive candidate  materials for cheap and scalable roll-to-roll printable device fabrication  technologies.

 

One key impediment that currently prevents CQDs from fulfilling  their tremendous promise is that all reports of high efficiency devices were  from CQDs synthesized using manual batch synthesis methods (in classical  reaction flasks).

 

Researchers have known that chemically producing nanocrystals  of controlled and narrow size-distributions requires stringent control over the  reaction conditions – e.g. temperature and reactant concentration – which is  only practical for small-scale reactions.

 

Such a synthesis is extremely  difficult to scale up, hence very costly to mass produce without severely  compromising quality.   The reason for this is that, just like rain droplets,  nanocrystals form sequentially by ‘nucleation’ and ‘growth’. Both these  phenomena are highly sensitive to temperature and reagent concentration.  Moreover, nucleation and growth must occur at substantially different  temperatures and, in fact, to obtain nanocrystals of uniform sizes, one must be  able to rapidly cool down the reaction from the nucleation temperature to the  growth temperature.

 

Hence, the quality of the product is contingent upon how  well and fast one can homogenize the reactor, both chemically and thermally.   Unfortunately, the only way to scale up batch reactors is by  increasing their volume, whereupon it becomes difficult to homogenize the  reactor and impractical to rapidly cool. The end result is nanocrystals of  low-quality and broad size distributions, which are not useful for fabricating  devices.

Some researchers have sought to circumvent this limitation by  conducting the reactions in narrow fluidic channels (less than a 1 mm in  diameter) while the reactants are continuously pumped through the channels, so  called ‘continuous-flow reactors’.

 

Conceptually, this scheme has several advantages. Narrow-width  channels afford uniform heating and mixing of the reaction, while the reaction  is scalable by simply increasing channel length and pump rate of the reagents.  This sort of scaling does not effect the quality of the product, because the  channel width, and hence the effective reaction volume, remains the same.  Despite these advantages, most attempts to use continuous-flow reactors in the  past have resulted in nanocrystals with a much lower quality than the batch  produced ones.

 

“We have analyzed the nucleation and growth of CQDs in  continuous-flow reactors and realized that, in order to achieve controllable  size and narrow size-distributions, one must employ two temperature stages in  the reactor: one for nucleation, and another for growth,” Osman Bakr, an  assistant professor in the Solar & Photovoltaics Engineering Research Center at King  Abdullah University of Science and Technology (KAUST), tells Nanowerk.

“By  separating these two crucial steps in the formation of the CQDs in time,  temperature, and space, we were able to obtain very high quality nanocrystals,  as good as the best batch synthesis, by a process that is low-cost,  mass-producible, and automated.”

Schematic of a conventional batch synthesis setup and a dual-stage continuous flow reactor setup

 

 

Schematic of (a) a conventional batch synthesis setup and (b) a  dual-stage continuous flow reactor setup with precursor A (Pb-oleate,  octadecene) and precursor B (bis(trimethylsilyl) sulfide in octadecene).  (Reprinted with permission from American Chemical Society)

 

Reporting their findings in ACS Nano (“Automated Synthesis of Photovoltaic-Quality Colloidal Quantum  Dots Using Separate Nucleation and Growth Stages”), Bakr and his team  demonstrated the quality of the CQDs produced by their method by using them to  make CQD-based solar cells that showed very high efficiencies.

 

“In this paper, we developed an automated, scalable, in-line  synthesis methodology of high-quality CQDs based on a flow-reactor with two  temperature-stages of narrow channel coils,” says Professor Ted Sargent from the  University of Toronto who, together with Bakr, led this work. “The flow-reactor  methodology not only enables easy scalability and cheap production, but also  affords rapid screening of parameters, automation, and low reagent consumption  during optimization. 

Moreover, the CQDs are as good in quality and device  performance as the best CQDs that are produced in the traditional batch  methodology.”   The team also developed a general theory for how one can use the  flow-reactors to finely tune the quality and size distribution of the CQDs, and  explained why previous attempts of using flow-reactors based on a  single-temperature-stage, as opposed to a dual-temperature-stage, necessarily  produce CQDs of low-quality and broad size distribution.

