Levich Institute Seminar Announcement, 09/08/2009
Tuesday, 09/08/2009
2:00 PM
Steinman Hall, Room #312
(Chemical Engineering Conference Room)

Professor Raymond Tu
City College of CUNY
Department of Chemical Engineering

"Periodic Peptides Assembling at Interfaces"


In nature, biological molecules form interfaces that assemble patterns of chemical functionality with exceptional precision. The role of dynamics during the assembly of biological molecules appears to be very important for processes such as biomineralization. Our work applies periodically sequenced sheet-forming peptides at interfaces to explore the dynamics of assembly in order to template mineral growth. The peptide molecules are rationally designed to have amphiphilic properties and a propensity for sheet like secondary structure. These designed peptides are deposited at the air water interface to explore the dynamics of their self-assembly and investigate their 2D order. To characterize the phase behavior, techniques such as Langmuir Blodgett and Brewster Angle Microscopy are used. Thermodynamic analysis of structure formation with increasing pressure allows us to understand the nature of self-assembly with iterative changes in the peptide sequence. Additionally, we look at the dynamics of the self-assembled state, where the organic phase switches between short- and long-range order as a function of surface pressure. This model system allows us to explore our underlying hypothesis that the time scale of the phase-transitions of the peptide at the interface defines the length-scale of the crystalline phase. This is in contrast to a system that starts with a well-ordered preformed template that defines the epitaxial growth of the mineral phase. Versions of our model peptides are modified to include histidine in order to nucleate Au nanocrystals in both the short and long range ordered organic matrix.


Raymond Tu is an assistant professor in the chemical engineering department at The City College of New York - CUNY. Dr. Tu received his PhD from the University of California - Santa Barbara in chemical engineering. After postdoctoral work at the Georgia Institute of Technology where he investigated biomolecular self-assembly using microrheology, he joined the City College faculty in 2006.