Kinetic Properties of Multicomponent Charged Systems

Arizona State University, Scottsdale AZ

Investigators

Abstract

TECHNICAL SUMMARY This award supports theoretical research and education at the interface between the physical and biological sciences. Molecular-level multicomponent aggregates are ubiquitous in biological systems. Many functional structures in living cells are multimers, and are often composed of heterogeneous units. The components of these groups are associated through physical interactions such as electrostatic attractions, hydrogen-bonding and the shielding of hydrophobic protein segments from an aqueous environment. The production and degradation of these structures can occur in equilibrium or be part of a driven process. These composites can have long life-times, even when they are not the global thermodynamic ground state of the system. Their stability arises from the presence of large activation barriers that make a more energetically-favorable disassembled state unreachable. This and many other kinetic features of biological systems invite theoretical exploration and their imitation in the construction of synthetic systems. While synthetic multicomponent systems have not achieved the degree of complexity observed in biological structures, a number of examples already exist where similar structures and methods of construction and stabilization have been successfully copied. Kinetic trapping is a well known tool of chemical and physical nanofabrication; nanoparticles and polyelectrolyte based structures are reliably formed in this way. In spite of the effectiveness of these methods of construction, they have not been fully addressed theoretically. As a result, many nanofabrication methods and structural features remain unexplored. The main goal of this research project is to theoretically understand how to imitate both structural and processing features in biological systems. In particular, the PI aims at a more precise description of instances where charged multicomponent systems remain stable within a variety of environmental changes. The PI will use novel and unexploited theoretical techniques, such as path exploration methods coupled to variational approaches. He will apply them to two main types of systems: (1) nucleosome-like structures where charged entities interact with large polyelectrolytes; and (2) assemblages of multicomponent charged structures near a charged surface. The ideas on which this work is based originated from the identification of structures and processes in biological systems. To pursue these ideas in a systematic way, the PI aims to use bioinformatic techniques to exploit biological information for synthetic purposes. He plans to query protein databases for information regarding the use of charge and shape in multicomponent systems. These questions form the basis of involvement of undergraduate researchers in the proposed investigations. It will provide them with a physical perspective to tackle biological problems of structure and function. The bioinformatic component of the project will have an impact on the education of students in the biological sciences in providing further concrete examples of the applications of physical principles and ideas useful that are useful in biological contexts. NON-TECHNICAL SUMMARY This award supports theoretical research and education at the interface between the physical and biological sciences. The PI will apply novel theoretical techniques to study biologically inspired systems to with the goal of devising methods to synthetically construct nanostructures. In essence, the PI seeks to understand how to imitate both structural and processing features in biological systems. This research focuses on understanding how to mimic biology to develop new materials and nanoscale structures that are difficult to synthesize in any other way. This is a promising area of biomaterials research that may have impact on developing new materials with desired properties for a wide range of applications. The research is structured to effectively involve undergraduate students in the research project.