Molecular-Level Understanding of Enzyme-Surface Interactions on Complex Surfaces and Its Impact on Sensing Uranyl Cations
Abstract
This research will study interactions between immobilized enzymes and real-world polymer surfaces. Immobilized enzymes are useful as biosensors, antifouling coatings, food packaging materials and in fuel cells. However, in many cases, after surface immobilization, enzymes lose their activity due to unfavorable interactions with surfaces. Therefore, to optimize the activity and sensitivity of the immobilized enzymes, it is necessary to understand how enzymes interact with surfaces. In this study, we will use polymer surfaces with various reactive chemical groups that can link to enzymes to the surface. We can vary the chemistry of the polymer to adjust the distance between enzyme molecules and how closely they are bound to the surface. We can also vary the interactions between enzymes and polymer surfaces by varying surface hydrophobicity, and electrostatic charge which are known to have important effects on enzyme activity and stability. After immobilizing the enzymes onto CVD polymer surfaces, we will characterize enzyme structures using advanced spectroscopic techniques and computational simulations. One major tool which will be applied in this study is a nonlinear optical spectroscopic technique, called sum frequency generation (SFG) vibrational spectroscopy. SFG has a monolayer surface sensitivity which can selectively probe surface immobilized enzymes. We have shown that by using a combined SFG and computer simulations, we can successfully characterize molecular structures of surface immobilized enzymes. From the structural studies on surface immobilized enzymes, along with the biochemical characterizations, we will obtain fundamental understanding of how protein-surface interactions affect structure, stability and activity of an immobilized enzyme. Based on these fundamental studies we will then apply this knowledge to develop an enzymatic system to detect uranyl cation, the most common form of uranium found in the environment. By carefully designing and engineering the enzyme, and optimizing the enzyme-surface interactions, we aim to detect uranyl compounds with excellent sensitivity and selectivity. This joint research will be performed by Prof. Zhan Chen’s group, which has expertise in advanced spectroscopic characterization of bio-interfaces, Prof. Neil Marsh’s group, which has extensive experience in enzyme engineering, and Prof. Joerg Lahann’s group, which has expertise in rational design of polymer surfaces for enzyme immobilization and characterization. The fundamental knowledge gained on interactions between enzymes and polymer surfaces and the methodology developed to use immobilized enzymes to detect uranyl ions will be very useful for developing other biological systems capable of detecting various chemical and biological warfare agents in the future.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- May 26, 2016
- Source ID
- HDTRA11610004
Entities
People
- Zhan Chen
Organizations
- Defense Threat Reduction Agency
- University of Michigan