Solar power captured in fuel


19 October 2012

RMIT UNIVERSITY
TUESDAY, 23 OCTOBER 2012

Solar power captured in fuel

 

 

 

 

 

 

Note To Readers: Our Comments: An abundant FREE source of energy … that is limitless … and GREEN to boot! Quoting from the news release:

” … “Our future scientific goal is to establish a solar water splitting system operated only by abundant sunlight and sea water,” Associate Professor Tachibana remarked. “Fortunately these resources are freely available on this blue planet.

“The key to improving efficiency will be in the development of new “nano-materials” (microscopically small components), along with efficient control of charge transfer reaction processes, and improvement to the structure of devices.”

Cheers! – BWH

It has long been a dream of scientists to use solar energy to produce chemicals which could be stored and later used to create electricity or fuels.

A recent scientific breakthrough is providing hope that this may soon be possible.

The development would offer many benefits, including the ability to store chemicals until needed – current solar power technology has difficulties in this area.

In the laboratory, a new technology mimics photosynthesis, the process used by plants, by combining sunlight and water in such a way that promises storable fuels.

The “solar to chemical energy conversion” process is outlined in an article just published in a prominent journal, Nature Photonics, authored by RMIT University researcher Associate Professor Yasuhiro Tachibana, from the School of Aerospace, Mechanical and Manufacturing Engineering.

Inspired by photosynthesis, in which oxygen and carbohydrates are produced from water and carbon dioxide, the newly developed technology emulates this process using man-made materials.

According to Associate Professor Tachibana, it remains a challenge to construct a device capable of producing molecular fuels like hydrogen at a scale and cost able to compete with fossil fuels.

The key to improving efficiency will be in the development of new “nano-materials” (microscopically small components), along with efficient control of charge transfer reaction processes, and improvement to the structure of devices.

Recent developments in the field of nanotechnology have been leading to promising improvements in cost and effectiveness of the conversion process, Associate Professor Tachibana said.

“Our future scientific goal is to establish a solar water splitting system operated only by abundant sunlight and sea water,” Associate Professor Tachibana remarked.

“Fortunately these resources are freely available on this blue planet.”

Professor Xinghuo Yu, Director of RMIT’s Platform Technologies Research Institute, said the latest research was significant, but challenges remained in how to translate laboratory-scale academic research into a practical, economically viable technology.

In addition to using solar energy, other commercially available renewable energy sources like wind and tidal power could also conceivably be applied, Professor Yu said.

Associate Professor Tachibana’s review paper was published in the August 2012 edition of Nature Photonics, world-renowned as a pre-eminent platform for publication of international research in photonics.

Editor’s Note: Original news release can be found here.

 

Shape may play an important role in nanoparticle-based therapeutics


 

Credits: Wei Qu, Northwestern University, simulation cartoons; Xuan Jiang, Johns Hopkins University, microscopic images.

 

“We now can predict precisely how to choose the nanoparticle components if one wants to obtain a certain shape. The use of computer models allowed Luijten’s team to mimic traditional lab experiments at a far faster pace.”

 

Nanoparticle-based research remains at the forefront of nanoscale approaches to targeted drug delivery and gene therapy (see related posts highlighting achievements in targeting specificity and enhanced delivery owed to high nanoparticle surface area). Recently reprintedby KurzweilAI.net, a news release from Johns Hopkins University entitled“Scientists Discover That Shape Matters in DNA Nanoparticle Therapy” describes the new findings, in which researchers from JHU and Northwestern University developed a set of DNA-copolymer nanoparticles that differ significantly in shape and in transfection efficiency.

The shapes were achieved first by mixing solutions of DNA and copolymer under varying solvent polarity conditions, allowing the micellar nanoparticles to adopt preferred configurations. The resulting shapes were similar to those observed in viral particles, with a worm-like shape predominating at higher polarities (i.e. higher water ratios). A reversible disulfide crosslinking method was then used to replicate the shapes under aqueous conditions, using cryo-TEM imaging to verify shape fidelity.

Notably, molecular dynamics simulations were conducted to model the shape transitions, providing experimentalists with time-saving predictive power.

“Our computer simulations and theoretical model have provided a mechanistic understanding, identifying what is responsible for this shape change,” Luijten said. “We now can predict precisely how to choose the nanoparticle components if one wants to obtain a certain shape. The use of computer models allowed Luijten’s team to mimic traditional lab experiments at a far faster pace.

