Modular, self‐assembling peptide linkers for stable and regenerable carbon nanotube biosensor interfaces

Abstract

As part of an effort to develop nanoelectronic sensors for biological targets, we tested the potential to incorporate coiled coils as metallized, self-assembling, site-specific molecular linkers on carbon nanotubes (CNTs). Based on a previously conceived modular anchor-probe approach, a system was designed in which hydrophobic residues (valines and leucines) form the interface between the two helical peptide components. Charged residues (glutamates and arginines) on the borders of the hydrophobic interface increase peptide solubility, and provide stability and specificity for anchor-probe assembly. Two histidine residues oriented on the exposed hydrophilic exterior of each peptide were included as chelating sites for metal ions such as cobalt. Cysteines were incorporated at the peptide termini for oriented, thiol-mediated coupling to surface plasmon resonance (SPR) biosensor surfaces, gold nanoparticles or CNT substrates. The two peptides were produced by solid phase peptide synthesis using Fmoc chemistry: an acidic 42-residue peptide E42C, and its counterpart in the heterodimer, a basic 39-residue peptide R39C. The ability of E42C and R39C to bind cobalt was demonstrated by immobilized metal affinity chromatography and isothermal titration calorimetry. SPR biosensor kinetic analysis of dimer assembly revealed apparent sub-nanomolar affinities in buffers with and without 1 mM CoCl2 using two different reference surfaces. For device-oriented CNT immobilization, R39C was covalently anchored to CNT tips via a C-terminal cysteine residue. Scanning electron microscopy was used to visualize the assembly of probe peptide (E42C) N-terminally labeled with 15 nm gold nanoparticles, when added to the R39C-CNT surface. The results obtained open the way to develop CNT tip-directed recognition surfaces, using recombinant and chemically synthesized chimeras containing binding epitopes fused to the E42C sequence domain.

Quantum Mechanical Quantification of Weakly Interacting Complexes of Peptides with Single-Walled Carbon Nanotubes

“…Figure 5 shows the total DOS of the B3/(8,0) CNT. For the B3/ metallic (5,5) CNT (not shown here), we find that the total DOS of the system preserves the DOS features of pristine (5,5) tube, and there isn't obvious new DOS induced near the Fermi level. But we find different binding features when B3 interacts with semiconducting (8,0) CNT.…”

Theoretical Studies on Formation, Property Tuning and Adsorption of Graphene Segments

“…SW-CNTs have potential for biological applications ranging from biomedical sensors to drug delivery (Martin and Kohli 2003;Li, Ng et al 2005;Contarino, Sergi et al 2006). Yet, such biological applications have, so far, been limited due to two major obstacles: hydrophobicity and conformational heterogeneity.…”

Selbstorganisation von Coiled‐Coils in der synthetischen Biologie: Inspiration und Fortschritt

“…2) Die intra-und interhelicalen, nichtkovalenten Wechselwirkungen sind verhältnismäßig gut verstanden. 3) Sie können sich in niedriger Konzentration (sub-nanomolar) [71] durch Selbstorganisation zu stabilen Strukturen zusammenlagern. 4) Sie können am N-oder am C-Terminus oder über lösungsmit-telexponierte Aminosäurereste funktionalisiert werden.…”

“…Daneben waren die Dimere auch in der Lage, Cobalt mithilfe von Histidinylresten zu chelatisieren. [71] Das Ziel solcher Studien ist die Erzeugung einer Schnittstelle bestehend aus elektrisch leitfähigen Kohlenstoffnanoröhren, die lösliche biomolekulare Analyte detektieren können.…”

“…Reversible Beschichtung von Kohlenstoffnanoröhren mit Goldnanopartikeln durch Coiled-Coil-Wechselwirkungen; Aufbauprinzip (links) und rasterelektronenmikroskopische Aufnahme (rechts). [71] Abbildung 20. Durch die Fusion eines natürlichen Keratinpeptids mit einer Zellbindungsdomäne lassen sich die Eigenschaften eines Keratinhydrogels modifizieren.…”