CAREER: Understanding Multivalent Biological Bonds for Biosenssing Applications
This project?s research goal is to understand multivalent biological bonds, the simultaneous interaction of multiple ligands with multiple receptors, in order to improve the fields of medicine and bioengineering. Multivalent bonds underpin a variety of biological and biotechnological processes, including cell/tissue adhesion and antibody/therapeutic targeting. However, there is currently no coherent description of multivalent binding which can predict the strength of multivalent interactions and understand the rapid intermediate binding states that may result due to the fluctuations of individual molecular bonds.
The research goals will be pursued in a basic science study of the adhesion of a remarkable form of antibody derived from the lamprey eel: the variable lymphocyte receptor. Variable lymphocyte receptor antibodies are highly multivalent and have a well-defined and easily modified structure. Moreover, the antibodies offer several exciting possibilities for biosensor advancement, including high binding affinity with an easy method for varying that affinity as well as incredible environmental stability.
The research objectives will be to first create well-defined, multivalent constructs of antibodies. The antibodies will be molecularly engineered to vary the valency and the linker architecture. Second, the bond strength will be measured as valency and linker structure are varied. The bond strength will be measured with a complementary suite of analytical techniques including surface plasmon resonance as well as single-molecule adhesion techniques based upon atomic force microscopy. Force spectroscopy will be used to measure the kinetics of the multi-step multivalent transitions?a capability that is uniquely suited to single-molecule measurements. Third, these measurements will then test the predictions of a new theoretical model describing multivalent binding.
The education objectives of this proposal will be to create a cross-disciplinary science fair for an Atlanta public high school; design and implement outreach curricula in an Atlanta elementary school that focus on hands-on science enrichment; and integrate the concepts of biological multivalency into lessons for the Biologically Inspired Design Projects Laboratory at Georgia Tech.
Intellectual merit of this research will be to test the hypothesis that multivalent bonds dramatically increase binding strength through a decrease in multi-state dissociation kinetics and that the kinetics of dissociation are radically controlled by adjusting the physical properties and architecture of the linker between multiple antigen binding sites. This research may explain an intriguing question: why have researchers shown such a wide a range of multivalent affinity increase, from 101-1010 fold?
The broader impacts of the fundamental understanding of biomolecular adhesion at micro- and nano-interfaces may also improve sensor operation by identifying design principles for highly efficient multivalent binding. Biomolecular interactions can then be tailored to show a wide variety of binding strengths and perhaps sensitivities to near neighbors of a targeted microbial strain. Such capabilities will greatly improve biosensors by reducing the cost and complexity of biosensors while increasing their reliability. Ultimately, this basic science research study will create detection technologies with higher stability, specificity, and sensitivity than can be currently achieved and at the same time provide cross-disciplinary training and education to students at Georgia Tech and local area schools.
