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Title: Concentration-Driven Assembly and Sol–Gel Transition of π-Conjugated Oligopeptides

Advances in supramolecular assembly have enabled the design and synthesis of functional materials with well-defined structures across multiple length scales. Biopolymer-synthetic hybrid materials can assemble into supramolecular structures with a broad range of structural and functional diversity through precisely controlled noncovalent interactions between subunits. Despite recent progress, there is a need to understand the mechanisms underlying the assembly of biohybrid/synthetic molecular building blocks, which ultimately control the emergent properties of hierarchical assemblies. Here in this work, we study the concentration-driven self-assembly and gelation of π-conjugated synthetic oligopeptides containing different π-conjugated cores (quaterthiophene and perylene diimide) using a combination of particle tracking microrheology, confocal fluorescence microscopy, optical spectroscopy, and electron microscopy. Our results show that π-conjugated oligopeptides self-assemble into β-sheet-rich fiber-like structures at neutral pH, even in the absence of electrostatic screening of charged residues. A critical fiber formation concentration c fiber and a critical gel concentration c gel are determined for fiber-forming π-conjugated oligopeptides, and the linear viscoelastic moduli (storage modulus G' and loss modulus G") are determined across a wide range of peptide concentrations. These results suggest that the underlying chemical structure of the synthetic π-conjugated cores greatly influences the self-assembly process, such that oligopeptides appended to π-conjugated coresmore » with greater torsional flexibility tend to form more robust fibers upon increasing peptide concentration compared to oligopeptides with sterically constrained cores. Overall, our work focuses on the molecular assembly of π-conjugated oligopeptides driven by concentration, which is controlled by a combination of enthalpic and entropic interactions between oligopeptide subunits.« less
Authors:
 [1] ;  [2] ;  [1] ; ORCiD logo [3] ;  [4] ; ORCiD logo [5] ; ORCiD logo [6]
  1. Univ. of Illinois, Urbana-Champaign, IL (United States). Dept. of Materials Science and Engineering
  2. Univ. of Illinois, Urbana-Champaign, IL (United States). Dept. of Chemical and Biomolecular Engineering
  3. Johns Hopkins Univ., Baltimore, MD (United States). Dept. of Chemistry
  4. Univ. of Illinois, Urbana-Champaign, IL (United States). Frederick Seitz Materials Research Lab.; Harvard Univ., Cambridge, MA (United States). Center for Nanoscale Systems
  5. Johns Hopkins Univ., Baltimore, MD (United States). Dept. of Chemistry; Johns Hopkins Univ., Baltimore, MD (United States). Dept. of Materials Science and Engineering
  6. Univ. of Illinois, Urbana-Champaign, IL (United States). Dept. of Chemical and Biomolecular Engineering; Univ. of Illinois, Urbana-Champaign, IL (United States). Dept. of Materials Science and Engineering
Publication Date:
Grant/Contract Number:
SC0011847
Type:
Published Article
Journal Name:
ACS Central Science
Additional Journal Information:
Journal Volume: 3; Journal Issue: 9; Journal ID: ISSN 2374-7943
Publisher:
American Chemical Society (ACS)
Research Org:
Univ. of Illinois, Urbana-Champaign, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 36 MATERIALS SCIENCE; 77 NANOSCIENCE AND NANOTECHNOLOGY
OSTI Identifier:
1375504
Alternate Identifier(s):
OSTI ID: 1421386