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DE-FG02-08ER46539: Electrostatics and Elasticity in Self-Assembled Nanostructures

Award Status: Active
  • Institution: Northwestern University, Chicago, IL
  • DUNS: 160079455
  • PM: Markowitz, Michael
  • Most Recent Award Date: 05/06/2021
  • Number of Support Periods: 13
  • PI: Olvera de la Cruz, Monica
  • Current Budget Period: 07/01/2021 - 06/30/2022
  • Current Project Period: 07/01/2020 - 06/30/2023
  • Supplement Budget Period: N/A

Public Abstract


Electrostatic Driven Self-Assembly of Functional Nanostructures

PI: Monica Olvera de la Cruz, Northwestern University

Co-PI: Michael Bedzyk, Northwestern University

Living cells contain a variety of molecules capable of self-organizing into aggregates to perform specific functions. Biomolecules, including proteins and lipids, can be co-assembled with synthetic molecules that mimic biomolecules into complex structures. These structures assemble and dissemble when the environment, including the concentration of the components and the ionic strength of the solution change. To mimic biomolecular functionalities and understand the organization of molecules in living systems, the investigators for this project propose to design and characterize various assemblies of charged and chiral molecules that mimic biological assemblies. The team of computational and experimental scientists will use these molecules as well as mutated proteins to organize proteins into specific structures that facilitate the catalytic activity of enzymes. Specifically, the design of amphiphilic molecules with different aminoacidic head groups and hydrophobic tails will be organized into complex architectures, which are observed in biological systems including sheets rolled up into closed tubes or into open snail shell structures, termed cochleates. Transformations between different morphologies will be triggered by modifying intermolecular electrostatic interactions via changes in the ionic conditions of the solution that contains the molecules of interest. Assemblies of proteins with amphiphiles will be achieved by adsorbing globular proteins with complex shapes that also have polar, charged and non-polar (i.e., hydrophobic and hydrophilic) surface domains onto lipid bilayers. These bilayers will be designed to have specific charge densities to favor protein adsorption. The goal is to learn to control the organization, including orientation and packing density of proteins on surfaces with different surface charge densities. The team will also analyze assemblies of proteins into microcompartments. Microcompartments are found in a wide variety of bacterial species. They are involved in breaking down nutrients with the release of energy. The shell, which is made by proteins, and the cargo self-assemble using different pathways. Theoretical and computational models will be developed to understand how assemblies of different proteins organize into sheets, tubes, and polyhedral microcompartments as a function of the properties of the proteins such as surface charge density and distribution of hydrophobic and polar groups and the concentrations of different proteins in the presence and in the absence of cargo. The basic science questions that will be addressed include how the molecular organization affects the elastic properties of the assemblies and the resulting mesoscale structures. In addition, these studies will reveal how to control the assemblies by modifying the fundamental interactions, including electrostatic interactions and how the chirality of the molecules and assemblies affect the stability of mesoscale structures.

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