Ann Arbor (MI) – Researchers at National Institute for Standards and Technology (NIST) have discovered a flaw in existing DNA elasticity models. The flaw affects simulation accuracy and it is believed this new finding may even be significant enough to create a new international standard for measuring pico-forces.
Everyone is taught early on that DNA is the basic building block of life, a type of blueprint for how everything comes together. But DNA also has a much less published trait in that it is a very “stretchy polymer.” In fact, it’s so specifically stretchy that scientists believe its measurement could serve as the foundation for a new international standard in measuring extremely small forces, below 1 pN (pico-Newton). To put this pN range force scale into perspective, consider that 1 milliwatt of light (about the amount emitted from common hand-held red laser pointers) reflecting off a mirror generates about 6 pN of force. The DNA polymer would set the standard somewhere around 0.1 pN. I suggest they call it the deyton (prounced day-ton), meaning the reflected force off the mirror would be 60 deytons.
DNA elasticity today has been measured using laser light. In part of the DNA chain, one section is anchored while an infrared laser strikes another molecule. A second laser is then used to measure the distance it moves. By varying the force of the infrared laser the molecule can be pushed and prodded, much like a tree branch. When pushed with a certain amount of force it moves out a ways. When that force is released it swings back to its natural state. By observing how far it’s pushed, scientists have been able to determine the true elasticity in nature and the force required to move the stretch polymer.
The flaw in the existing standard model was discovered to be rather significant. In fact, when attempting to simulate short DNA strands using the model, strands as short as 1.3 microns (1300 nanometers) were off by about 10%. Even shorter strands half that size were off by about 18%. The shorter the strand, the more pronounced the error. Typical human DNA strands would be about 2 meters in length if stretched out end to end, but it’s the sectional components within the DNA which are affected most by these models and not the entire structure.
The new model will allow an accuracy in single-molecule research so profound that it could pave the way for a new international standard in picoforces. It could also increase accuracy enough to enable new scientific discoveries in chemistry and biology. New medical treatments, a better understanding of the way viruses invade cells and move about or replicate could be found. All of these areas of research could benefit from having the better model.