Watching Molecules Hop

Published: June 1, 2014
Dan Schwartz and Blake Langdon in lab

Surfaces and interfaces influence molecular and macroscopic phenomena in fields ranging from pharmaceuticals to biofuel catalysis to biomedical devices. A powerful way to understand these effects is to literally watch individual molecules move around on surfaces, something that has not been possible until now.

Department Chair and Alfred T. and Betty E. Look Professor Dan Schwartz and his research group have developed a method to dynamically track single molecules using total internal reflection fluorescence microscopy (TIRFM), and their results are surprising.

“Traditionally, molecules were thought to move on surfaces via a continuous two-dimensional random walk, analogous to the Brownian motion of dust particles one sees in a beam of sunlight. Instead, we have found that molecules actually engage in intermittent hopping from location to location on the surface” explains Schwartz.

“This means that molecules can explore a surface much more efficiently than previously thought, which has important implications for catalysis and bio-sensing in particular. Interestingly, a very similar type of motion has evolved in seabirds and other foraging animals that search for sparsely-distributed resources.”

The applications of single-molecule TIRFM for the better design of non-fouling materials and coatings for filters, packaging, drugs, foods and medical devices earned Schwartz recognition in the 2014 NSF Compendium of Technological Breakthroughs. Recent publications by Schwartz’s group have led to important advances in DNA-based biotechnologybiomaterials and polymer coating/lubrication, further illustrating the widespread relevance of this research.

While Schwartz’s research has always been in interfacial science, his academic background is grounded in chemistry and physics. He moved to CU from Tulane University in 2001 because “CU’s ChBE department had a strong focus on both collaborative research and teaching, and a group of people that got along well and had ambition for the department’s future.”

Schwartz collaborates with many researchers both in and outside of the department.

Schwartz believes moving from fundamental science to engineering has increased the impact of his research. “My research cuts across many fields, so research-wise it is a good fit to be in chemical engineering. As time has passed, I have developed a greater appreciation of the engineering approach and have adopted it more and more. The difference is subtle, with engineering being a bit more application-oriented.”

In addition to research, Schwartz has taken on many other responsibilities. He took over as ChBE Department Chair in July of 2012 and has helmed the department’s recent move from 18th to 14th in the U.S. News & World Report top graduate program rankings. His goal is to reach the top 10 by 2020.

“I really think the keys to further success will be to continue to add really great new people to the department and to very actively promote our visibility,” he says.

Also, Schwartz was recently elected to the ACS Colloid and Surface Chemistry (COLL) Division Chair Line and will serve as Vice Chair in 2014, Chair-Elect in 2015, Division Chair in 2016 and Past Chair in 2017.

 “I really appreciate the COLL Division; they are very active in organizing research symposia that are great events for faculty and students and they oversee several important awards,” he says. “The continuing success of that group depends on people willing to step up and take the lead. These are many of the same reasons that I agreed to be chair of the department: I have always felt that I should do my share.”

As a Senior Editor for Langmuir and involvement in the NSF Liquid Crystal Materials Research Center, Schwartz has had little time for teaching the past two years --- which is why he is all the more excited to be teaching a graduate-level statistical thermodynamics class this fall.

Though difficult, Schwartz’s classes have been very well-received by students and earned him the student-presented Graduate Student Teaching Award in 2012.

“One of the things I really like about this class is that students come into it with the expectation that they will really be challenged,” says Schwartz. “I am able to ask them to struggle with really difficult concepts that help them transition from learning at the undergraduate level to more the independent approach of a graduate student.

(Pictured above: Professor Dan Schwartz and graduate student Blake Langdon use revolutionary methods such as TIRFM, Förster resonance energy transfer (FRET) tracking to elucidate changes in protein structure on surfaces at the single-molecule level.)