In rat liver, the worm-like shapes, with average length of 581 nm, showed the highest gene expression, over 1,600-fold higher than that observed for spherical shapes of approximately 40 nm diameter.

While the variation in particle size may have an impact, co-corresponding author Hai-Quan Mao of JHU notes that the range of particles are similar in volume and weight, with fixed amounts of DNA. The full study, published in Advanced Materials, can be viewed in advance on line.

Researchers Create ‘Nanoflowers’ for Energy Storage, Solar Cells


Release Date: 10.11.2012

Researchers from North Carolina State University have created flower-like structures out of germanium sulfide (GeS) – a semiconductor material – that have extremely thin petals with an enormous surface area. The GeS flower holds promise for next-generation energy storage devices and solar cells.

 

 

 

 

 

Matt Shipman |

Dr. Linyou Cao |

The GeS “nanoflowers” have petals only 20-30 nanometers thick, and provide a large surface area in a small amount of space. (Click to enlarge image.)

“Creating these GeS nanoflowers is exciting because it gives us a huge surface area in a small amount of space,” says Dr. Linyou Cao, an assistant professor of materials science and engineering at NC State and co-author of a paper on the research. “This could significantly increase the capacity of lithium-ion batteries, for instance, since the thinner structure with larger surface area can hold more lithium ions. By the same token, this GeS flower structure could lead to increased capacity for supercapacitors, which are also used for energy storage.”

To create the flower structures, researchers first heat GeS powder in a furnace until it begins to vaporize. The vapor is then blown into a cooler region of the furnace, where the GeS settles out of the air into a layered sheet that is only 20 to 30 nanometers thick, and up to 100 micrometers long. As additional layers are added, the sheets branch out from one another, creating a floral pattern similar to a marigold or carnation.

“To get this structure, it is very important to control the flow of the GeS vapor,” Cao says, “so that it has time to spread out in layers, rather than aggregating into clumps.”

GeS is similar to materials such as graphite, which settle into neat layers or sheets. However, GeS is very different from graphite in that its atomic structure makes it very good at absorbing solar energy and converting it into useable power. This makes it attractive for use in solar cells, particularly since GeS is relatively inexpensive and non-toxic. Many of the materials currently used in solar cells are both expensive and extremely toxic.

The paper, “Role of Boundary Layer Diffusion in Vapor Deposition Growth of Chalcogenide Nanosheets: The Case of GeS,” is published online in the journal ACS Nano. The paper was co-authored by Cao; Dr. Chun Li, a former postdoctoral researcher at NC State, now a professor at the University of Electronic Science and Technology of China; Liang Huang, a former visiting Ph.D. student at NC State; Gayatri Pongur Snigdha, a former undergraduate student at NC State; and Yifei Yu, a Ph.D. student at NC State. The work was supported by the U.S. Army Research Office.

-shipman-

Note to Editors: The study abstract follows.

“Role of Boundary Layer Diffusion in Vapor Deposition Growth of Chalcogenide Nanosheets: The Case of GeS”

Authors: Chun Li, Liang Huang, Gayatri Pongur Snigdha and Linyou Cao, North Carolina State University

Published: Online, ACS Nano

Abstract: We report a synthesis of single crystalline two-dimensional (2D) GeS nanosheets using vapor deposition processes, and show that the growth behavior of the nanosheet is substantially different from those of other nanomaterials and thin films grown by vapor depositions. The nanosheet growth is subject to strong influences of the diffusion of source materials through the boundary layer of gas flows. This boundary layer diffusion is found to be the rate-determining step of the growth under typical experimental conditions, evidenced by a substantial dependence of the nanosheet’s size on diffusion fluxes. We also find that high quality GeS nanosheets can only grow in the diffusion-limited regime, as the crystalline quality substantially deteriorates when the rate-determining step is changed away from the boundary layer diffusion. We establish a simple model to analyze the diffusion dynamics in experiments. Our analysis uncovers an intuitive correlation of diffusion flux with the partial pressure of source materials, the flow rate of carrier gas, and the total pressure in synthetic setup. The observed significant role of boundary layer diffusions in the growth is unique for nanosheets. It may be correlated to the high growth rate of GeS nanosheets, ~3-5 [micrometer]/min, which is one order of magnitude higher than other nanomaterials (such as nanowires) and thin films. This fundamental understanding on the effect of boundary layer diffusions may generally apply to other chalcogenide nanosheets that can grow rapidly. It can provide useful guidance for the development of general paradigms to control the synthesis of nanosheets.

