Advertisements
Feeds:
Posts
Comments

Archive for the ‘Materials Science & Engineering’ Category


Artificial Skin That “Feels” Temperature Changes

Reporter: Irina Robu, PhD

Engineers and scientists at California Institute of Technology (Caltech) and ETH Zurich developed an artificial skin capable of detecting temperature changes using a mechanism similar to the biological mechanism that allow snakes to sense prey through heat.  In those organs, ion channels in the cell membrane of sensory nerve fibers expand as temperature increases. This dilation allows calcium ions to flow, triggering electrical impulses.

The material used is a long chain molecule found in plant cells which gives the skin its temperature sensing capabilities. The team chose pectin because the pectin molecules in the film have a weakly bonded double-strand structure that contains calcium ions. As temperature increases, these bonds break down and the double strands “unzip,” releasing the positively charged calcium ions.

This would make pectin sensors useful for industrial applications, such as thermal sensors in consumer electronics or robotic skins to augment human-robot interactions. However, they need to change the fabrication process as that the current process leads to the presence of water which tends to bubble or evaporate at high temperatures.

Source

https://www.rdmag.com/news/2017/01/engineers-create-artificial-skin-feels-temperature-changes?cmpid=verticalcontent

Advertisements

Read Full Post »


Intelligent Implant Biomaterials

Reporter: Irina Robu, PhD

Implants are gradually being used to treat various bone defects. A key factor for long term success of implants is the proper selection of the implant biomaterial. The biologic environment does not accept completely any material so to optimize biologic performance, implants should be selected to reduce the negative biologic response while maintaining adequate function. The implanted structure must if possible stimulate new bone formation, integrate with existing tissue and lastly be resorbed by the body to enable healthy bone growth.
The EU-funded MGNIM project which tailored biodegradable magnesium implant materials focused on producing aluminum- free Mg-based material suitable for bone applications. MAGNIM produced over 20 different Mg alloys and evaluated their mechanical and structural properties. In addition, they assessed their biological interaction, more specifically their corrosion-behavior. Out of these, two of the new alloys (Mg-2Ag and Mg-10Gd) were nominated for animal trials as pilot results indicated an anti-inflammatory function of degradation products.
The two new alloys, Mg-2Ag and Mg-10Gd as well as Mg alloy WE43 were tested in-vivo for biodegradability and functionality. Screws made of these materials were inserted into the femur of rats and their degradation was monitored. Imaging and histological data from explants revealed new bone formation in the screw implant site.

Even though the project has ended, additional testing in large animal models will be carried out prior to human clinical trials. MAGNIM partners propose to optimize implant material homogeneity and surface properties.

SOURCE
http://cordis.europa.eu/result/rcn/150629_en.html

Read Full Post »


BioPrinting Basics

Curator: Larry H. Bernstein, MD, FCAP

 

 

The ABCs of 3D Bioprinting of Living Tissues, Organs   5/06/2016 

(Credit: Ozbolat Lab/Penn State University)
(Credit: Ozbolat Lab/Penn State University)

Although first originated in 2003, the world of bioprinting is still very new and ambiguous. Nevertheless, as the need for organ donation continues to increase worldwide, and organ and tissue shortages prevail, a handful of scientists have started utilizing this cutting-edge science and technology for various areas of regenerative medicine to possibly fill that organ-shortage void.

Among these scientists is Ibrahim Tarik Ozbolat, an associate professor of Engineering Science and Mechanics Department and the Huck Institutes of the Life Sciences at Penn State University, who’s been studying bioprinting and tissue engineering for years.

While Ozbolat is not the first to originate 3D bioprinting research, he’s the first one at Penn State University to spearhead the studies at Ozbolat Lab, Leading Bioprinting Research.

“Tissue engineering is a big need. Regenerative medicine, biofabrication of tissues and organs that can replace the damage or diseases is important,” Ozbolat told R&D Magazine after his seminar presentation at Interphex last week in New York City, titled 3D Bioprinting of Living Tissues & Organs.”

3D bioprinting is the process of creating cell patterns in a confined space using 3D-printing technologies, where cell function and viability are preserved within the printed construct.

Recent progress has allowed 3D printing of biocompatible materials, cells and supporting components into complex 3D functional living tissues. The technology is being applied to regenerative medicine to address the need for tissues and organs suitable for transplantation. Compared with non-biological printing, 3D bioprinting involves additional complexities, such as the choice of materials, cell types, growth and differentiation factors, and technical challenges related to the sensitivities of living cells and the construction of tissues. Addressing these complexities requires the integration of technologies from the fields of engineering, biomaterials science, cell biology, physics and medicine, according to nature.com.

“If we’re able to make organs on demand, that will be highly beneficial to society,” said Ozbolat. “We have the capability to pattern cells, locate them and then make the same thing that exists in the body.”

