We welcomed Joerg Lahann to our faculty as an assistant professor this fall. Joerg received his Ph.D. in 1998 in macromolecular chemistry from Aachen University in Germany where he worked with Dr. Hartwig Hoecker. Most recently he has been doing postdoctoral work with Professor Robert Langer in the Chemical Engineering Department at MIT. His research is broadly related to surface engineering with strong ties to biomedical engineering and nanotechnology. He has already published over 20 scientific publications and has contributed to more than 10 patent applications. Earlier this year, his research on reversibly switching surfaces was featured in an article in Science (J. Lahann, et al., A Reversibly Switching Surface. January 17, 2003, 299, 371-374.)(described on page 5). These “smart surfaces” can reversibly switch properties in response to an external stimulus. To demonstrate these findings, a surface design was developed that can be changed from water-attracting to water repelling with the application of a weak electric field. Designed as a switch, single-layered molecular-level machines are aligned on a surface using self assembly and are then flipped between defined microscopic states. This type of surface design may offer a new paradigm for interfacial engineering as it amplifies reversible conformational transitions at a molecular level to macroscopic changes in surface properties without altering the chemical identity of the surface. Lahann has also developed a novel class of polymers with potential for biomimetic and spatially directed surface engineering. This “reactive coating” technology uses chemical vapor deposition (CVD) polymerization to deposit a wide range of chemical signatures on various substrate materials. Its simplicity in providing chemically reactive groups and its applicability to three-dimensional geometries (e.g., for microfluidics) enables the exact tailoring of surface properties and the preparation of biologically relevant microenvironments. Reactive coatings are compatible with soft lithographic processes, allowing for patterning of proteins, DNA, cytokines, and mammalian cells.

As he begins his career at Michigan, Lahann is looking forward to continuing his research of the interface between man-made materials and cellular systems. He sees the importance of both innovation and applied science in his research. “Although it is immensely important to push the fundamental boundaries of research permanently,” Lahann says, “it is equally critical not to lose sight of potential applications that may help us to justify our efforts.”

Lahann’s research featured in January 17, 2003 issue of Science Text excerpted with permission from R. Service, “Chemists Concoct Quick-Change Surface,” Science, 299:321-323 (2003). Copyright (2003) American Association for the Advancement of Science. A novel material, described in the January 17, 2003, issue of Science, has a unique love-hate relationship with water. With a flip of a switch, it alternates between attraction and repulsion. The secret to the switchable material, which scientists say could have a variety of uses, is electronically twisting molecules arrayed on the surface. Teams have been able to switch surface properties before, but only by laboriously adjusting their chemistry. Physical chemist Joerg Lahann, a former post-doctoral student in the lab of chemical engineer Robert Langer at the Massachusetts Institute of Technology, wanted something easier. Lahann and colleagues turned to chainlike polymers called alkanethiols, which naturally assemble into what looks like rows of tightly packed cornstalks. If they could synthesize alkanethiols with different chemical properties on their tops and sides and then attach them to a plate, the researchers thought, they could alter the surface properties of the plate simply by making the molecules stand straight or bend over. Getting the alkanethiols to stand up was easy. Sulfur atoms at one end of the molecules naturally bind to gold surfaces, and the molecular stalks stick straight up if packed in tightly. To bend over, however, the alkanethiols needed breathing room, which Lahann supplied by synthesizing novel alkanethiol stalks with bulky mushroom-like heads. As the surfactant-like amphiphilic molecules latched onto the gold surface, the bulky heads prevented them from packing tightly together. Lahann and his colleagues then used a standard chemical reaction to lop off the tops of the mushrooms, leaving each molecular cornstalk-tipped with a negatively charged, water-loving carboxylic acid group. To persuade molecules to bend over, Lahann and his colleagues needed only to wire up the gold surface to a power supply. When the researchers applied a positive electric potential, the plate yanked down on the carboxylic acids, exposing their water-repelling hydrocarbon chains. Photo reprinted with permission from J. Lahann et al., "A Reversibly Switching Surface," 299:317-374 (2003). Copyright (2003) American Association for the Advancement of Science.

This article originally appeared in the 2003 ChE Newsletter. Download 2003 Newsletter(PDF)