Light might prompt graphene devices on demand


MIKE WILLIAMS

 – OCTOBER 10, 2012

Rice University researchers find plasmonics show promise for optically induced electronics

Rice University researchers are doping graphene with light in a way that could lead to the more efficient design and manufacture of electronics, as well as novel security and cryptography devices.

Graphene circuitry

Nanoscale plasmonic antennas called nonamers placed on graphene have the potential to create electronic circuits by hitting them with light at particular frequencies, according to researchers at Rice University. The positively and negatively doped graphene can be prompted to form phantom circuits on demand.

Manufacturers chemically dope silicon to adjust its semiconducting properties. But the breakthrough reported in the American Chemical Society journal ACS Nano details a novel concept: plasmon-induced doping of graphene, the ultrastrong, highly conductive, single-atom-thick form of carbon.

That could facilitate the instant creation of circuitry – optically induced electronics – on graphene patterned with plasmonic antennas that can manipulate light and inject electrons into the material to affect its conductivity.

The research incorporates both theoretical and experimental work to show the potential for making simple, graphene-based diodes and transistors on demand. The work was done by Rice scientists Naomi Halas, Stanley C. Moore Professor in Electrical and Computer Engineering, a professor of biomedical engineering, chemistry, physics and astronomy and director of the Laboratory for Nanophotonics; and Peter Nordlander, professor of physics and astronomy and of electrical and computer engineering; physicist Frank Koppens of the Institute of Photonic Sciences in Barcelona, Spain; lead author Zheyu Fang, a postdoctoral researcher at Rice; and their colleagues.

“One of the major justifications for graphene research has always been about the electronics,” Nordlander said. “People who know silicon understand that electronics are only possible because it can be p- and n-doped (positive and negative), and we’re learning how this can be done on graphene.

“The doping of graphene is a key parameter in the development of graphene electronics,” he said. “You can’t buy graphene-based electronic devices now, but there’s no question that manufacturers are putting a lot of effort into it because of its potential high speed.”

Researchers have investigated many strategies for doping graphene, including attaching organic or metallic molecules to its hexagonal lattice. Making it selectively – and reversibly – amenable to doping would be like having a graphene blackboard upon which circuitry can be written and erased at will, depending on the colors, angles or polarization of the light hitting it.

Nonamers

Nonamers in the drawings at top and in the photos at bottom are arrays of nine gold nanoparticles deposited on graphene and tuned to particular frequencies of light. When illuminated, the plasmonic particles pump electrons into the graphene, according to researchers at Rice University who say the technology may lead to the creation of on-demand circuitry for electronic devices.

The ability to attach plasmonic nanoantennas to graphene affords just such a possibility. Halas and Nordlander have considerable expertise in the manipulation of the quasiparticles known as plasmons, which can be prompted to oscillate on the surface of a metal. In earlier work, they succeeded in depositing plasmonic nanoparticles that act as photodetectors on graphene.

These metal particles don’t so much reflect light as redirect its energy; the plasmons that flow in waves across the surface when excited emit light or can create “hot electrons” at particular, controllable wavelengths. Adjacent plasmonic particles can interact with each other in ways that are also tunable.

That effect can easily be seen in graphs of the material’s Fano resonance, where the plasmonic antennas called nonamers, each a little more than 300 nanometers across, clearly scatter light from a laser source except at the specific wavelength to which the antennas are tuned. For the Rice experiment, those nonamers – eight nanoscale gold discs arrayed around one larger disc – were deposited onto a sheet of graphene through electron-beam lithography. The nonamers were tuned to scatter light between 500 and 1,250 nanometers, but with destructive interference at about 825 nanometers.

At the point of destructive interference, most of the incident light energy is converted into hot electrons that transfer directly to the graphene sheet and change portions of the sheet from a conductor to an n-doped semiconductor.

Arrays of antennas can be affected in various ways and allow phantom circuits to materialize under the influence of light. “Quantum dot and plasmonic nanoparticle antennas can be tuned to respond to pretty much any color in the visible spectrum,” Nordlander said. “We can even tune them to different polarization states, or the shape of a wavefront.

“That’s the magic of plasmonics,” he said. “We can tune the plasmon resonance any way we want. In this case, we decided to do it at 825 nanometers because that is in the middle of the spectral range of our available light sources. We wanted to know that we could send light at different colors and see no effect, and at that particular color see a big effect.”