3D bioprinting of tissues and organs

Sean V Murphy & Anthony Atala
Nature Biotechnology 32,773–785(2014)       doi:10.1038/nbt.2958

 

Additive manufacturing, otherwise known as three-dimensional (3D) printing, is driving major innovations in many areas, such as engineering, manufacturing, art, education and medicine. Recent advances have enabled 3D printing of biocompatible materials, cells and supporting components into complex 3D functional living tissues. 3D bioprinting is being applied to regenerative medicine to address the need for tissues and organs suitable for transplantation. Compared with non-biological printing, 3D bioprinting involves additional complexities, such as the choice of materials, cell types, growth and differentiation factors, and technical challenges related to the sensitivities of living cells and the construction of tissues. Addressing these complexities requires the integration of technologies from the fields of engineering, biomaterials science, cell biology, physics and medicine. 3D bioprinting has already been used for the generation and transplantation of several tissues, including multilayered skin, bone, vascular grafts, tracheal splints, heart tissue and cartilaginous structures. Other applications include developing high-throughput 3D-bioprinted tissue models for research, drug discovery and toxicology.

 

Future Technologies : Bioprinting
Bioprinting

3D printing is increasingly permitting the direct digital manufacture (DDM) of a wide variety of plastic and metal items. While this in itself may trigger a manufacturing revolution, far more startling is the recent development of bioprinters. These artificially construct living tissue by outputting layer-upon-layer of living cells. Currently all bioprinters are experimental. However, in the future, bioprinters could revolutionize medical practice as yet another element of the New Industrial Convergence.

Bioprinters may be constructed in various configurations. However, all bioprinters output cells from a bioprint head that moves left and right, back and forth, and up and down, in order to place the cells exactly where required. Over a period of several hours, this permits an organic object to be built up in a great many very thin layers.

In addition to outputting cells, most bioprinters also output a dissolvable gel to support and protect cells during printing. A possible design for a future bioprinter appears below and in the sidebar, here shown in the final stages of printing out a replacement human heart. Note that you can access larger bioprinter images on the Future Visions page. You may also like to watch my bioprinting video.

bioprinter

 

Bioprinting Pioneers

Several experimental bioprinters have already been built. For example, in 2002 Professor Makoto Nakamura realized that the droplets of ink in a standard inkjet printer are about the same size as human cells. He therefore decided to adapt the technology, and by 2008 had created a working bioprinter that can print out biotubing similar to a blood vessel. In time, Professor Nakamura hopes to be able to print entire replacement human organs ready for transplant. You can learn more about this groundbreaking work here or read this message from Professor Nakamura. The movie below shows in real-time the biofabrication of a section of biotubing using his modified inkjet technology.

 

Another bioprinting pioneer is Organovo. This company was set up by a research group lead by Professor Gabor Forgacs from the University of Missouri, and in March 2008 managed to bioprint functional blood vessels and cardiac tissue using cells obtained from a chicken. Their work relied on a prototype bioprinter with three print heads. The first two of these output cardiac and endothelial cells, while the third dispensed a collagen scaffold — now termed ‘bio-paper’ — to support the cells during printing.

Since 2008, Organovo has worked with a company called Invetech to create a commercial bioprinter called the NovoGen MMX. This is loaded with bioink spheroids that each contain an aggregate of tens of thousands of cells. To create its output, the NovoGen first lays down a single layer of a water-based bio-paper made from collagen, gelatin or other hydrogels. Bioink spheroids are then injected into this water-based material. As illustrated below, more layers are subsequently added to build up the final object. Amazingly, Nature then takes over and the bioink spheroids slowly fuse together. As this occurs, the biopaper dissolves away or is otherwise removed, thereby leaving a final bioprinted body part or tissue.

 

bioprinting stages

As Organovo have demonstrated, using their bioink printing process it is not necessary to print all of the details of an organ with a bioprinter, as once the relevant cells are placed in roughly the right place Nature completes the job. This point is powerfully illustrated by the fact that the cells contained in a bioink spheroid are capable of rearranging themselves after printing. For example, experimental blood vessels have been bioprinted using bioink spheroids comprised of an aggregate mix of endothelial, smooth muscle and fibroblast cells. Once placed in position by the bioprint head, and with no technological intervention, the endothelial cells migrate to the inside of the bioprinted blood vessel, the smooth muscle cells move to the middle, and the fibroblasts migrate to the outside.

In more complex bioprinted materials, intricate capillaries and other internal structures also naturally form after printing has taken place. The process may sound almost magical. However, as Professor Forgacs explains, it is no different to the cells in an embryo knowing how to configure into complicated organs. Nature has been evolving this amazing capability for millions of years. Once in the right places, appropriate cell types somehow just know what to do.

In December 2010, Organovo create the first blood vessels to be bioprinted using cells cultured from a single person. The company has also successfully implanted bioprinted nerve grafts into rats, and anticipates human trials of bioprinted tissues by 2015. However, it also expects that the first commercial application of its bioprinters will be to produce simple human tissue structures for toxicology tests. These will enable medical researchers to test drugs on bioprinted models of the liver and other organs, thereby reducing the need for animal tests.

In time, and once human trials are complete, Organovo hopes that its bioprinters will be used to produce blood vessel grafts for use in heart bypass surgery. The intention is then to develop a wider range of tissue-on-demand and organs-on-demand technologies. To this end, researchers are now working on tiny mechanical devices that can artificially exercise and hence strengthen bioprinted muscle tissue before it is implanted into a patient.

