"endthiolated poly(3-(2-ethylhexyl)-thiophene), hereafter referred to as EHPT."
polyethylhexylthiphene EHPT:====================
I believe this is used for knee replacement, pacemaker, nerves in nerve diseases.
seems they are biodegradable, or soluable.
Precursor means is apt to have the telling signs of a disease.
I believe cloning nerves was used to compare inorganic substances to substitute
for the repair of damaged nerves.
===========================
Conductive polymer "molecular wires" increase conductance across artificial cell membranesAbstract
Highly intimate contact between an electrode and a living neuron is strongly desired by both basic neuroscientists and engineers seeking to develop more effective neural prostheses. The net resistance between electrode and cell must be decreased in order to improve the quality of recordings and deliver the minimum necessary stimulating current specifically to the target cell. The ideal situation would be to establish chronic intracellular contact, bypassing the resistance of the cell membrane and the surrounding tissue. We present here evidence that regioregular
polythiophene conductive polymers increase the electrical conductance of an artificial lipid bilayer that simulates a cell membrane. Our initial data on its behavior suggest that the polymer is freely diffusing within the lipid phase. This implies that these polymers, if tethered to a larger microelectrode, could permit long-term sustainable intracellular stimulation and recording. We therefore believe that this new molecule, when further developed, has the potential to significantly improve the performance of existing chronic electrode systems and possibly to enable new types of biosensors.
ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=1404205===================
Artificial cell membranes? =======================
Artificial Cells
NASA-supported researchers are learning to make designer cells for dehydrated blood supplies and space-age medicines.
Building on previous work that was published in the 16 January 2008 issue of Journal of the American Chemical Society, Keating and her colleagues built a model cell using as the cytoplasm a solution of two different polymers: polyethyleneglycol (PEG) and dextran. The researchers encapsulated this polymer solution inside a cell membrane and, because the two polymers do not mix, one of the phases surrounded the other like the white of an egg around a yolk. The team then exposed the cell to a concentrated solution of sugar. Through a process known as osmosis--in which water diffuses across a cell membrane from a region of higher water concentration to a region of lower water concentration--water traveled from the relatively diluted polymer solution inside the cell to the more concentrated sugar solution outside the cell. As a result, the volume of the polymer solution inside the membrane was reduced.
With a cell membrane that was now too large and also unconstrained by its spherical shape, the cell converted to a budded form. A dextran-rich mixture filled the bud while a PEG-rich mixture remained inside the body of the cell. This new structure exhibited the type of complexity that the team had been looking for; it exhibited polarity. "Polarity is critical to development," said Keating. "It is an important first step in the development of a complex multi-cellular organism, like a human being, in which different cells perform different functions."
In previous work, the team created a membrane that was entirely uniform, but in their most recent paper, they describe an asymmetric membrane containing a mixture of lipid molecules. Some of these lipid molecules contained tiny pieces of PEG, which interacted with the PEG in the cytoplasm, thus generating polarity in the model cell. "Our work demonstrated the interrelationship of the cytoplasm and the cell membrane," said Keating.
The team's next step is to create a cascade in polarity. "By creating a model cytoplasm with different compositions, we demonstrated that we can control the behavior of cell membranes," said Keating. "Now we want to find out what will happen if, for example, we add an enzyme whose activity depends on the compositions of the cytoplasm and cell membrane."
Although Keating and her colleagues plan to continue adding components to their model cell, they don't expect to make a real cell. "We aren't trying to generate life here. Rather, we want to understand the physical principles that govern biological systems," said Keating. "For me the big picture is trying to understand how the staggering complexity observed in biological systems might have arisen from seemingly simple chemical and physical principles."
www.sciencedaily.com/releases/2008/05/080515171023.htmNow here they are not making artificial cell for use but for study, however, I was intrigued
by this fact that they were looking for a particular enzyme.
now, this from NASA:
May 29, 2003: Red blood cells are great at carrying oxygen. Unfortunately, that's about all they do. Let's face it: with a little bit of help, they could be a lot more useful.
Right: Red blood cells. Credit: Iowa St. University
Imagine, for example, blood cells that could carry all kinds of things--medication as well as oxygen. Imagine blood that could be dehydrated, and stored for months or even years at a time. It could be carried by medics onto a battlefield--or by astronauts into outer space. Imagine blood that could be used for transfusions with no risk of AIDS or any other disease.
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A group of university researchers is helping NASA develop an artificial cell that can do all this and more.
Bioengineers Dan Hammer and Dennis Discher of the University of Pennsylvania and Frank Bates of the University of Minnesota have created a special kind of molecule--a polymer--that forms something very like a cell membrane, and they've been able to coax these membranes into artificial cells, or polymersomes, that are stronger and more easily manageable than the real thing.
A polymer is simply a chain of smaller molecules that have been linked together. The cellulose in plants and the wool on sheep are natural polymers. Man-made polymers can be found in everything from nylon stockings to car parts to furniture stuffing.
