Modulation of Peptide–Graphene Interfaces via Fatty Acid Conjugation

Abstract

Materials‐binding peptides have the capability to specifically recognize 2D nanomaterials and their modification via covalent attachment of nonnatural moieties offers exciting under‐explored possibilities to tune and exploit this recognition property. Here, an integrated suite of experimental approaches is used to reveal how conjugation of a fatty‐acid chain modifies surface adsorption of a graphene‐binding peptide, P1, achieved using quartz crystal microbalance measurements to access biomolecule adsorption free energies at the aqueous graphene interface, atomic force microscopy to investigate the overlayer morphologies, and circular dichroism spectroscopy to probe peptide secondary structures in the unadsorbed state. To complement these data, replica‐exchange with solute tempering molecular dynamics simulations predict the conformations of these biomolecules in both the surface‐bound and unbound states. Conjugation of the fatty acid dramatically modifies the surface‐adsorbed conformations. However, these conformational changes do not lead to substantial differences in the graphene binding strengths for each of the biomolecules studied, due to enthalpic/entropic compensation arising from changes to the contributions of peptide/graphene, peptide/fatty acid, and fatty acid/graphene interactions. These findings provide a fundamental basis for guiding future modification of materials‐binding peptides to adapt their binding propensities for applications using 2D nanomaterials.

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

“…This suggests that the addition of the fatty acid does not substantially affect the exfoliation process, regardless of its position within the peptide structure; however, it does result in a slight reduction of graphene production. Such results are consistent with binding affinities of the three molecules on graphene, where the fatty acid-modified biomolecules had slightly lower affinity for graphene than the P1 …”

“…To probe the effect of the ligand, the parent P1 peptide was modified by a 10-carbon chain fatty acid at either the N- or C-terminus (termed F 10 CP1 and P1CF 10 , respectivelyScheme ). For this, the fatty acid was modified to present a maleimide group, which was coupled directly to the thiol moiety of a cysteine residue synthetically integrated into the peptide at the appropriate terminus, following previously described methods. , Once prepared, the materials were purified and confirmed via MALDI-TOF mass spectrometry.…”

“…For this, the fatty acid was modified to present a maleimide group, which was coupled directly to the thiol moiety of a cysteine residue synthetically integrated into the peptide at the appropriate terminus, following previously described methods. 19,27 Once prepared, the materials were purified and confirmed via MALDI-TOF mass spectrometry.…”

Tailoring Peptide Self-Assembly and Formation of 2D Nanoribbons on Mica and HOPG Surface

“…Compared with mica, HOPG has no polarity at all and has good electrical conductivity [ 20 ]. Furthermore, peptides have been proven to be able to combine with a variety of functional nanomaterials, such as graphene [ 21 ], metal organic frameworks [ 22 ], MXene [ 23 ], cellulose [ 24 ], etc., due to their tunable surface groups. Peptides are often effectively combined with other functional materials through interactions such as hydrogen bonds, electrostatic interactions, and hydrophilic/hydrophobic interactions [ 25 ].…”

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

“…[11,17,18] Fatty-acid modification on either the N-or C-terminal of P1 also binds graphene strongly and brings similar exfoliation outcomes along with significant reduction of sheet damage, proposed to be conferred via edge-wrapping mechanisms. [11,19] However, the use of peptide-based approaches is not limited to exfoliation and dispersion, since peptides can also be adapted to organize and activate these 2D materials for integration into, for example, sensors, photonics, and biomedical devices. For example, peptide-based superstructures with welldefined self-assembled peptide nanofibers adsorbed onto graphene oxide (GO) have shown high stability/sensitivity for electrochemical sensing of H 2 O 2 .…”