Organovo anticipates that its first artificial human organ will be a kidney. This is because, in functional terms, kidneys are one of the more straight-forward parts of the body. The first bioprinted kidney may in fact not even need to look just like its natural counterpart or duplicate all of its features. Rather, it will simply have to be capable of cleaning waste products from the blood. You can read more about the work of Organovoand Professor Forgac’s in this article from Nature.

Regenerative Scaffolds and Bones

A further research team with the long-term goal of producing human organs-on-demand has created the Envisiontec Bioplotter. Like Organovo’s NovoGen MMX, this outputs bio-ink ’tissue spheroids’ and supportive scaffold materials including fibrin and collagen hydrogels. But in addition, the Envisontech can also print a wider range of biomaterials. These include biodegradable polymers and ceramics that may be used to support and help form artificial organs, and which may even be used as bioprinting substitutes for bone.

Talking of bone, a team lead by Jeremy Mao at the Tissue Engineering and Regenerative Medicine Lab at Columbia University is working on the application of bioprinting in dental and bone repairs. Already, a bioprinted, mesh-like 3D scaffold in the shape of an incisor has been implanted into the jaw bone of a rat. This featured tiny, interconnecting microchannels that contained ‘stem cell-recruiting substances’. In just nine weeks after implantation, these triggered the growth of fresh periodontal ligaments and newly formed alveolar bone. In time, this research may enable people to be fitted with living, bioprinted teeth, or else scaffolds that will cause the body to grow new teeth all by itself. You can read more about this development in this article from The Engineer.

In another experient, Mao’s team implanted bioprinted scaffolds in the place of the hip bones of several rabbits. Again these were infused with growth factors. As reported inThe Lancet, over a four month period the rabbits all grew new and fully-functional joints around the mesh. Some even began to walk and otherwise place weight on their new joints only a few weeks after surgery. Sometime next decade, human patients may therefore be fitted with bioprinted scaffolds that will trigger the grown of replacement hip and other bones. In a similar development, a team from Washington State University have also recently reported on four years of work using 3D printers to create a bone-like material that may in the future be used to repair injuries to human bones.

In Situ Bioprinting

The aforementioned research progress will in time permit organs to be bioprinted in a lab from a culture of a patient’s own cells. Such developments could therefore spark a medical revolution. Nevertheless, others are already trying to go further by developing techniques that will enable cells to be printed directly onto or into the human body in situ. Sometime next decade, doctors may therefore be able to scan wounds and spray on layers of cells to very rapidly heal them.

Already a team of bioprinting researchers lead by Anthony Alata at the Wake Forrest School of Medicine have developed a skin printer. In initial experiments they have taken 3D scans of test injuries inflicted on some mice and have used the data to control a bioprint head that has sprayed skin cells, a coagulant and collagen onto the wounds. The results are also very promising, with the wounds healing in just two or three weeks compared to about five or six weeks in a control group. Funding for the skin-printing project is coming in part from the US military who are keen to develop in situ bioprinting to help heal wounds on the battlefield. At present the work is still in a pre-clinical phase with Alata progressing his research usig pigs. However, trials of with human burn victims could be a little as five years away.

The potential to use bioprinters to repair our bodies in situ is pretty mind blowing. In perhaps no more than a few decades it may be possible for robotic surgical arms tipped with bioprint heads to enter the body, repair damage at the cellular level, and then also repair their point of entry on their way out. Patients would still need to rest and recuperate for a few days as bioprinted materials fully fused into mature living tissue. However, most patients could potentially recover from very major surgery in less than a week.

Cosmetic Applications …

Bioprinting Implications …

More information on bioprinting can be found in my books 3D Printing: Second Editionand The Next Big Thing. There is also a bioprinting section in my 3D Printing Directory. Oh, and there is also a great infographic about bioprinting here. Enjoy!

 

How to print out a blood vessel

New work moves closer to the age of organs on demand.

Blood vessels can now be ‘printed out’ by machine. Could bigger structures be in the future?SUSUMU NISHINAGA / SCIENCE PHOTO LIBRARY

Read Full Post »


Problem of Science Doctorate Programs

Larry H. Bernstein, MD, FCAP, Curator

LPBI

 

 

The Problem in Biomedical Education

Henry Bourne (UCSF)

Dr. Henry Bourne has trained graduate students and postdocs at UCSF for over 40 years. In his iBiology talk, he discusses the imminent need for change in graduate education. With time to degrees getting longer, the biomedical community needs to create experimental graduate programs to find more effective and low cost ways to train future scientists and run successful laboratories. If we don’t start looking for solutions, the future of the biomedical enterprise will grow increasingly unstable.

Watch Henry Bourne’s iBioMagazine: The Problem in Biomedical Education

https://youtu.be/V9peRqNr-L0

Henry Bourne is Professor Emeritus and former chair of the Department of Pharmacology at the University of California – San Francisco. His research focused on trimeric G-proteins, G-protein coupled receptors, and the cellular signals responsible for polarity and direction-finding of human leukocytes. He is the author of several books including a memoir, Ambition and Delight, and has written extensively about graduate training and biomedical workforce issues. Now Dr. Bourne’s research focuses on the organization and founding of US biomedical research in the early 20th century.

