title: Nonequilibrium Self-Assembly of π-Conjugated Oligopeptides in Solution.
abstract: Supramolecular assembly is a powerful method that can be used to generate materials with well-defined structures across multiple length scales. Supramolecular assemblies consisting of biopolymer-synthetic polymer subunits are specifically known to exhibit exceptional structural and functional diversity as well as programmable control of noncovalent interactions through hydrogen bonding in biopolymer subunits. Despite recent progress, there is a need to control and quantitatively understand assembly under nonequilibrium conditions. In this work, we study the nonequilibrium self-assembly of π-conjugated synthetic oligopeptides using a combination of experiments and analytical modeling. By isolating an aqueous peptide solution droplet within an immiscible organic layer, the rate of peptide assembly in the aqueous solution can be controlled by tuning the transport rate of acid that is used to trigger assembly. Using this approach, peptides are guided to assemble under reaction-dominated and diffusion-dominated conditions, with results showing a transition from a diffusion-limited reaction front to spatially homogeneous assembly as the transport rate of acid decreases. Interestingly, our results show that the morphology of self-assembled peptide fibers is controlled by the assembly kinetics such that increasingly homogeneous structures of self-assembled synthetic oligopeptides were generally obtained using slower rates of assembly. We further developed an analytical reaction-diffusion model to describe oligopeptide assembly, and experimental results are compared to the reaction-diffusion model across a range of parameters. Overall, this work highlights the importance of molecular self-assembly under nonequilibrium conditions, specifically showing that oligopeptide assembly is governed by a delicate balance between reaction kinetics and transport processes.
authors.affiliation: Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.
authors.forename: Bo
authors.initials: B
authors.lastname: Li
authors.affiliation: Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign , Urbana, Illinois 61820, United States.
authors.forename: Songsong
authors.initials: S
authors.lastname: Li
authors.affiliation: Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign , Urbana, Illinois 61820, United States.
authors.forename: Yuecheng
authors.initials: Y
authors.lastname: Zhou
authors.affiliation: Department of Chemistry, Johns Hopkins University , Baltimore, Maryland 21218, United States.
authors.forename: Herdeline Ann M
authors.identifier: http://orcid.org/0000-0003-0640-1262
authors.initials: HA
authors.lastname: Ardoña
authors.affiliation: Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign , Urbana, Illinois 61820, United States.
authors.forename: Lawrence R
authors.initials: LR
authors.lastname: Valverde
authors.affiliation: Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign , Urbana, Illinois 61820, United States.|Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.|Center for Nanoscale Systems, Faculty of Arts and Sciences, Harvard University , Cambridge, Massachusetts 02138, United States.
authors.forename: William L
authors.initials: WL
authors.lastname: Wilson
authors.affiliation: Department of Chemistry, Johns Hopkins University , Baltimore, Maryland 21218, United States.|Department of Materials Science and Engineering, Johns Hopkins University , Baltimore, Maryland 21218, United States.
authors.forename: John D
authors.identifier: http://orcid.org/0000-0002-9650-2210
authors.initials: JD
authors.lastname: Tovar
authors.affiliation: Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.|Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign , Urbana, Illinois 61820, United States.
authors.forename: Charles M
authors.identifier: http://orcid.org/0000-0001-6023-2274
authors.initials: CM
authors.lastname: Schroeder
keywords: biohybrid materials; diffusion-controlled; nonequilibrium assembly; optoelectronic materials; reaction-controlled; supramolecular assembly; π-conjugated oligopeptides