Thermal Selection of Aqueous Molecular Conformations for Tailored Energetics of Peptide Assemblies at Solid Interfaces

Abstract

Key to the development of functional bioinorganic soft interfaces is the predictive control over the micron-scale assembly structure and energetics of biomolecules at solid interfaces. While assembly of labile biomolecules, such as short peptides, at interfaces is a great deal affected by the shape of the molecule, biomolecular conformations are prompted by external solution conditions, involving temperature, pH, and salt concentration. In this light, one can expect that the environmental conformational selection of aqueous biomolecules could potentially allow for fine-tuning of the equilibrium assembly structure at interfaces, as well as, the binding strength and molecular mobility within these assemblies. Here, we demonstrate the energetic and structural tailoring of two-dimensional surface assemblies of graphite-binding dodecapeptides, through the thermal selection of aqueous peptide conformations. Our findings based on a scanning probe energetic analysis, supplemented by molecular dynamics modeling, show that peptide-graphite and peptide−peptide intermolecular interactions strongly depend on the thermally selected molecular conformation and that the extent of the conformational change is directly related to the observed assembled structure. Enabled by these results was the design of a peptide with predictable binding and assembled structure, thus, suggesting environmental preconditioning of peptides as a means for controlling self-assembling active bioinorganic interfaces for bioelectronic implementations such as biomolecular fuel cells and biosensors.

Solid-Binding Peptide-Guided Spatially Directed Immobilization of Kinetically Matched Enzyme Cascades in Membrane Nanoreactors

“…Although being highly superficial, this results in slow leaching of the immobilized enzymes from the reactor bed leading to a gradual decrease in reactor efficacy. 30,33,35,36 However, even after 10 days of continuous operation at room temperature, 84.4% of the initial catalytic performance was maintained, which is significantly higher than the stabilities of LDH and FDH cascades that are reported as 55−70%, previously. 60,61 ■ CONCLUSIONS…”

“…As the enzyme introduction into the reactor was discontinued, dynamic equilibrium created at the membrane–solvent interface shifts toward dissociation due to the nature of the electrostatic interactions, e.g., electrostatic forces, van der Waals forces, hydrogen bonding, etc., formed between the peptide tag and the activated membrane surface. Although being highly superficial, this results in slow leaching of the immobilized enzymes from the reactor bed leading to a gradual decrease in reactor efficacy. ,,, However, even after 10 days of continuous operation at room temperature, 84.4% of the initial catalytic performance was maintained, which is significantly higher than the stabilities of LDH and FDH cascades that are reported as 55–70%, previously. , …”

“…Solid-binding peptides are used as the fundamental molecular building blocks to facilitate the seamless integration of inorganic solid materials with biological molecules toward the development of hybrid devices and systems. ,− These peptides are a short sequence of amino acids that were selected with affinity to inorganic solids using directed evolution techniques, such as phage display and cell surface display. , The specificity of the solid-binding peptide for a given solid, e.g., gold, silica, or graphite, stems from the physicochemical effects at the interface that involve a combination of weak interactions, including van der Waals, hydrogen bonding, and coulombic forces, as well as surface diffusion and structural changes toward establishing a stable conformation with multiple contact points creating a unique footprint on the material surface. ,,, …”

“…26,31 The specificity of the solid-binding peptide for a given solid, e.g., gold, silica, or graphite, stems from the physicochemical effects at the interface that involve a combination of weak interactions, including van der Waals, hydrogen bonding, and coulombic forces, as well as surface diffusion and structural changes toward establishing a stable conformation with multiple contact points creating a unique footprint on the material surface. 30,33,35,36 The authors and other groups have identified multitudes of solid-binding peptides that are specific to metals, ceramics, and minerals, e.g., Au, Ag, Pt, TiO 2 , SiO 2 , hydroxyapatite, and graphite. 35,37−43 Their utility as anchoring moieties facilitating immobilization of functional proteins onto solid surfaces has been demonstrated at large length scales.…”

Cosolvents Restrain Self-Assembly of a Fibroin-Like Peptide on Graphite

“…The ordered structures of peptides on the surface have been used to immobilize bioprobes for electrical biosensing, ,, and their monomolecular thickness has been found to be suitable for a good signal transduction from bioprobes to 2D materials . The uniform coverage of designed peptides on the surface is essential to control wetting of the surface of 2D materials and to prevent the active layer of 2D materials from nonspecifically binding biomolecules. , For a better understanding of surface self-assembly of peptides at the solid–liquid interface, a variety of methods for self-assembly of peptides have been studied, such as designing peptide sequences, electric fields, electrochemical stimulation, fluid control, pH effect, salt-driving effects, substrate template influence, temperature, AFM-mediated self-assembly, and seed-guided self-assembly …”