 

This work paves the way towards the large-scale and affordable  synthesis of high-quality CQD nanocrystals in tunable sizes, enabling  photovoltaics, light-emitting diodes, photodetectors, and biological tagging  technologies that take advantage of the nanoscale properties of those promising  materials.

 

“Over the last ten years we have seen tremendous advancements in  software and computer integration, in items that we use in our everyday lives,”  says Bakr. “Flow-reactors as a platform are ideally placed to take advantage of  this trend. Software that automates the routines of flow-reactors already  exists. In the near future, researchers will be able to run and monitor hundreds  of experiments to produce CQDs from home using a mobile app.

 

Moreover, because  flow-reactors contain very few moving parts, essentially just programmable  pumps, I expect that it will become an automated research platform that most  labs studying nanocrystals can afford.”   “Our work has shown that flow-reactors can produce nanocrystals  that are as good as the best batch produced reactions, with exquisite control  over reaction conditions,” he adds. “We believe that this will encourage the  nanomaterials community to take advantage of the enormous productivity gains in  R&D afforded by flow-reactors, which other chemical industries, such as  pharmaceuticals, are currently utilizing earnestly.”

Read more: http://www.nanowerk.com/spotlight/spotid=32945.php#ixzz2j2YbZvu8

Nanoparticle Super Antioxidant Developed at Rice University


Scientists create a super antioxidant with  nanoparticles

QDOTS imagesCAKXSY1K 8(Nanowerk News) Scientists at Rice University are  enhancing the natural antioxidant properties of an element found in a car’s  catalytic converter to make it useful for medical applications.
Rice chemist Vicki Colvin led a team that created small, uniform  spheres of cerium oxide and gave them a thin coating of fatty oleic acid to make  them biocompatible. The researchers say their discovery has the potential to  help treat traumatic brain injury, cardiac arrest and Alzheimer’s patients and  can guard against radiation-induced side effects suffered by cancer patients.
Their nanoparticles also have potential to protect astronauts  from long-term exposure to radiation in space and perhaps even slow the effects  of aging, they reported.
The research appears this month in the American Chemical Society  journal ACS Nano (“Antioxidant Properties of Cerium Oxide Nanocrystals  as a Function of Nanocrystal Diameter and Surface Coating”).
Oleylamine (red dots) and oleac acid (blue) layers serve to protect a cerium oxide nanosphere
Oleylamine (red dots) and oleac acid (blue) layers serve to protect  a cerium oxide nanosphere that catalyzes reactive oxygen species by absorbing  them and turning them into less-harmful molecules. The finding could help treat  injuries, guard against radiation-induced side effects of cancer therapy and  protect astronauts from space radiation. (Credit: Colvin Group/Rice University)
Cerium oxide nanocrystals have the ability to absorb and release  oxygen ions — a chemical reaction known as reduction oxidation, or redox, for  short. It’s the same process that allows catalytic converters in cars to absorb  and eliminate pollutants.
The particles made at Rice are small enough to be injected into  the bloodstream when organs need protection from oxidation, particularly after  traumatic injuries, when damaging reactive oxygen species (ROS) increase  dramatically.
The cerium particles go to work immediately, absorbing ROS free  radicals, and they continue to work over time as the particles revert to their  initial state, a process that remains a mystery, she said. The oxygen species  released in the process “won’t be super reactive,” she said.
Colvin said cerium oxide, a form of the rare earth metal cerium,  remains relatively stable as it cycles between cerium oxide III and IV. In the  first state, the nanoparticles have gaps in their surface that absorb oxygen  ions like a sponge. When cerium oxide III is mixed with free radicals, it  catalyzes a reaction that effectively defangs the ROS by capturing oxygen atoms  and turning into cerium oxide IV. She said cerium oxide IV particles slowly  release their captured oxygen and revert to cerium oxide III, and can break down  free radicals again and again.
Colvin said the nanoparticles’ tiny size makes them effective  scavengers of oxygen.
“The smaller the particles, the more surface area they have  available to capture free radicals,” Colvin said. “A gram of these nanoparticles  can have the surface area of a football field, and that provides a lot of space  to absorb oxygen.”
None of the cerium oxide particles made before Rice tackled the  problem were stable enough to be used in biological settings, she said. “We  created uniform particles whose surfaces are really well-defined, and we found a  water-free production method to maximize the surface gaps available for oxygen  scavenging.”
Colvin said it’s relatively simple to add a polymer coating to  the 3.8-nanometer spheres. The coating is thin enough to let oxygen pass through  to the particle, but robust enough to protect it through many cycles of ROS  absorption.
In testing with hydrogen peroxide, a strong oxidizing agent, the  researchers found their most effective cerium oxide III nanoparticles performed  nine times better than a common antioxidant, Trolox, at first exposure, and held  up well through 20 redox cycles.
“The next logical step for us is to do some passive targeting,”  Colvin said. “For that, we plan to attach antibodies to the surface of the  nanoparticles so they will be attracted to particular cell types, and we will  evaluate these modified particles in more realistic biological settings.”
Colvin is most excited by the potential to help cancer patients  undergoing radiation therapy.
“Existing radioprotectants have to be given in incredibly high  doses,” she said. “They have their own side effects, and there are not a lot of  great options.”
She said a self-renewing antioxidant that can stay in place to  protect organs would have clear benefits over toxic radioprotectants that must  be eliminated from the body before they damage good tissue.
“Probably the neatest thing about this is that so much of  nanomedicine has been about exploiting the magnetic and optical properties of  nanomaterials, and we have great examples of that at Rice,” Colvin said. “But  the special properties of nanoparticles have rarely been leveraged in medical  applications.
“What I like about this work is that it opens a part of  nanochemistry — namely catalysis — to the medical world. Cerium III and IV are  electron shuttles that have broad applications if we can make the chemistry  accessible in a biological setting.
“And of all things, this humble material comes from a catalytic  converter,” she said.
Source: Rice University

