Institute of Physics, Academia Sinica

Polymer Physics and Complex Fluids Group


How to make a molecule move faster when it is in a more crowded environment ?

We put lambda DNA molecules in a 70nm high nanoslit device with a hexagonal micropost array. The posts are 3 micron in diameter, and the gap between posts vary from 1 to 4 microns. On the left, the gap size is 4 microns, and the DNA molecules adsorb to a single post. On the right, the gap size is 1 micron, and the DNA conformation fluctuates, which allows it to reach neighboring posts and move away.

We deigned an attractive micropost device to test DNA transport in a crowded environment. We found with the right amount of attraction, DNA molecules diffuse faster in more crowded arrays. This phenomena may be utilized to separate longer polymer molecules under weak flow.

Chien FT et al, (2016) Crowding-facilitated macromolecular transport in attractive micropost arrays, Scientific Report, 7, 1340.

W. Chien and Y.-L. Chen* (2016) Abnormal polymer transport in crowded attractive micropost arrays, Soft Matter, 12, 7969.