Related Talks

Read Full Post »


Conduction, graphene, elements and light

Larry H. Bernstein, MD, FCAP, Curator

LPBI

 

New 2D material could upstage graphene   Mar 25, 2016

Can function as a conductor or semiconductor, is extremely stable, and uses light, inexpensive earth-abundant elements
http://www.kurzweilai.net/new-2d-material-could-upstage-graphene
The atoms in the new structure are arranged in a hexagonal pattern as in graphene, but that is where the similarity ends. The three elements forming the new material all have different sizes; the bonds connecting the atoms are also different. As a result, the sides of the hexagons formed by these atoms are unequal, unlike in graphene. (credit: Madhu Menon)

A new one-atom-thick flat material made up of silicon, boron, and nitrogen can function as a conductor or semiconductor (unlike graphene) and could upstage graphene and advance digital technology, say scientists at the University of Kentucky, Daimler in Germany, and the Institute for Electronic Structure and Laser (IESL) in Greece.

Reported in Physical Review B, Rapid Communications, the new Si2BN material was discovered in theory (not yet made in the lab). It uses light, inexpensive earth-abundant elements and is extremely stable, a property many other graphene alternatives lack, says University of Kentucky Center for Computational Sciences physicist Madhu Menon, PhD.

Limitations of other 2D semiconducting materials

A search for new 2D semiconducting materials has led researchers to a new class of three-layer materials called transition-metal dichalcogenides (TMDCs). TMDCs are mostly semiconductors and can be made into digital processors with greater efficiency than anything possible with silicon. However, these are much bulkier than graphene and made of materials that are not necessarily earth-abundant and inexpensive.

Other graphene-like materials have been proposed but lack the strengths of the new material. Silicene, for example, does not have a flat surface and eventually forms a 3D surface. Other materials are highly unstable, some only for a few hours at most.

The new Si2BN material is metallic, but by attaching other elements on top of the silicon atoms, its band gap can be changed (from conductor to semiconductor, for example) — a key advantage over graphene for electronics applications and solar-energy conversion.

The presence of silicon also suggests possible seamless integration with current silicon-based technology, allowing the industry to slowly move away from silicon, rather than precipitously, notes Menon.

https://youtu.be/lKc_PbTD5go

Abstract of Prediction of a new graphenelike Si2BN solid

While the possibility to create a single-atom-thick two-dimensional layer from any material remains, only a few such structures have been obtained other than graphene and a monolayer of boron nitride. Here, based upon ab initiotheoretical simulations, we propose a new stable graphenelike single-atomic-layer Si2BN structure that has all of its atoms with sp2 bonding with no out-of-plane buckling. The structure is found to be metallic with a finite density of states at the Fermi level. This structure can be rolled into nanotubes in a manner similar to graphene. Combining first- and second-row elements in the Periodic Table to form a one-atom-thick material that is also flat opens up the possibility for studying new physics beyond graphene. The presence of Si will make the surface more reactive and therefore a promising candidate for hydrogen storage.

 

Nano-enhanced textiles clean themselves with light

Catalytic uses for industrial-scale chemical processes in agrochemicals, pharmaceuticals, and natural products also seen
http://www.kurzweilai.net/nano-enhanced-textiles-clean-themselves-with-light
Close-up of nanostructures grown on cotton textiles. Image magnified 150,000 times. (credit: RMIT University)

Researchers at at RMIT University in Australia have developed a cheap, efficient way to grow special copper- and silver-based nanostructures on textiles that can degrade organic matter when exposed to light.

Don’t throw out your washing machine yet, but the work paves the way toward nano-enhanced textiles that can spontaneously clean themselves of stains and grime simply by being put under a light or worn out in the sun.

The nanostructures absorb visible light (via localized surface plasmon resonance — collective electron-charge oscillations in metallic nanoparticles that are excited by light), generating high-energy (“hot”) electrons that cause the nanostructures to act as catalysts for chemical reactions that degrade organic matter.

Steps involved in fabricating copper- and silver-based cotton fabrics: 1. Sensitize the fabric with tin. 2. Form palladium seeds that act as nucleation (clustering) sites. 3. Grow metallic copper and silver nanoparticles on the surface of the cotton fabric. (credit: Samuel R. Anderson et al./Advanced Materials Interfaces)

The challenge for researchers has been to bring the concept out of the lab by working out how to build these nanostructures on an industrial scale and permanently attach them to textiles. The RMIT team’s novel approach was to grow the nanostructures directly onto the textiles by dipping them into specific solutions, resulting in development of stable nanostructures within 30 minutes.

When exposed to light, it took less than six minutes for some of the nano-enhanced textiles to spontaneously clean themselves.

The research was described in the journal Advanced Materials Interfaces.

Scaling up to industrial levels

Rajesh Ramanathan, a RMIT postdoctoral fellow and co-senior author, said the process also had a variety of applications for catalysis-based industries such as agrochemicals, pharmaceuticals, and natural productsand could be easily scaled up to industrial levels. “The advantage of textiles is they already have a 3D structure, so they are great at absorbing light, which in turn speeds up the process of degrading organic matter,” he said.

Cotton textile fabric with copper-based nanostructures. The image is magnified 200 times. (credit: RMIT University)

“Our next step will be to test our nano-enhanced textiles with organic compounds that could be more relevant to consumers, to see how quickly they can handle common stains like tomato sauce or wine,” Ramanathan said.

