Identification of Parameters Controlling Peptide-Driven Graphene Exfoliation in Aqueous Media

Abstract

Bio-inspired approaches represent potentially transformational methods to fabricate and activate non-natural materials for applications ranging from biomedical diagnostics to energy harvesting platforms. Recently, bio-based methods for the exfoliation of graphene in water have been developed, resulting in peptide-capped nanosheets; however, a clear understanding of the reaction system and peptide ligand structure remains unclear, limiting the advance of such approaches. Here the effects of reaction solution conditions and peptide ligand structure were systematically examined for graphene exfoliation, identifying key parameters to optimize material production. For this, the P1 peptide, identified with affinity for graphene, was exploited to drive exfoliation of bulk graphite to generate the final materials. The peptide was modified at both the N- and C-terminus with a 10-carbon chain fatty acid to explore the effects of a hydrophobic domain on the exfoliation process. The system was examined as a function of sonication time, pH, reagent concentration, and graphite source, where the final materials were fully characterized using a suite of approaches. Collectively, these results demonstrated that maximum graphene production was achieved using the parent P1 peptide after 12 h of sonication under basic conditions. While the exfoliation efficiency was slightly lower for the fatty acid modified peptides, the graphene produced using these biomolecules had fewer defects incorporated, potentially from the wrapping of the nanosheet edge by the aliphatic domain. Such results are important to provide key reaction designs to optimize the reproducibility of graphene exfoliation using biomimetic approaches.

Modeling‐Led Materials‐Binding Peptide Design for Hexagonal Boron Nitride Interfaces

“…[ 6–10 ] Alternatively, bio‐related strategies based on specific, noncovalent interactions between biomolecules and material surfaces have become the focus of producing those nanomaterials in aqueous media with minimal defects and under more ambient conditions. [ 11–16 ] For example, the P1 peptide, [ 17,18 ] with sequence HSSWYWAFNNKT, is one of the most studied graphene recognizing biomolecules due to its binding affinity on basal graphene. It has been previously demonstrated that using a sonication‐based exfoliation method and the P1 peptide, one can obtain exfoliated graphene with a thickness of <2 nm that remains colloidally dispersed in aqueous systems.…”

Peptide-Driven Exfoliation and Dispersion Mechanisms of Graphene in Aqueous Media

“…The topic of liquid-phase exfoliation of graphene and other 2D-layered materials in a variety of nonwater-based solvents has been a subject of numerous previous molecular simulation studies. − However, the ability to exfoliate graphene or other 2D materials in aqueous media is attractive from several perspectives. − Both nonbiological, − lipid-based, − and peptide-based ,− strategies have been recently reported for achieving this goal. In particular, biobased approaches offer the possibility to exploit the programmability of peptides and proteins to further activate, organize, and protect the exfoliated graphene sheets in aqueous solution.…”

“…In particular, biobased approaches offer the possibility to exploit the programmability of peptides and proteins to further activate, organize, and protect the exfoliated graphene sheets in aqueous solution. Previous simulations that studied the role of the peptides in exfoliation were limited to standard molecular dynamics simulations , and, more recently, nonequilibrium molecular dynamics simulations of only the initial stages of the exfoliation process under sonication conditions. , To date, no simulation data have been reported regarding quantification of the free-energy barriers associated with peptide-driven graphene exfoliation or dispersion in liquid water. Here, steered molecular dynamics simulations and umbrella sampling simulations were used to explore these two aspects, while also approximately mimicking the physical effects of sonication during exfoliation.…”

“…Here, steered molecular dynamics simulations and umbrella sampling simulations were used to explore these two aspects, while also approximately mimicking the physical effects of sonication during exfoliation. These simulations were based on a known P1-exfoliating peptide , P1, with a sequence of HSSYWYAFNNKT, which has significant affinity for the basal plane of graphene. , …”

“…Here, steered molecular dynamics simulations and umbrella sampling simulations were used to explore these two aspects, while also approximately mimicking the physical effects of sonication during exfoliation. These simulations were based on a known P1-exfoliating peptide 20,21 P1, with a sequence of HSSY-WYAFNNKT, which has significant affinity for the basal plane of graphene. 22,23 In the first stage of this work (summarized in Figure 1), a structural model of a nine-layer graphite stack was constructed and immersed in liquid water, where each sheet in the stack was ∼4.7 nm in diameter.…”