Read more: http://www.nanowerk.com/news2/newsid=32746.php#!#ixzz2hunWfcKv

Making Inorganic Solar Cells with an Airbrush Spray


 

Nano Particles for Steel 324x182(Nanowerk Spotlight) There is currently a tremendous  amount of interest in the solution processing of inorganic materials. Low cost,  large area deposition of inorganic materials could revolutionize the fabrication  of solar cells, LEDs, and photodetectors. The use of inorganic nanocrystals to  form these structures is an attractive route as the ligand shell that surrounds  the inorganic core allows them to be manipulated and deposited using organic  solvents.

The most common methods currently used for film formation are  spin coating and dip coating, which provide uniform thin films but limit the  geometry of the substrate used in the process. The same nanocrystal solutions  used in these procedures can also be sprayed using an airbrush, enabling larger  areas and multiple substrates to be covered much more rapidly.

The trade-off is  the roughness and uniformity of the film, both of which can be substantially  higher.    Reporting their findings in a recent online edition of ACS  Applied Materials & Interfaces (“Inorganic Photovoltaic Devices Fabricated Using  Nanocrystal Spray Deposition”), researchers have now attempted to quantify  these differences for a single-layer solar cell structure, and found the main  difference to be a reduction in the open circuit voltage of the device.            deposited films of CdTe nanocrystals SEM  images of the top surface of the deposited films following deposition and  sintering, showing (a) CdTe spin coated and (b) CdTe spray coated. The scale bar  in both images represents 200 nm. (Reprinted with permission from American  Chemical Society)

“Our work was motivated by a desire to coat larger substrate  areas more efficiently,” Edward Foos, a research scientists in the Materials  Synthesis and Processing Section of the Chemistry Division at the Naval  Research Laboratory, and first author of the paper, tells Nanowerk. “Our initial  work indicated that if the layers were thick enough to cover the substrate  completely and avoid pinhole formation that would lead to shorting of the  device, then the increased surface roughness might be tolerable.”

He adds that this is the first time the impact of this surface  roughness on the performance characteristics has been directly compared for  these types of devices.