“There’s more work to do to before we can start throwing out our washing machines, but this advance lays a strong foundation for the future development of fully self-cleaning textiles.”


Abstract of Robust Nanostructured Silver and Copper Fabrics with Localized Surface Plasmon Resonance Property for Effective Visible Light Induced Reductive Catalysis

Inspired by high porosity, absorbency, wettability, and hierarchical ordering on the micrometer and nanometer scale of cotton fabrics, a facile strategy is developed to coat visible light active metal nanostructures of copper and silver on cotton fabric substrates. The fabrication of nanostructured Ag and Cu onto interwoven threads of a cotton fabric by electroless deposition creates metal nanostructures that show a localized surface plasmon resonance (LSPR) effect. The micro/nanoscale hierarchical ordering of the cotton fabrics allows access to catalytically active sites to participate in heterogeneous catalysis with high efficiency. The ability of metals to absorb visible light through LSPR further enhances the catalytic reaction rates under photoexcitation conditions. Understanding the modes of electron transfer during visible light illumination in Ag@Cotton and Cu@Cotton through electrochemical measurements provides mechanistic evidence on the influence of light in promoting electron transfer during heterogeneous catalysis for the first time. The outcomes presented in this work will be helpful in designing new multifunctional fabrics with the ability to absorb visible light and thereby enhance light-activated catalytic processes.

 

New type of molecular tag makes MRI 10,000 times more sensitive

Could detect biochemical processes in opaque tissue without requiring PET radiation or CT x-rays
http://www.kurzweilai.net/new-type-of-molecular-tag-makes-mri-10000-times-more-sensitive

Duke scientists have discovered a new class of inexpensive, long-lived molecular tags that enhance MRI signals by 10,000 times. To activate the tags, the researchers mix them with a newly developed catalyst (center) and a special form of hydrogen (gray), converting them into long-lived magnetic resonance “lightbulbs” that might be used to track disease metabolism in real time. (credit: Thomas Theis, Duke University)

Duke University researchers have discovered a new form of MRI that’s 10,000 times more sensitive and could record actual biochemical reactions, such as those involved in cancer and heart disease, and in real time.

Let’s review how MRI (magnetic resonance imaging) works: MRI takes advantage of a property called spin, which makes the nuclei in hydrogen atoms act like tiny magnets. By generating a strong magnetic field (such as 3 Tesla) and a series of radio-frequency waves, MRI induces these hydrogen magnets in atoms to broadcast their locations. Since most of the hydrogen atoms in the body are bound up in water, the technique is used in clinical settings to create detailed images of soft tissues like organs (such as the brain), blood vessels, and tumors inside the body.


MRI’s ability to track chemical transformations in the body has been limited by the low sensitivity of the technique. That makes it impossible to detect small numbers of molecules (without using unattainably more massive magnetic fields).

So to take MRI a giant step further in sensitivity, the Duke researchers created a new class of molecular “tags” that can track disease metabolism in real time, and can last for more than an hour, using a technique called hyperpolarization.* These tags are biocompatible and inexpensive to produce, allowing for using existing MRI machines.

“This represents a completely new class of molecules that doesn’t look anything at all like what people thought could be made into MRI tags,” said Warren S. Warren, James B. Duke Professor and Chair of Physics at Duke, and senior author on the study. “We envision it could provide a whole new way to use MRI to learn about the biochemistry of disease.”

Sensitive tissue detection without radiation

The new molecular tags open up a new world for medicine and research by making it possible to detect what’s happening in optically opaque tissue instead of requiring expensive positron emission tomography (PET), which uses a radioactive tracer chemical to look at organs in the body and only works for (typically) about 20 minutes, or CT x-rays, according to the researchers.

This research was reported in the March 25 issue of Science Advances. It was supported by the National Science Foundation, the National Institutes of Health, the Department of Defense Congressionally Directed Medical Research Programs Breast Cancer grant, the Pratt School of Engineering Research Innovation Seed Fund, the Burroughs Wellcome Fellowship, and the Donors of the American Chemical Society Petroleum Research Fund.

* For the past decade, researchers have been developing methods to “hyperpolarize” biologically important molecules. “Hyperpolarization gives them 10,000 times more signal than they would normally have if they had just been magnetized in an ordinary magnetic field,” Warren said. But while promising, Warren says these hyperpolarization techniques face two fundamental problems: incredibly expensive equipment — around 3 million dollars for one machine — and most of these molecular “lightbulbs” burn out in a matter of seconds.

“It’s hard to take an image with an agent that is only visible for seconds, and there are a lot of biological processes you could never hope to see,” said Warren. “We wanted to try to figure out what molecules could give extremely long-lived signals so that you could look at slower processes.”

So the researchers synthesized a series of molecules containing diazarines — a chemical structure composed of two nitrogen atoms bound together in a ring. Diazirines were a promising target for screening because their geometry traps hyperpolarization in a “hidden state” where it cannot relax quickly. Using a simple and inexpensive approach to hyperpolarization called SABRE-SHEATH, in which the molecular tags are mixed with a spin-polarized form of hydrogen and a catalyst, the researchers were able to rapidly hyperpolarize one of the diazirine-containing molecules, greatly enhancing its magnetic resonance signals for over an hour.

