Dissertations, Theses, and Capstone Projects

Date of Degree

6-2021

Document Type

Dissertation

Degree Name

Ph.D.

Program

Chemistry

Advisor

Rein V. Ulijn

Advisor

Xi Chen

Committee Members

Hiroshi Matsui

Donna McGregor

Subject Categories

Biotechnology | Other Life Sciences

Keywords

water-responsive, peptide, evaporation energy, humidity-responsive, peptide crystals

Abstract

Water-responsive (WR) materials  that exert significant forces in response to changing hydration levels are receiving growing interest due to their potential applications, including use as actuators for energy harvesting devices, artificial muscles, and soft robotics. Reported examples include biological and synthetic materials with abilities to efficiently convert the chemical potential of water into mechanical actuations. However, these systems are typically complex, and consequently, their WR mechanisms are not well-understood thus preventing rational design and optimization. This thesis demonstrates the design and development of WR peptide crystals that mimic and enhance understanding of natural WR systems. The peptide crystals, with intrinsic water channels in nanoscale, have the ability to swell and shrink in response to changes in relative humidity (RH), and their WR behavior is strongly dictated by their building blocks’ chemical nature and consequent organization. The crystals also exhibit outstanding mechanical properties, structural stability, and high energy density.

The modulation of peptide-sequence-dependent properties allowed us to identify key parameters that contribute to functionality during transition processes, such as dual network domains, the importance of structured water, and strengthening of hydrogen bonds, hierarchical order, order/disorder domains, and intrinsic porosity. These findings open up a magnitude of possibilities for programing simple, bioinspired peptide materials.

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