The team prepared single-layer Schottky-barrier solar cells  using spray deposition of inorganic (CdTe) nanocrystals with an airbrush. The  spray deposition results in a rougher film morphology that manifests itself as a  2 orders of magnitude higher saturation current density compared to spin  coating.   “We’re currently working to improve the spray coating process to  improve the layer uniformity,” says Foos. “If the surface roughness can be  reduced, then the overall device performance should increase.”   The team is confident that further optimization of the spray  process to reduce this surface roughness and limit the Voc suppression should be possible and eventually lead  to comparable performances between the two deposition techniques.   “Importantly” Foos points out, “the spray-coating process  enables larger areas to be covered more efficiently, reducing waste of the  active layer components, while enabling deposition on asymmetric substrates.

These advantages should be of substantial interest as inorganic  nanocrystal-based solar cells become increasingly competitive as  third-generation devices.”   The team’s next step will be the fabrication of more complex  device architectures that incorporate multiple solution processed layers. These  structures will have an even smaller tolerance for variation. In addition, the  deposition chemistry used must not interfere with the material applied in the  previous step.

By Michael Berger. Copyright © Nanowerk

Read more: http://www.nanowerk.com/spotlight/spotid=32458.php#ixzz2fyNZ5tzG

 

Nanotechnology Today – Fuel Cells, Buckyballs and Carbon Nanotubes


Nanotubes images 

To celebrate the 25th anniversary of National Chemistry Week, we visited the Maryland Nanocenter at the University of Maryland (UMD) to check out the latest research in nanotechnology — this year’s theme for NCW.

Three UMD researchers explain how their work in the nano-scale could lead to better fuel cells, solar cells, cancer treatments and super strong materials made from carbon nanotubes. Check out the video for a first hand look at the exciting applications of nanotechnology available today, and those that are just around the corner.

Drs. Eichhorn and Reutt-Robey at the University of Maryland ‘illuminate’ for us some of the current nano-technology being developed for commercial applications.


Video by Kirk Zamieroski Produced by the American Chemical Society

 

 

NANOTECHNOLOGY – Photons to Electricity Nano Based Solar Cells


longpredicte“Dr. Sargent provides us with a very detailed presentation on integrating ‘nanotechnology’ and photovoltaics. It is well recognized the ‘solar energy model’ will require advancements to lower manufacturing (production) costs and …

… “harvest” with greater efficiencies the available (and abundant) renewable source of energy from our sun.”  –  GenesisNanoTechnology

 

 

Published on Jul  9, 2013 

What is Nanotechnology? A basic definition: Nanotechnology is the engineering of functional systems at the molecular scale. This covers both current work and concepts that are more advanced. In its original sense, ‘nanotechnology’ refers to the projected ability to construct items from the bottom up, using techniques and tools being developed today to make complete, high performance products.

Nanotechnology (sometimes shortened to “nanotech”) is the manipulation of matter on an atomic and molecular scale. The earliest, widespread description of nanotechnology referred to the particular technological goal of precisely manipulating atoms and molecules for fabrication of macroscale products, also now referred to as molecular nanotechnology.

 

A more generalized description of nanotechnology was subsequently established by the National Nanotechnology Initiative, which defines nanotechnology as the manipulation of matter with at least one dimension sized from 1 to 100 nanometers.

This definition reflects the fact that quantum mechanical effects are important at this quantum-realm scale, and so the definition shifted from a particular technological goal to a research category inclusive of all types of research and technologies that deal with the special properties of matter that occur below the given size threshold.

 

It is therefore common to see the plural form “nanotechnologies” as well as “nanoscale technologies” to refer to the broad range of research and applications whose common trait is size. Because of the variety of potential applications (including industrial and military), governments have invested billions of dollars in nanotechnology research. Through its National Nanotechnology Initiative, the USA has invested 3.7 billion dollars. The European Union has invested 1.2 billion and Japan 750 million dollars

 

Inexpensive, Flexible Solar Cells: Rice & Penn State Collaborate


QDOTS imagesCAKXSY1K 8(Phys.org) —Work by a team of chemical engineers at Penn State and Rice University may lead to a new class of inexpensive organic solar cells.
chemicalengi

Work by a research team at Penn State and Rice University could lead to the development of flexible solar cells. The engineers’ technique centers on control of the nanostructure and morphology to create organic solar cells made of block polymers. Credit: Curtis Chan

Most solar cells today are inorganic and made of . The problem with these, Gomez explained, is that inorganic solar cells tend to be expensive, rigid and relatively inefficient when it comes to converting sunlight into electricity.

