Controlling the Surface Chemistry of Graphite by Engineered Self-Assembled Peptides

Abstract

The systematic control over surface chemistry is a long-standing challenge in biomedical and nanotechnological applications for graphitic materials. As a novel approach, we utilize graphite-binding dodecapeptides that self-assemble into dense domains to form monolayer thick long-range ordered films on graphite. Specifically, the peptides are rationally designed through their amino acid sequences to predictably display hydrophilic and hydrophobic characteristics while maintaining their self-assembly capabilities on the solid substrate. The peptides are observed to maintain a high tolerance for sequence modification, allowing the control over surface chemistry via their amino acid sequence. Furthermore, through a single step co-assembly of two different designed peptides, we predictably and precisely tune the wettability of the resulting functionalized graphite surfaces from 44 to 83 degrees. The modular molecular structures and predictable behavior of short peptides demonstrated here give rise to a novel platform for functionalizing graphitic materials that offers numerous advantages, including non-invasive modification of the substrate, bio-compatible processing in an aqueous environment, and simple fusion with other functional biological molecules.

Selective Detection of Target Proteins by Peptide‐Enabled Graphene Biosensor

“…In order to prevent non-specifi c adsorption of BSA, we employed the SS-GrBP5 mutant (Table 1 ), identifi ed in an earlier study as a mutation of GrBP5 that is capable of assembling into ordered monolayers and presenting hydrophilic chemistry on the surface (e.g., 36 o contact angle at 100% coverage). [ 52 ] Such a contact angle value is similar to those achieved in literature by self-assembled monolayer polyethylene glycol anti-fouling systems (about 32 o ). [ 43,55,56 ] The contact angle value has been strongly linked to anti-fouling properties in a variety of systems.…”

“…The sensogram shows robust detection of binding at 50 ng/ml, followed by increased binding with overall resistance shift of almost 200kΩ at 10 μg/ml, probably due to the formation of a multi‐layer film. In order to prevent non‐specific adsorption of BSA, we employed the SS‐GrBP5 mutant (Table ), identified in an earlier study as a mutation of GrBP5 that is capable of assembling into ordered monolayers and presenting hydrophilic chemistry on the surface (e.g., 36 o contact angle at 100% coverage) . Such a contact angle value is similar to those achieved in literature by self‐assembled monolayer polyethylene glycol anti‐fouling systems (about 32 o ) .…”

“…Having a modular structure, the wild‐type (GrBP5‐WT) peptide can be designed to expose predictable surface chemistry through the display of specific amino acids, making it ideal for presenting molecular probes, ligands, anti‐bodies, and other sensing molecules in a controllable fashion (Figure A). Moreover, it has been shown that two mutants of GrBP5‐WT can be simultaneously assembled to display a combination of properties on the graphitic substrate . Multi‐functionality is critical to the application of a biomarker sensor in clinical practice, since in addition to possessing sensitivity, it must be capable of discriminating for the target against a background of proteins present in the sample.…”

“…Moreover, it has been shown that two mutants of GrBP5-WT can be simultaneously assembled to display a combination of properties on the graphitic substrate. [ 52 ] Multi-functionality is critical to the application of a biomarker sensor in clinical practice, since in addition to possessing sensitivity, it must be capable of discriminating for the target against a background of proteins present in the sample. It is, therefore, essential to simultaneously impart targeting and anti-fouling capabilities to the sensor.…”

Concise Review: Carbon Nanotechnology: Perspectives in Stem Cell Research

“…Whereas graphite has been extensively used in industry (lubricants, batteries, the aerospace and automobile industries, etc.) [13], few reports have suggested biological applications, for instance, in surface chemistry modification studies [19]. In contrast, fullerenes, especially graphene and carbon nanotubes, have generated tremendous interest in many fields.…”