In the Jan. 17 issue of Science, the researchers describe an example of their new approach in which they engineered a surface that can change from water-attracting to water-repelling with the application of a weak electric field. Switch the electrical potential of that field from positive to negative and the surface reverts to its initial affinity for water.
The general technique, on which the group has filed for a patent, could also be applied to the dynamic control of other surface characteristics such as adhesion, friction and biocompatibility. We started with a fundamental system to prove that the overall concept of reversibly modifying a surface via conformational transitions works, said Thanh-Nga Tran, a graduate student in the Harvard-MIT Division of Health Sciences and Technology (HST) and the Department of Chemical Engineering.
This opens the door to a variety of applications, including novel drug-delivery systems and smart templates for the bioseparation of one molecule from another, said Robert Langer, MITs Germeshausen Professor of Chemical and Biomedical Engineering and leader of the work. Langer has appointments in chemical engineering, HST and MITs Biological Engineering Division.
This is the first time to our knowledge that anyone has created a truly reversible switch of a surfaces property exploiting monomolecular layers, said Joerg Lahann, a Postdoctoral Associate in CE. As a result, we believe this study lays the fundamental groundwork for a new paradigm in surface engineering that may be of considerable significance in materials science, biology, and medicine.