But offer an intriguing alternative that’s flexible and potentially less expensive.

Not many organic solar cells currently exist. He said, “There are a bunch of prototypes floating around. You see them in places like in solar-powered laptop bags and on the top of some bus depots.”

The problem is that the bulk of organic solar cells employ fullerene acceptors—a carbon-based molecule that’s extremely difficult to scale up for mass production.

Gomez’s approach skips the fullerene acceptor altogether and seeks to combine

The idea of utilizing molecular self-assembly for solar cells isn’t new, but Gomez said, “It’s not been well executed.”

He continued, “It’s like trying to mix oil and water.” The issue is that weak and disorder at junctions of different organic materials limited the performance and stability of previous organic solar cells.

But by controlling the and morphology, the team essentially redesigned the molecules to link together in a better way.

The engineers were able to control the donor-acceptor  through microphase-separated conjugated block copolymers.

“We have not only demonstrated control of the microstructure, but also control of the interface responsible for the initial steps in charge photogeneration in a way never achieved before,” Gomez said.

The result, which was detailed in a recent issue of the American Chemical Society‘s Nano Letters journal, is an organic solar cell made of that’s three percent efficient.

The team included Penn State chemical engineering graduate student Changhe Guo; undergraduate student Matt Witman; Rafael Verduzco, the Louis Owen Assistant Professor of Chemical and Biomolecular Engineering at Rice University; Joseph Strzalka, research scientist at Argonne National Laboratory; and research scientists Cheng Wang and Alexander Hexemer of Lawrence Berkeley National Laboratory.

Though the team’s prototype is not as efficient as some solar cells that are commercially available, Gomez explained the work shows flexible organic solar cells are indeed possible.

“Our cells right now don’t capture a lot of light. We need to look back and redesign the molecule. We think we can do better than 3 percent,” he said.

Read more at: http://phys.org/news/2013-08-chemical-inexpensive-flexible-solar-cells.html#jCpmolecules in a solution.

Nano-storage wires


(QDOTS imagesCAKXSY1K 8Nanowerk Spotlight) Nanowires are considered a major  building block for future nanotechnology devices, with great potential for  applications in transistors, solar cells, lasers, sensors, etc. (see for instance: “Nanowires  for the electronics and optoelectronics of the future” and “Nanotechnology explained:  Nanowires and nanotubes”).

Now, for the first time, nanotechnology researchers have  utilized nanowires as a ‘storage’ device for biochemical species such as ATP.   Led by Seunghun Hong, a professor of physics, biophysics and chemical  biology at Seoul National University, the team developed a new nanowire  structure – which they named ‘nano-storage wire’ – which can store and release  biomolecules.

Reporting their findings in the July 16, 2013 online edition of  ACS Nano (“Nano-Storage Wires”), Hong’s group demonstrated  that their nano-storage wire structure can be deposited onto virtually any  substrate to build nanostorage devices for the real-time controlled release of  biochemical molecules upon the application of electrical stimuli.

“Our nano-storage wires are multisegmented nanowires comprised  of three segments and each segment plays a role in extending the applications of  the nanowire,” Hong explains to Nanowerk: “1) the conducting polymer segment  stores biomolecules; 2) the nickel segment allows the utilization of magnetic  fields to drive the nanowires and place them onto a specific location for device  applications; and 3) the gold segment enables a good electrical contact between the deposited nano-storage  wires and the electrodes. The polymer segment is utilized for the controlled  release of ATP molecules. The nickel segment enables the magnetic localization  of nano-storage wires, while the gold segment provides a good electrical contact with electrodes.”

nano-storage wire Left:  Schematics of a nano-storage wire. Right: SEM image of a single nano-storage  wire. The dark, intermediate, and bright regions represent PPy-ATP (conducting  polymer with ATP molecules), nickel, and gold segments, respectively. (Images:  Dr. Seunghun Hong, Seoul National University)    The released biomolecules from such a nanowire-storage system  can be used for instance to control the activity of biosystems. As a proof of concept, the researchers stored  ATP in their nano-storage wires and released it by electrical stimuli, which  activated the motion of motor protein systems. The team also demonstrated flexible nanostorage devices. Here, nano-storage wires were driven by magnetic  fields and deposited onto nickel/gold films on a transparent and flexible  polyimide film. The device  transmitted some light, and it can be easily bent. They also showed that the nanowires could be deposited onto  curved surfaces such as the sharp end of a micropipet.       

