Many processes in organisms based on the self-organization of biological components. For materials scientists, such substances are a dream: you react autonomously to their environment and can adapt to this different conditions. At the U.S. MIT researchers aim to produce such wonders molecules artificially.
self healing materials
Nature does it with impressive elegance: proteins form long fibers, DNA molecules made for rope ladder, fats surround all the cells.These are simply the properties of the involved components that allow them to grow into complex structures.Due to the weak interactions of their atoms their cohesion is flexible – in physics you count those molecules to “soft matter”.This consists of substances that physically can not be sorted properly as a solid or liquid and change their properties with sometimes astonishing speed.
Especially vividly shows the case of maize starch is mixed with water: If you let it slide slowly through your fingers, the mixture is liquid. If you press the hand while she is determined abruptly. You can shape it into a ball that melts away immediately when no force acts on it. Compared with other soft materials of nature, follow these starch molecules but rather simple mechanisms, the physicist says Alfredo Alexander-Katz , who studies the properties of soft materials at the Massachusetts Institute of Technology.
Miracle molecules from the blood
“In the course of evolution, nature had plenty of time to develop soft materials These include the main building blocks of life, such as DNA or proteins are very complex polymers, but offer clever solutions for many problems -.. Considering their mechanisms understand, we can draw from ideas for other applications, “said Alexander-Katz.One of the molecules with which the scientist works, can be found in the bloodstream of any mammal, man included.It prevents you bleed to death internally.
For the cells with which the walls of the blood vessels are lined, die off after some time and need to be replaced. It continuously creates small holes from which one bleeds. So you need a mechanism that mends such leaks immediately and can grow new cells. For this repair service a shapeless tangle of long protein chains is responsible – the von Willebrand factor .As long as the blood flow is disturbed, the migrating giant molecule with all the other components of the blood through the vessels.
Sticky by flow forces
Is it true there is a leak, however, results in a surprise: Where the blood flows, the protein unfolds and becomes sticky.The faster flow rate pulls apart the von Willebrand factor as a Tixorolle.This binding sites of the protein are exposed, specifically adhere to the vessel wall and platelets – it thus initiates blood clotting, a plug forms and closes the hole.The force that must be applied for the pulling is perfectly adapted to the bloodstream: In uninjured vessels of von Willebrand factor is rolled and soluble.
This ability will Alexander-Katz use of synthetic materials: “If we had a substance as this mixture of behaves von Willebrand factor and platelets, you could use it for example for oil Quick Flowing parts would stick together and thereby the. increase shear forces. So you could exploit a source of oil more efficiently, because the discharge pressure would be distributed better. ”
Material and drug carriers
Also for new materials proposes to use the molecules Alexander-Katz.From them “functionally graded materials” could be produced, consisting of a single material, but in different places have different properties – for example, the elasticity of rubber and the rigidity of hard plastic.In a 3-D printer could vary when printed any number of times, thereby producing extremely resistant composites it by changing the flow rate.”The best thing about it,” says the scientist, “is that, cracks in the material would heal by itself.”
For Alexander-Katz, the application possibilities of his favorite molecule are thus still far from exhausted.In its natural environment – the bloodstream – could meet a number of medical purposes of Von Willebrand factor.Because the binding sites with which to dock his protein chains of platelets could change almost arbitrarily.For the physicist, it is conceivable that they are reprogrammed to the detection of certain drugs that are used in the treatment of cancer.Because in many tumor types, there are large amounts of von Willebrand factors – the ulcers grow so fast that they overwhelm the formation of new blood vessels and creep many errors in the vessel walls.
Nanoparticles in cell membrane
With customized von Willebrand proteins could therefore deliver cancer drugs directly to tumors – which would be a huge step forward, because the targeted drug delivery is one of the biggest challenges in drug development.Another project of Alexander-Katz has therefore a similar goal: He is working on a material with which you can carry substances directly into a cell.
It involves nanoparticles through cell membranes can walk without being discovered there.Only the surface of these particles ensures that they penetrate unhindered into the double layer of fat molecules.Quite a feat, because cell membranes have evolved over billions of years to barriers that overcomes hardly a larger molecule unnoticed.The nanoparticles lined up against it by itself next to the other membrane components.In its interior they could thereby contribute substances that they release to the cell.
Artificial immune cells?
The problem is that the nanomaterials penetrate into every cell they encounter.Alexander-Katz therefore wants to train to particular cell types, which can then be treated specifically.The ability of this material, permanently embedded in membranes, he wants to use for other purposes in the future, however.As artificial signal generator they could recognize certain molecules approaching from the outside of a cell, and then trigger an appropriate response within the cell.
The bold vision of the scientist: Artificial immune cells whose targets can be programmed as desired, by incorporating the appropriate nanoparticles in their membrane.A project, which will probably take a long time to complete.So far, finds much of his work rather than computer simulation.Alexander-Katz is confident, however, that self-organizing, soft materials will play an important role for medicine in the not too distant future.
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