IDBR: Development of New Microfluidic Mixers for the Study of Protein Folding using Optical Spectroscopy

Michigan State University, East Lansing MI

Investigators

Abstract

A grant has been awarded to Dr. Lisa Lapidus (PI) at Michigan State University and Dr. Olgica Bakajin (co-PI) at University of California, Davis for development of new microfluidic devices and optical instrumentation for use in observation of protein folding. These devices will take advantage of fluid dynamics on micron dimensions in which turbulence is suppressed and will allow observation of folding steps from 1 microsecond to about 1 millisecond. In this project we intend to develop two new microfabricated mixers and couple them to optical instruments that measure fluorescence, circular dichroism and intramolecular diffusion. One mixer will heat a protein solution to cause unfolding then rapidly mix (within 10 microsecond) with a colder solution to prompt refolding; this mixer will be used in conjunction with already existing fluorescence instrumentation. The second mixer will be a deep channel rapid mixer for instruments that require a pathlength of ¡Ý100 micrometers. This mixer will be coupled with two optical absorption techniques: 1) Tryptophan triplet quenching by cysteine to measure intramolecular contact formation and 2) Far UV circular dichroism to measure secondary structure. The field of protein folding has long been limited by experimental methods to observe folding on the microsecond timescale. This time regime is crucial to understanding early steps in the folding process and possible misfolding and aggregation mechanisms. While this instrumentation has been specifically developed to understand protein folding, many aspects of this work will be applicable to the broader fields of biochemistry and molecular biology. Rapid mixing technology coupled to standard optical instrumentation could be seamlessly adopted by researchers. Furthermore, the graduate students and postdoctoral fellows involved in this research will receive interdisciplinary training at both Michigan State University and Lawrence Livermore National Laboratories to fabricate the mixers and construct the optical instruments and will gain valuable skills in long-distance, team-based research.