     nano-storage wires deposited on tip of a micropipette

SEM  image of nano-storage wires deposited on a micropipet. (Reprinted with  permission from American Chemical Society)   

“Such probe-shaped storage devices can be used for the delivery  of chemicals to individual cells through a direct injection,” says Hong.  “Basically, our results show that nano-storage wires are quite versatile  structures and we  can deposit them onto virtually any structure to create nanoscale devices for  the controlled release of biochemical materials.”

“Nano-storage wires will allow the fabrication of advanced  biochips which can activate or deactivate the activities of biosystems in real  time,” Hong points out. “The activation and deactivation of biosystems such as  biomotors, are controlled by specific biomolecules. In our method, we can  selectively control the biomolecular activities related with ATP or any released  chemical species while leaving other biomolecular activities unaltered.”

Having demonstrated the storage of ATP, the team is now planning  to store other  biomolecules in our nano-storage wires. Examples are drugs to control the  activity of cells and tissues, enzymes to activate specific signal pathways in  biosystems etc. “Eventually, we would like to build an advanced biochip which  can be utilized to control the activities of desired biosystems in real-time,” says Hong.

By Michael Berger. Copyright © Nanowerk

Read more: http://www.nanowerk.com/spotlight/spotid=31619.php#ixzz2buibAVQY

Tumor Targeting platform with Nanoghosts


By Marcelle Machluf, Associate Professor, The  Faculty of Biotechnology & Food Engineering, Technion – Israel Institute of  Technology, Haifa, Israel.

 

nanomanufacturing-2(Nanowerk Spotlight) The field of drug discovery is  growing at a remarkable pace, leading to the development of many new drugs, most  of which are generally more potent than their predecessors, yet suffer from poor  solubility and/or high toxicities.

Targeted drug-delivery vehicles (e.g.,  liposomes, nano-particles) have often been proposed in an effort to reduce the  side effects of such drugs and improve their overall efficacy for treating  genetic, viral and malignant diseases.   Three main considerations must be addressed when designing any  such delivery system: It should be biocompatible; bioavailable; and highly  selective to its specific target.

Targeting may be improved by conjugating drug carrying vehicles  with targeting moieties that substantially improve their selectivity. For  example, antibodies, proteins etc. have been incorporated into nano-sized  drug-carriers made from polymeric particles, micelles or liposomes, yet their  relatively short circulation time and the complexity of their production render  them too costly and inefficient.

The need for drug delivery vehicles is particularly stressed in  cancer treatment, where high doses of toxic drugs are often required.  Passively-targeted drug-loaded vehicles are still the predominantly used  delivery systems for cancer therapy. Because of their nano-size and physical  properties, such systems were shown to achieve extended circulation times, and  retention in the tumor microenvironment—owing to the Enhanced Permeability and  Retention (EPR) effect of tumor vasculature and microenvironment.

These systems,  nonetheless, are limited by tumor vascularization and permeability that are  largely dependent on the stage of the malignancy and tumor type. Consequently,  active targeting vehicles, once a promising therapeutic approach, have almost  exhausted their potential, particularly in the area of cancer therapy where such  solutions are desperately needed.

In our recent paper (“Reconstructed Stem Cell Nanoghosts: A Natural Tumor  Targeting Platform”) we report on a novel targeted drug-delivery vehicle for  cancer therapy, which can selectively target the tumor niche while delivering an  array of therapeutic agents.   This targeting platform is based on unique vesicles  (‘nanoghosts’) that are produced, for the first time, from intact cell membranes  of stem cells with inherent homing abilities, and which may be loaded with  different therapeutics.