The scientists believe their SABRE-SHEATH catalyst could be used to hyperpolarize a wide variety of chemical structures at a fraction of the cost of other methods.


Abstract of Direct and cost-efficient hyperpolarization of long-lived nuclear spin states on universal 15N2-diazirine molecular tags

Abstract of Direct and cost-efficient hyperpolarization of long-lived nuclear spin states on universal 15N2-diazirine molecular tags

Conventional magnetic resonance (MR) faces serious sensitivity limitations, which can be overcome by hyperpolarization methods, but the most common method (dynamic nuclear polarization) is complex and expensive, and applications are limited by short spin lifetimes (typically seconds) of biologically relevant molecules. We use a recently developed method, SABRE-SHEATH, to directly hyperpolarize 15N2 magnetization and long-lived 15N2singlet spin order, with signal decay time constants of 5.8 and 23 min, respectively. We find >10,000-fold enhancements generating detectable nuclear MR signals that last for more than an hour. 15N2-diazirines represent a class of particularly promising and versatile molecular tags, and can be incorporated into a wide range of biomolecules without significantly altering molecular function.

references:

[Seems like they have a great idea, now all they need to do is confirm very specific uses or types of cancers/diseases or other processes they can track or target. Will be interesting to see if they can do more than just see things, maybe they can use this to target and destroy bad things in the body also. Keep up the good work….. this sounds like a game changer.]

 

Scientists time-reverse developed stem cells to make them ‘embryonic’ again

May help avoid ethically controversial use of human embryos for research and support other research goals
http://www.kurzweilai.net/scientists-time-reverse-developed-stem-cells-to-make-them-embryonic-again
Researchers have reversed “primed” (developed) “epiblast” stem cells (top) from early mouse embryos using the drug MM-401, causing the treated cells (bottom) to revert to the original form of the stem cells. (credit: University of Michigan)

University of Michigan Medical School researchers have discovered a way to convert mouse stem cells (taken from an embryo) that have  become “primed” (reached the stage where they can  differentiate, or develop into every specialized cell in the body) to a “naïve” (unspecialized) state by simply adding a drug.

This breakthrough has the potential to one day allow researchers to avoid the ethically controversial use of human embryos left over from infertility treatments. To achieve this breakthrough, the researchers treated the primedembryonic stem cells (“EpiSC”) with a drug called MM-401* (a leukemia drug) for a short period of time.

Embryonic stem cells are able to develop into any type of cell, except those of the placenta (credit: Mike Jones/CC)

…..

* The drug, MM-401, specifically targets epigenetic chemical markers on histones, the protein “spools” that DNA coils around to create structures called chromatin. These epigenetic changes signal the cell’s DNA-reading machinery and tell it where to start uncoiling the chromatin in order to read it.

A gene called Mll1 is responsible for the addition of these epigenetic changes, which are like small chemical tags called methyl groups. Mll1 plays a key role in the uncontrolled explosion of white blood cells in leukemia, which is why researchers developed the drug MM-401 to interfere with this process. But Mll1 also plays a role in cell development and the formation of blood cells and other cells in later-stage embryos.

Stem cells do not turn on the Mll1 gene until they are more developed. The MM-401 drug blocks Mll1’s normal activity in developing cells so the epigenetic chemical markers are missing. These cells are then unable to continue to develop into different types of specialized cells but are still able to revert to healthy naive pluripotent stem cells.


Abstract of MLL1 Inhibition Reprograms Epiblast Stem Cells to Naive Pluripotency

The interconversion between naive and primed pluripotent states is accompanied by drastic epigenetic rearrangements. However, it is unclear whether intrinsic epigenetic events can drive reprogramming to naive pluripotency or if distinct chromatin states are instead simply a reflection of discrete pluripotent states. Here, we show that blocking histone H3K4 methyltransferase MLL1 activity with the small-molecule inhibitor MM-401 reprograms mouse epiblast stem cells (EpiSCs) to naive pluripotency. This reversion is highly efficient and synchronized, with more than 50% of treated EpiSCs exhibiting features of naive embryonic stem cells (ESCs) within 3 days. Reverted ESCs reactivate the silenced X chromosome and contribute to embryos following blastocyst injection, generating germline-competent chimeras. Importantly, blocking MLL1 leads to global redistribution of H3K4me1 at enhancers and represses lineage determinant factors and EpiSC markers, which indirectly regulate ESC transcription circuitry. These findings show that discrete perturbation of H3K4 methylation is sufficient to drive reprogramming to naive pluripotency.


Abstract of Naive Pluripotent Stem Cells Derived Directly from Isolated Cells of the Human Inner Cell Mass

Conventional generation of stem cells from human blastocysts produces a developmentally advanced, or primed, stage of pluripotency. In vitro resetting to a more naive phenotype has been reported. However, whether the reset culture conditions of selective kinase inhibition can enable capture of naive epiblast cells directly from the embryo has not been determined. Here, we show that in these specific conditions individual inner cell mass cells grow into colonies that may then be expanded over multiple passages while retaining a diploid karyotype and naive properties. The cells express hallmark naive pluripotency factors and additionally display features of mitochondrial respiration, global gene expression, and genome-wide hypomethylation distinct from primed cells. They transition through primed pluripotency into somatic lineage differentiation. Collectively these attributes suggest classification as human naive embryonic stem cells. Human counterparts of canonical mouse embryonic stem cells would argue for conservation in the phased progression of pluripotency in mammals.