Nordlander said he foresees a day when, instead of using a key, people might wave a flashlight in a particular pattern to open a door by inducing the circuitry of a lock on demand. “Opening a lock becomes a direct event because we are sending the right lights toward the substrate and creating the integrated circuits. It will only answer to my call,” he said.

Rice co-authors of the paper are graduate students Yumin Wang and Andrea Schlather, research scientist Zheng Liu, and Pulickel Ajayan, the Benjamin M. and Mary Greenwood Anderson Professor in Mechanical Engineering and Materials Science and of chemistry.

The research was supported by the Robert A. Welch Foundation, the Office of Naval Research, the Department of Defense National Security Science and Engineering Faculty Fellows program and Fundacio Cellex Barcelona.

Researchers seek way to make solar cell ultrathin, flexible


Tue, 10/09/2012 – 10:32am

Researchers at The University of Texas at Dallas are developing nanotechnology that could lead to a new platform for solar cells, one that could drive the development of lighter, flexible, and more versatile solar-powered technology than is currently available.

The National Science Foundation recently awarded a $390,000 grant to Anton Malko and Yuri Gartstein, both in the Department of Physics, and Yves Chabal in the Department of Materials Science and Engineering to further explore their research on the feasibility of ultrathin-film photovoltaic devices, which convert light from the sun into electric power.

“Traditional silicon solar cells that are commercially available are made from silicon that is a couple of hundred microns thick,” Malko says. “Our goal is to reduce that by a hundred times, down to about one micron thick, while at the same time maintaining efficiency.”

While the scale of the research objects is tiny, their impact could be substantial.

“Solar cells that are 100 microns thick are rigid and fragile,” Malko says. “At the thickness we are investigating, devices would not only be lighter, but they also become flexible. There is a large market and application niche for flexible solar cells, such as on clothing or backpacks for hikers, or in situations where you need portable sources to power electronics.”

The UT Dallas approach to building solar cells involves the use of nanosized crystal particles called quantum dots, which absorb light much better than silicon. The energy they absorb is then transferred into silicon and converted into an electric signal.

The researchers construct their experimental photovoltaic structures layer by layer, starting with an ultrathin layer of silicon, a so-called nanomembrane about one-tenth of a micron thick. On top of that, with the aid of special molecular “linkers,” layers of accurately positioned quantum dots are added.

“This is not yet an engineering project, it’s a research project,” Gartstein says. “We believe we are asking interesting scientific questions and researching concepts that might eventually lead to devices.”

Initial findings from the research were published in ACS Nano.

“The key point of our research is to characterize the way energy is transferred from the quantum dots through the layers to the silicon, as well as to determine how we might exploit those properties and optimize the arrangement of the quantum dots, the thickness of the layers and other aspects of the structure,” Malko says.

The cross-disciplinary research involves not only proficiency in experimental and theoretical physics, which Malko and Gartstein provide. Materials science and nanotechnology expertise is also crucial. A key member of the team is Oliver Seitz, a postdoctoral researcher in Chabal’s laboratory, who carried out the delicate and precisely controlled process of actually building the test structures.

“This project, conceived and initiated by Anton Malko, has been exciting at all stages of research,” says Chabal, holder of the Texas Instruments Distinguished University Chair in Nanoelectronics. “It has engaged my group into an exciting application relying on the chemical control of surfaces we have been developing.”

Gartstein adds, “This is one of those cases where the word ‘synergy’ truly applies. As a theorist, I can come up with some ideas and do some calculations, but I cannot build these things. In materials science, Seitz actually implements our joint ideas to make the physical samples. Then in Malko’s lab, ultrafast laser spectroscopy is used to physically measure the relevant processes and properties. Hue Minh Nguyen, a physics graduate student, contributed tremendously to this effort.

“It’s been a great pleasure to work together in this atmosphere of a true collaboration,” he says.

Source: University of Texas at Dallas

Factors affecting the PK of the nanocarrier: Pharmaceutical Intelligence


Author: Tilda Barliya PhD

Title: Factors affecting the PK of the nanocarrier.

Category: Nanotechnology in drug delivery

A plethora of new products are emerging as potential therapeutic agents. This calls for detailed studies of their unique pharmacologic characteristics and mechanisms of action in humans. This review written by Caron WP et al (Zamboni’s group) provides a major overview of the factors that affect the pharmacokinetics (PK) and pharmacodynamics (PD) of nanoparticle carries in preclinical models and patients (1). I will use this article as the main source as it was so nicely written yet many other references are added within.