The polymers used in polymersomes are larger and heavier than the natural molecules in cell membranes: They've got a molecular weight of over 3600, compared to about 750 for phospholipids, the fatty acid molecules used by cells.
see captionManmade molecules can be crafted with an important characteristic, which many naturally occurring molecules share; they can be engineered to be amphiphilic, where one end seeks water, and the other end avoids it. In a water-based solution, such molecules spontaneously arrange themselves into a double-layer with their hydrophobic (water fearing) tails in the middle and their hydrophilic (water loving) heads on the outside.
Above: Phospholipid molecules arrange themselves tail-to-tail in a double-layered membrane. [more]
"That was our insight," said Hammer. "We realized that there's nothing that prevents a polymer from forming a bilayer like a phospholipid would."
But polymersomes have one huge advantage: they can be controlled. By adding in different molecules, researchers are learning to manipulate their abilities and make them do things that biological cells just can't manage.
For example, polymersomes can be made strong. While it's true that the phospholipids in natural membranes hold together, they don't bond with each other very tightly. They move around within the cell membrane, and, without the pressure of a watery environment, they fall apart.
see captionLeft: Giant, 2-20 mm, polymersomes in phosphate buffered saline – visualized by phase-contrast microscopy (internal solution of 300 mM sucrose). Credit: University of Pennsylvania
Polymersomes, on the other hand, can be designed so that they cling to each other tightly. Their atoms can bond not only within a single polymer, but also to the polymers next to them. This is called cross-linking, and it vastly increases the strength of artificial cells. (It's cross-linking that stiffens the curls in a beauty-shop permanent enough to keep the shape of the hair-do.) In fact, between cross-linking and the increased molecular weight of the polymers, polymersomes are a thousand-fold stronger than phospholipid cells.
"Probably the main advantage from NASA's point of view," says Hammer, "is that once the polymersomes are crosslinked, the cells become durable enough to be dehydrated into a powder." They can be stored easily, for a long time, and without taking up much space. In other words, it would be a perfect way to carry extra blood for medical emergencies on long distance voyages in outer space.
That, in fact, is the use that he and his colleagues initially envisioned, says Hammer. But they quickly realized that the polymersomes could be used for transporting other things.
Hammer explains: It's easy to encapsulate many kinds of molecules with polymersomes; such artificial cells could then be sent throughout the body. Because their outer membrane consists of molecules that don't interact with cells, polymersomes are invisible to the immune system. They can travel unhampered through the bloodstream.
see captionPolymersomes can also be engineered so that some types of cells do react to them. Hammer, Discher and colleagues can add to their polymersomes particular molecules that latch onto the cells they're targeting. Typically, says Hammer, the polymersomes float through the bloodstream for about 18 hours before they reach their destination and grab onto the target cells.
Right: This sequence of microscopic photos shows how a tough crosslinked polymersome can be dehydrated (for, e.g., easy storage and transportation) and rehydrated again. Credit: University of Pennsylvania
The key word is "target." Doctors using polymersomes wouldn't have to pepper the entire body with medications. They could be targeted--sent only to the places they're needed. Arthritis medications, for example, could be sent only to a patient's swollen fingers, without the risk of causing reactions elsewhere. Polymersomes could carry cancer-zapping pharmaceuticals directly to a tumor. They could incorporate imaging agents like iron oxide particles, which can be detected by magnetic resonance imaging. If these particles are encapsulated into polymersomes designed to latch onto cancer cells, they'd be able to locate small tumor cells that have migrated through the body
Polymersomes could theoretically be designed to carry both the imaging agents that locate a problem, and the medication that treats it.
see captionLeft: Prof. Dan Hammer chairs the University of Pennsylvania's Bioengineering Dept., a leading center of polymersome research. [more]
Using manmade materials to produce an artificial cell is "a highly novel concept," says Hammer. "I think that NASA saw this as a wonderful material, and they wanted to see how far it could evolve." In some conditions, he says, polymersomes take on shapes that are very reminiscent of the ones biological cells take on when, for instance, they're dividing.
And Hammer and his colleagues are still exploring the possibilities. They're experimenting with different types of polymers, to see how the capabilities of artificial cells can be expanded."
science.nasa.gov/headlines/y2003/29may_polymersomes.htm========================
I know above is long article but notice the polymersomes, and
why does the NASA need this so badly?but what is even more intriguing is this:=============================
Polymersomes:
Tough Vesicles Made from Diblock CopolymersVesicles were made from
amphiphilic diblock copolymers and characterized by micromanipulation. The
average molecular weight of the specific polymer studied, polyethyleneoxide-polyethylethylene (EO40-EE37),
is several-fold greater than that of typical phospholipids in natural membranes. Both the membrane bending
and area expansion moduli of electroformed polymersomes (
polymer-based liposomes) fell within the range of
lipid membrane measurements, but the giant polymersomes proved to be almost an order of magnitude
tougher and sustained far greater areal strain before rupture. The polymersome membrane was also at least
tenfold less permeable to water than common phospholipid bilayers.
The results suggest a new class of
synthetic thin-shelled capsules based on block copolymer chemistry.....on pages 13, 14 and 16, those forms look similar to Carnicom's submicron struture, and
the nucleus within the cell.
check out the photos:
they seem to connect one to another and make a chain:=============================
www.uphs.upenn.edu/ime/polymer.pdfskyship