 

 

How to kill bacteria in seconds using gold nanoparticles and light

March 24, 2016

 

zapping bacteria ft Could treat bacterial infections without using antibiotics, which could help reduce the risk of spreading antibiotics resistance

Researchers at the University of Houston have developed a new technique for killing bacteria in 5 to 25 seconds using highly porous gold nanodisks and light, according to a study published today in Optical Materials Express. The method could one day help hospitals treat some common infections without using antibiotics

Read Full Post »


Organic MolecuLED versus Inorganic Quantum Dots and Medical Applications

Curator: Danut Dragoi, PhD

Quantum Dots are good fluorescent markers for biological and biomedical applications, in particular in cellular imaging, see link in here . Moreover, they have attracted great interest for their potential application in electronic and optoelectronic devices see link in here. Strongly luminescent semiconductor nanocrystals are highly desirable for a large number of optoelectronic applications, such as light-emitting diodes (LEDs), see link in here.

A comparison of Inorganic and Organic Quantum Dot technologies is shown in here.

Quantum dots and related approaches for tailoring and improving the quality of light for specific applications provide a remarkable interest for the buck, which is why they are rapidly penetrating the display and lighting markets. QDs that can go into lighting feature built-in protective layers, so no external environmental seal is required. The material is handled in air like phosphors, and the material has ‘phosphor-like stability’. It is tailored for the heat and luminous flux of on-chip environments. According with Juanita Kurtin, founder and CTO of Pacific Light Technologies (PLT); a venture-funded company established in Portland in 2011 the new organic QD has the absorbance spectrum of PLT’s materials , that barely overlaps with QD emission spectra. This very low self-absorption “enable the high concentration required for on-chip applications and color combinations.” Also, the dot-on-chip approach provides a drop-in replacement for any white LED. It works for all sizes of display, and is the “only QD solution for lighting”, see link in here.

PLT’s dots are cadmium-based, as you would expect for an on-chip approach, but the company is investigating cadmium-free materials, see link in here .

PLT’s senior team comes from just the places you would like them to come from for this sort of development program, and it is intriguing that a start-up may be moving ahead faster on the on-chip materials problem than better-known companies that have been in the business longer. Still, it was not clear from the presentation, see link in here exactly what PLT has done to make their materials more stable.

In Display Daily, it is discussed StoreDot’s organic-film alternative to semiconductor quantum dots, see link in here, and in here. (StoreDot: An Organic Quantum Dot Alternative). Nanosys, see link in here, uses Inorganic (CdSe) NDs have the narrowest full of half maximum peaks at 29 nm width and highest lifetime of 50 k hours. Here we notice the crystallinity effect on QNDs lifetime, since organic materials have less crystalline perfection. However, the Cd and Se elements are a disadvantage in QNDs being toxic and not fully applicable in medicine.

In Table 1 it is shown that StoreDot is the only company using organic-film for making MolecuLED, a great alternative of OLED (organic LED) made at nanoscale using a technique that is kept confidential. However, assembling molecules in a similar way to the atoms arranged in a crystal suggests using the self-assembling molecules techniques. The information in the StoreDot’s website does not mention the excitation type of OQDs (Organic Quantum Dots), electrical in which the organic emitting diodes are controlled, or optical. For this reason MolecuLED(TM) organic technology by @StoreDot is making the Inorganic QDs such as Cadmium / Indium Quantum Dot industry very nervous, see link in here.

Picture below, taken from here, shows rich colors in MolecuLEDTM-embedded device (central frame) compared to standard device (LCD-liquid crystal display) (outer frame).

An excellent site on displays solutions can be reviewed in here.

 

MolecuLED-embeded

Image SOURCE: http://www.store-dot.com/#!technology/c5ue

Table 1

Table 1 MolecuLED

Table 1 SOURCE: http://www.displaydaily.com/display-daily/35647-more-on-quantum-dots-and-qd-replacements-2

 

NB-It is possible that MolecuLED technology can replace the Inorganic QDs in a very short period of time. Besides LCD display applications, the MolecuLEDTM has a great potential in medicine replacing the photo-diode arrays in bio-analytical systems with much denser organic-photodiode-arrays that automatically increase the resolution and the performance of the measuring instrument.