     Binding of nanoghosts to cells Binding of nanoghosts (white arrow) to PC3 cells; cell, green (GFP);  nucleolus, blue (DAPI) evaluated using confocal microscopy over short (3 h)  incubation times. (Reprinted with permission from American Chemical Society)  

We have shown that such vesicles, encompassing the cell surface  molecules and preserving the targeting mechanism of the cells from which they  were made, can outperform conventional delivery systems based on liposomes or  nanoparticles.   These vesicles leverage the benefits related to the size, and  chemical and physical properties of nano-liposomes, allowing them to efficiently  entrap various hydrophilic and hydrophobic drugs, and be administered through  different routes while exhibiting versatile and controllable release profiles.

The prior art pertaining to the design of this unique and novel drug-delivery  platform is drawn from and associated with the production and utilization of  cell-derived vesicles, and the inherent tumor-targeting abilities of mesenchymal  stem cells (MSCs).   A similar therapeutic effect, to what we have achieved, was  previously demonstrated for prostate cancer, using monoclonal antibodies against  N-cadherin, which is highly expressed in castration-resistant prostate cancer;  however, it requires more frequent and higher dosing.

Our therapeutic outcome is comparable to that demonstrated by De  Marra et al. (“New self-assembly nanoparticles and stealth  liposomes for the delivery of zoledronic acid: a comparative study”) who  used no less than three administrations per week of liposomes encapsulating  Zoledronic acid and exceeded the effect achieved by a weekly administration of  an imatinib–mitoxantrone liposomal formulation.

The efficiency of our delivery system is even more compelling in  light of the results reported by Srivastava et al. (“Effects of sequential treatments with chemotherapeutic drugs  followed by TRAIL on prostate cancer in vitro and in vivo”), which  demonstrated no inhibition of tumor growth after two weeks and as many as four  IV administrations of similar quantities of free sTRAIL. The efficacy of our  system also exceeded that of previously reported liposomal formulations  containing sTRAIL tested on glioblastoma and lung cancer.

Till now, nanoghosts made from mammalian cells have been used to  study cell membranes and were utilized for cancer immunotherapy but have never  been tested as targeted drug-delivery vehicles. Recently, we reported a novel  concept describing a targeted drug-delivery system based on nanoghosts, which  were prepared from the outer cell membranes of a non-human cells engineered to  express the human receptor (CCR5) of a viral ligand (gp120) found on the surface  of HIV-infected cells (“Cell derived liposomes expressing CCR5 as a new  targeted drug-delivery system for HIV infected cells”).

Drug-loaded  nanoghosts selectively targeted HIV-infected cells in vitro, achieving  over 60% reduction in their viability compared to empty nanoghosts, free drug,  or nanoghosts applied on control uninfected cells that were not affected at all.   This intrinsically-targeted system, which does not entail the  elaborate production of targeting molecules and their incorporation into passive  vehicles, represents a simpler and more clinically relevant approach than  existing particulate drug-delivery vehicles.

Our success in using nanoghosts to target HIV-infected cells has  prompted us to devise a more sophisticated universal and non-immunogenic  delivery platform, in which the nanoghosts will be produced from stem cells that  are known to naturally target various tumors.   Insights gained from this work may pave the way for new research  utilizing nanoghosts’ inherent targeting to treat not only tumors but also sites  of inflammations, wound healing, and trauma.

The knowledge accumulated on the entrapment of diverse drugs can  facilitate the loading of nanoghosts with nucleic acid (DNA, siRNA etc.) for  gene therapy.   Nanoghosts loaded with MRI contrast agents (Indocyanine or  magnetite nano-crystals) can open unique research avenues in imaging and  diagnosis. Their small size and specific targeting abilities may enable the  nanoghosts to freely travel in the body possibly detecting small and  sub-metastatic cancer nuclei and lesions, which are otherwise undetectable using  conventional methodologies.

Owing to MSCs natural role in regenerative medicine, nanoghosts  can be also investigated in tissue engineering applications for delivering  growth factors for regenerating tissues.   Finally, MSCs can be engineered to express additional targeting  molecules and used to treat other diseases manifested by the expression of  unique targetable ligands.

This work was conducted by PhD students Naama Ester  Toledano-Furman, Yael Lupu-Haber, Limor Kaneti, and the Lab manager Dr. Tomer  Bronshtein.

By Marcelle Machluf, Associate Professor, The  Faculty of Biotechnology & Food Engineering, Technion – Israel Institute of  Technology, Haifa, Israel.

