What Difference Does the Shape of Your Medicine Make?
Have you ever thought about how some things in life are the perfect shape for their function? Wheels being round really helps them keep the car ride smooth. The keystone in an arch keeps ceilings and walkways from falling down around us. But what about at a much, much, much smaller scale? How about on the nano-scale at around a billionth of a meter? Does the shape of a nano-medication affect its function? That is what researcher Paolo Decuzzi, at Methodist Hospital in Houston, Texas, has been working to find out.
Dr. Decuzzi’s research team has been using mathematical modeling to predict what shapes their nano-medications should have to allow them to interact more often with the cells that line blood vessels. Increasing these interactions will increase the rate at which the nanoparticles can find and target diseased vessels—for example, the ones that supply tumors. Dr. Decuzzi and his colleagues compared spheres, rods and disk-shaped particles.
They learned that rods and disks are the best choice for real world experiments. Those shapes have the greatest surface area that can interact with blood vessel cells as they move though them. If you think about a ball rolling on the floor, only a very small amount of its surface is touching the floor at any one time. But with rods or disks, a larger percentage of the surface would touch the floor as they roll along.
From these virtual results, the team decided to make three different size disks and two different size rods to test in the lab. All were small enough to move through blood vessels easily, but with different dimensions. Of the five shapes tested, the middle-sized disk particle was best able to interact with cells in a model of diseased blood vessels under the microscope. This gives the researchers a lead on what the best shape for future medications may be.
What is really interesting about this result is how the disk shape they found to be the best is really similar to the shape of red blood cells. And red blood cells, not surprisingly, also need to interact with the walls of blood vessels to do their job. So maybe we should add the disk shape, at least on the nano scale, to the rank of the wheel and the keystone as one of the best shapes out there to get the job done.
Image: By Alexandre Janoski (http://kacheron.deviantart.com/art/Bloodcells-2-181404756) and licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License.
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