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

Abstract

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 cores with greatermore » 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:

Zhou, Yuecheng; Li, Bo; Li, Songsong; Ardoña, Herdeline Ann M. ;

• Search DOE PAGES for author "Ardoña, Herdeline Ann M."
• Search DOE PAGES for ORCID "0000-0003-0640-1262"
• Search orcid.org for ORCID "0000-0003-0640-1262"

Wilson, William L. ^[1]; Tovar, John D. ;

• Search DOE PAGES for author "Tovar, John D."
• Search DOE PAGES for ORCID "0000-0002-9650-2210"
• Search orcid.org for ORCID "0000-0002-9650-2210"

Schroeder, Charles M.

• Search DOE PAGES for author "Schroeder, Charles M."
• Search DOE PAGES for ORCID "0000-0001-6023-2274"
• Search orcid.org for ORCID "0000-0001-6023-2274"

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+ Show Author Affiliations

1. Center for Nanoscale Systems, Faculty of Arts and Sciences, Harvard University, Cambridge, Massachusetts 02138, United States

Publication Date:

2017-08-17

Research Org.:

Univ. of Illinois at Urbana-Champaign, IL (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1375504

Alternate Identifier(s):

OSTI ID: 1421386

Grant/Contract Number:  

SC0011847

Resource Type:

Published Article

Journal Name:

ACS Central Science

Additional Journal Information:

Journal Name: ACS Central Science Journal Volume: 3 Journal Issue: 9; Journal ID: ISSN 2374-7943

Publisher:

American Chemical Society (ACS)

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 36 MATERIALS SCIENCE; 77 NANOSCIENCE AND NANOTECHNOLOGY