Read more: http://www.nanowerk.com/spotlight/spotid=31548.php#ixzz2apeCNQzx

Nanowires: Major Building-block for Nanotechnology Devices: Transistors, Solar Cells, Lasers and More


By Michael Berger. Copyright © Nanowerk

201306047919620(Nanowerk Spotlight) Nanowires are considered a major  building block for future nanotechnology devices, with great potential for  applications in transistors, solar cells, lasers, sensors, etc.

 

*** Read articles explaining how ‘nanowires and nanotubes’ differ from other quantum materials, such as quantum dots, and their potential applications here:

http://www.nanowerk.com/news2/newsid=29945.php

http://www.nanowerk.com/news/newsid=16857.php

 

Now, for the first time, nanotechnology researchers have  utilized nanowires as a ‘storage’ device for biochemical species such as ATP.   Led by Seunghun Hong, a professor of physics, biophysics and chemical  biology at Seoul National University, the team developed a new nanowire  structure – which they named ‘nano-storage wire’ – which can store and release  biomolecules.

Reporting their findings in the July 16, 2013 online edition of  ACS Nano (“Nano-Storage Wires”), Hong’s group demonstrated  that their nano-storage wire structure can be deposited onto virtually any  substrate to build nanostorage devices for the real-time controlled release of  biochemical molecules upon the application of electrical stimuli.

“Our nano-storage wires are multisegmented nanowires comprised  of three segments and each segment plays a role in extending the applications of  the nanowire,” Hong explains to Nanowerk: “1) the conducting polymer segment  stores biomolecules; 2) the nickel segment allows the utilization of magnetic  fields to drive the nanowires and place them onto a specific location for device  applications; and 3) the gold segment enables a good electrical contact between  the deposited nano-storage wires and the electrodes. The polymer segment is  utilized for the controlled release of ATP molecules. The nickel segment enables  the magnetic localization of nano-storage wires, while the gold segment provides  a good electrical contact with electrodes.”

  nano-storage wire Left:  Schematics of a nano-storage wire. Right: SEM image of a single nano-storage  wire. The dark, intermediate, and bright regions represent PPy-ATP (conducting  polymer with ATP molecules), nickel, and gold segments, respectively. (Images:  Dr. Seunghun Hong, Seoul National University)   

The released biomolecules from such a nanowire-storage system  can be used for instance to control the activity of biosystems. As a proof of  concept, the researchers stored ATP in their nano-storage wires and released it  by electrical stimuli, which activated the motion of motor protein systems.   The team also demonstrated flexible nanostorage devices. Here,  nano-storage wires were driven by magnetic fields and deposited onto nickel/gold  films on a transparent and flexible polyimide film. The device transmitted some  light, and it can be easily bent.   They also showed that the nanowires could be deposited onto  curved surfaces such as the sharp end of a micropipet.

nano-storage wires deposited on tip of a micropipette

SEM  image of nano-storage wires deposited on a micropipet. (Reprinted with  permission from American Chemical Society)   

“Such probe-shaped storage devices can be used for the delivery  of chemicals to individual cells through a direct injection,” says Hong.  “Basically, our results show that nano-storage wires are quite versatile  structures and we can deposit them onto virtually any structure to create  nanoscale devices for the controlled release of biochemical materials.”   “Nano-storage wires will allow the fabrication of advanced  biochips which can activate or deactivate the activities of biosystems in real  time,” Hong points out. “The activation and deactivation of biosystems such as  biomotors, are controlled by specific biomolecules.

In our method, we can  selectively control the biomolecular activities related with ATP or any released  chemical species while leaving other biomolecular activities unaltered.”   Having demonstrated the storage of ATP, the team is now planning  to store other biomolecules in our nano-storage wires. Examples are drugs to  control the activity of cells and tissues, enzymes to activate specific signal  pathways in biosystems etc.   “Eventually, we would like to build an advanced biochip which  can be utilized to control the activities of desired biosystems in real-time,”  says Hong.

By Michael Berger. Copyright © Nanowerk

Read more: http://www.nanowerk.com/spotlight/spotid=31619.php#ixzz2apWtDi34