The disposition of carrier-mediated agents (CMAs) is dependent on the carrier and not on the parent drug, until the drug is released from the carrier into the system and includes encapsulated (the drug within or bound to the carrier), released (the active drug that gets released from the carrier), and sum total (encapsulated drug plus released drug).

After the drug has been released from its carrier, it is pharmacologically active and subjected to the same routes of metabolism and clearance (CL) as the non-carrier form of the drug (1,2).

In theory, the PK disposition of the drug after it is released from the carrier should be the same as after administration of the small-molecule or standard formulations. Therefore, the pharmacology and PK of CMAs are complex and call for comprehensive analytical studies to assess the disposition of encapsulated and released forms of the drug in plasma and tumor.

Interindividual variability in drug exposure, represented by area under the plasma concentration– time curve (AUC) of the encapsulated drug and several factor can potentially affect it:

  • Physical characteristics of the CMA (size, charge, surface modification). Figure 1
  • Host-associated characteristics such as gender and age as well as the host mononuclear phagocyte system (MPS), which is a collective term for the immune cells.

 

 

Unfortunately we are unable to provide accessible alternative text for this. If you require assistance to access this image, please contact help@nature.com or the author

Figure 1 here (=figure 3 in the original paper. ref 1) : Nanoparticle clearance and biocompatibility are dependent on various factors including physical characteristics of the carrier as well as physiologic parameters such as the mononuclear phagocyte system (MPS) (reticuloendothelial system (RES)) recognition and enhanced permeability and retention (EPR) effect. There are qualitative relationships between the independent variables, namely, particle size, particle zeta-potential (surface charge), and solubility, and the dependent variable, namely, biocompatibility. Biocompatibility, or extent of exposure (area under the plasma concentration–time curve), includes the route of uptake and clearance (shown in green as the EPR effect and renal and biliary clearance), cytotoxicity (shown in red, can represent either efficacy or toxicities/ adverse events in anticancer treatment), and MPS/RES recognition (shown in blue).

The effect on the immune cells is divided into two categories:  (i) responses to nanoparticles that are specifically modified to stimulate the immune system (e.g., vaccine carriers) and (ii) undesirable interactions and/or side-effects.

Immune cells that participate in nanoparticle uptake are circulating monocytes, platelets, leukocytes, and dendritic cells in the bloodstream (3,4).  In addition, nanoparticles can be taken up in tissues by phagocytes, e.g., by Kupffer cells in the liver, by dendritic cells in the lymph nodes, by B cells in the spleen, and by macrophages

Uptake mechanisms may occur through different pathways and can often be facilitated by the adsorption of opsonins to the nanoparticle surface

Physical characteristics:

  • Particle size: In one study of liposomes, particles that had a hydrodynamic diameter between 100 and 200 nm had a fourfold higher rate of uptake in tumors than particles <50 nm or >300 nm.
  • Surface modification: Conjugated PEG polymer onto the surface- is known to minimize opsonization and thus subsequent decreased rate of MPS uptake overall plasma exposures of drugs contained within PEGylated liposomes were six fold higher than those contained within non-PEGylated liposomes
  • Surface charge: Uncharged liposomes have lower CLs than either positively or negatively charged liposomes (probably due to reduced opsonization by MPS. rate of CL from blood was significantly higher for negatively charged particles than for uncharged particles

It can be summarized as for their rate of clearance from highest (left) to lowest (right) as:

positive>negative> neutral

Note: PEGylation can alter the alter this rate significantly for example,

Levchenko et al. showed that the negative charge on liposomes can be shielded with this physical alteration, leading to a significantly reduced rate of liver uptake and consequent prolongation of their presence in circulating blood (5).

Host characteristics

  • Age: In some cases, age-related effects on the PK of some PEGylated liposomal agents have been reported, where in younger male patients (<60) there was a higher rate of clearance of two different agents (Doxil and CDK602) compared to older patients (>60). In other words, in older age, the CL rate was lower and therefore higher AUC/dose. No relation to age was observed for female patients, in the same study.

Alterations in the PK and PD of CMAs may involve accerelated decline in immune system functioning, specifically the association between aging and the functioning of monocytes (6). In theory, there is a loss of MPS activity or function in elderly patients, and this decreases the CL of CMAs by the MPS, leading to increased drug exposures and toxicity in elderly patients. In terms of efficacy, greater age was inversely proportional to progression-free survival; however, no correlation was found between age and overall survival.