SOURCES

Display solutions: http://www.displaydaily.com/display-daily/35647-more-on-quantum-dots-and-qd-replacements-2

Nanosystem Inc, Inorganic QDhttp://www.nanosysinc.com/what-we-do/quantum-dots/

http://www.hindawi.com/journals/jnm/2014/397469/

http://www.pacificlighttech.com/quantum-dots-in-ssl/

StoreDot, Organic QD: https://www.linkedin.com/pulse/moleculedtm-organic-technology-storedot-making-indium-doron-myersdorf?trk=v-feed

Read Full Post »


The Music of the Elements

Larry H. Bernstein, MD, FCAP, Curator

LPBI

 

A Scientist is Creating Music from the Periodic Table

Mon, 02/29/2016 –   Suzanne Tracy, Editor-in-Chief, Scientific Computing and HPC Source
When researchers ran computer simulations to study vibrations, they noticed that some of the polymers didn’t behave as expected. If they tweaked the starting parameters, the system evolved normally up to a point, but then it diverged into a patterned series of vibrations that were not random. The simulated polymer becomes thermally superconductive — that is, capable of transporting heat with no resistance, much like the existing class of superconducting materials that conduct electricity without resistance.
When researchers ran computer simulations to study vibrations, they noticed that some of the polymers didn’t behave as expected. If they tweaked the starting parameters, the system evolved normally up to a point, but then it diverged into a patterned series of vibrations that were not random. The simulated polymer becomes thermally superconductive — that is, capable of transporting heat with no resistance, much like the existing class of superconducting materials that conduct electricity without resistance.

A researcher at Georgia Institute of Technology has applied for a National Science Foundation grant to create an educational app that would catalog a unique musical signature for each element in the periodic table so that scientists would have a new tool to use in identifying the differences between the molecular structures of solids, liquids and gases. Asegun Henry, Director of the Atomistic Simulation & Energy (ASE) Research Group, and an Assistant Professor in the George W. Woodruff School of Mechanical Engineering, is also in the process of setting all of the elements in the table to music.

“My hope is that it will be an interesting tool to teach the periodic table, but also to give people some notion about the idea that the entire universe is moving around and making noise,” Henry told Gizmodo. “You just can’t hear it.”

As Gizmodo’s Jennifer Ouellette explains, it’s more than just a fun exercise. “Henry and his graduate student, Wei Lv, were interested in a peculiar feature of polymers, long chains of molecules all strung together, with thousands upon thousands of different modes of vibration that interact with each other. Polymers are much more complicated than the simple toy models, so it’s harder to describe their interactions mathematically. Scientists must rely on computer simulations to study the vibrations.”

“How the energy of the interaction changes with respect to the distance between the molecules dictates a lot of the physics,” says Henry. “We have to slow down the vibrations of the atoms so you can hear them, because they’re too fast, and at too high frequencies. But you’ll be able to hear the difference between something low on the periodic table and something like carbon that’s very high. One will sound high-pitched, and one will sound low.”

However, when Henry and Lv ran their computer simulations, they noticed that some of the polymers they were modeling didn’t behave as expected, Ouellette reports. If they tweaked the starting parameters a bit, the system evolved normally up to a point, but then it diverged into a patterned series of vibrations that were not random. The simulated polymer becomes thermally superconductive — that is, capable of transporting heat with no resistance, much like the existing class of superconducting materials that conduct electricity without resistance (albeit at very low temperatures).

“Toy models are fictitious and designed to be really simple and plain so that you can analyze them easily,” said Henry. “We did this with a real system, and the [effect] actually persisted.”

Henry and Lv successfully identified three vibrational modes out of several thousand responsible for the phenomenon. However, traditional analysis techniques — like plotting the amplitudes of the modes over time in a visual graph — didn’t reveal anything significant. It wasn’t until the researchers decided to sonify the data that they pinpointed what was going on. This involved mapping pitch, timbre and amplitude onto the data to translate it into a kind of molecular music. The three modes faded in and out over time and eventually synchronized, creating a kind of sonic feedback loop until the simulated material became thermally superconductive.

“As soon as you play it, your ears pick up on it immediately,” said Henry. So, it’s solid proof-of-principle of sonification as an analytical tool for materials science.

Henry is attempting to identify the underlying mechanism behind the phenomenon in order to understand why it manifests in some polymer systems, but not others. This information could help to actually construct physical thermal superconducting materials. “It would change the world,” said Henry. “Conceptually you’d be able to run a thermal superconducting pipe from the Sahara desert and provide heat to the rest of the world.”

 

Phonon transport at interfaces: Determining the correct modes of vibration

Kiarash Gordiz1 and Asegun Henry1,2,a)

J. Appl. Phys. 119, 015101 (2016); http://dx.doi.org/10.1063/1.4939207

For many decades, phonon transport at interfaces has been interpreted in terms of phonons impinging on an interface and subsequently transmitting a certain fraction of their energy into the other material. It has also been largely assumed that when one joins two bulk materials,interfacialphonon transport can be described in terms of the modes that exist in each material separately. However, a new formalism for calculating the modal contributions to thermal interface conductance with full inclusion of anharmonicity has been recently developed, which now offers a means for checking the validity of this assumption. Here, we examine the assumption of using the bulk materials’ modes to describe the interfacial transport. The results indicate that when two materials are joined, a new set of vibrational modes are required to correctly describe the transport. As the modes are analyzed, certain classifications emerge and some of the most important modes are localized at the interface and can exhibit large conductance contributions that cannot be explained by the current physical picture based on transmission probability.

Article outline:
I. INTRODUCTION

II. ICMA FORMALISM

III. MODAL BASIS SETS

  A. EMD simulations

  B. Wave-packet simulations

IV. CLASSIFICATION OF THE MODES OF VIBRATION

V. CORRELATION MAPPING

VI. CONCLUSION

 

Read Full Post »

Older Posts »