  •  Gender: In similar study to the one presented above, female patients had overall lower CL of DOXIL, IHL-305 and CDK602 compared to male patients of the same age.

The basis for the gender-related differences in the PK and PD of CMAs is unclear. It has been hypothesized that some of the differences may be attributed to the effects of sex hormones such as testosterone and estrogen on immune cell function.

Delivery of CMAs Into Tumor

Major advances in the understanding of tumor biology have led to the discovery of targeted agents that can deliver drugs to the desired site while minimizing exposure in normal tissues, thereby minimizing the associated adverse effects. Whereas conventional drugs encounter numerous obstacles en route to their target, CMAs can take advantage of a tumor’s leaky vasculature to extravasate into tissue, via the enhanced permeability and retention effect (EPR).

Note: The extend of the EPR effect is highly debated since although passive targeting through the EPR effect has been a key concept in delivering CMAs to tumors, it does not ensure uniform delivery to all regions of tumor. Furthermore, not all tumors exhibit an EPR effect, and the permeability of vessels may not be the same across any single tumor.

Active targeting may overcome these limitations. The CMAs can be enabled to bind to specific cells in a tumor by using surface attached ligands that are capable of recognizing and binding to cells of interest.

Antibody-mediated targeting has been the method of choice, other targeting strategies using nucleic acids, carbohydrates, peptides, aptamers, vitamins, and other agents are also being evaluated.

Other major points that can affect the PK disposition

  • The linearity and nonlinearity of the CLs of a drug (might be associated with the dose like with S-CKD602)(7).
  • Drug-drug interaction (single agent vs combination)
  • Body composition (Body surface area, body weight)

There are a multitude of properties of CMAs that differ from those of the active small-molecule drugs they contain. These differences lead to significant variability in the PK and PD of carrier- mediated drugs. It has been shown that physical properties, the MPS, the presence of tumors in the liver, EPRs, drug–drug interactions, age, and gender all contribute in varying degrees to the PK disposition and PD end points of CMAs in patients.

Areas of research that can aid in an understanding of how these agents should be used and how we may predict their actions in patients include pharmacogenomics, cellular function (probing the MPS), more sensitive and accurate analytical PK methods, and identification of the optimal preclinical (animal and in vitro) models.

References:

1. W P Caron, G Song, P Kumar, S Rawal and W C Zamboni.Interpatient PK and PD variability of carrier-mediated anticancer agent.  Clinical Pharmacology and Therapeutics 2012 91, 802-812 http://www.nature.com/clpt/journal/vaop/ncurrent/full/clpt201212a.html

2. Zamboni, W.C. Liposomal, nanoparticle, and conjugated formulations of anticancer agents. Clin. Cancer Res. 11, 8230–8234 (2005).

http://clincancerres.aacrjournals.org/content/11/23/8230.long

http://clincancerres.aacrjournals.org/content/11/23/8230.full.pdf+html

3. Dobrovolskaia, M.A., Aggarwal, P., Hall, J.B. & McNeil, S.E. Preclinical studies to understand nanoparticle interaction with the immune system and its potential effects on nanoparticle biodistribution. Mol. Pharm. 5, 487–495 (2008). http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2613572/

4. Dobrovolskaia, M.A. & McNeil, S.E. Immunological properties of engineered nanomaterials. Nat. Nanotechnol. 2, 469–478 (2007). http://www.ncbi.nlm.nih.gov/pubmed/18654343

5. Levchenko, T.S., Rammohan, R., Lukyanov, A.N., Whiteman, K.R. & Torchilin, V.P. Liposome clearance in mice: the effect of a separate and combined presence of surface charge and polymer coating. Int. J. Pharm. 240, 95–102 (2002). http://www.ncbi.nlm.nih.gov/pubmed/12062505

6. Lloberas, J. & Celada, A. Effect of aging on macrophage function. Exp. Gerontol. 37, 1325–1331 (2002). http://www.ncbi.nlm.nih.gov/pubmed/12559402

7. Zamboni, W.C. et al. Pharmacokinetic study of pegylated liposomal CKD-602 (S-CKD602) in patients with advanced malignancies. Clin. Pharmacol. Ther. 86, 519–526 (2009). http://www.nature.com/clpt/journal/v86/n5/abs/clpt2009141a.html

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