The Orientations of Large Aspect‐Ratio Coiled‐Coil Proteins Attached to Gold Nanostructures

Abstract

Methods for patterning biomolecules on a substrate at the single molecule level have been studied as a route to sensors with single-molecular sensitivity or as a way to probe biological phenomena at the single-molecule level. However, the arrangement and orientation of single biomolecules on substrates has been less investigated. Here, the arrangement and orientation of two rod-like coiled-coil proteins, cortexillin and tropomyosin, around patterned gold nanostructures is examined. The high aspect ratio of the coiled coils makes it possible to study their orientations and to pursue a strategy of protein orientation via two-point attachment. The proteins are anchored to the surfaces using thiol groups, and the number of cysteine residues in tropomyosin is varied to test how this variation affects the structure and arrangement of the surface-attached proteins. Molecular dynamics studies are used to interpret the observed positional distributions. Based on initial studies of protein attachment to gold post structures, two 31-nm-long tropomyosin molecules are aligned between the two sidewalls of a trench with a width of 68 nm. Because the approach presented in this study uses one of twenty natural amino acids, this method provides a convenient way to pattern biomolecules on substrates using standard chemistry.

DFT and SERS Study of l-Cysteine Adsorption on the Surface of Gold Nanoparticles

“…The strong adsorption of cysteine on the gold surface has been widely used in many fields. Proteins or DNA strands can be attached to gold nanostructures through cysteine–gold interactions . These modified metallic surfaces may find significant technological applications in chemical-specific detection, sensing, and catalysis .…”

“…So, it is necessary to have a better understanding of the molecular properties of the adsorption of cysteine and other amino acids on metal surfaces, and in fact, many theoretical or experimental works have been reported. , Canepa et al have studied the vapor-phase deposition of l -cysteine ( l -cys) on the Au(110) surface by means of synchrotron-based techniques, X-ray photoemission, and CK-shell X-ray absorption spectra, and the molecules were found to lay flat on the surface with both the C β –S bond and the carboxylic group almost parallel to the surface . Graff et al reported the adsorption of enantiomeric and racemic cysteine on a silver electrode–SERS sensitive to chirality of the adsorbed molecules .…”

“…Proteins or DNA strands can be attached to gold nanostructures through cysteine−gold interactions. 1 These modified metallic surfaces may find significant technological applications in chemical-specific detection, sensing, and catalysis. 2 For example, gold nanostars coated with cysteine were synthesized and applied in surface enhanced Raman spectroscopy (SERS)-based copper ions (Cu 2+ ) detection in aqueous media.…”

Controlling Association and Separation of Gold Nanoparticles with Computationally Designed Zinc-Coordinating Proteins

“…Moreover, proteins can be stable in a wide array of solvent conditions and can be tuned for stability in a chosen salt and pH environment. Work has proceeded in this area by combining NPs with well-structured natural proteins to control the assembly of NPs, − develop sensors of metal ions and biological molecules, , and modulate enzymatic and biological activity. , Protein–NP systems can leverage the structures and functions of proteins to realize association of nanoparticles in one, two, and three dimensions. − Proteins adhered to nanoparticles have been used to control NP assembly via association of their unfolded states. , Electrostatic interactions involving proteins and nanoparticles have also been used to control NP association. , Specific, selective interactions involving proteins attached to nanoparticles can confer nanoparticle association, e.g., using antigen–antibody pairs , and biotin–streptavidin systems . With protein-functionalized nanoparticles, association can be controlled via variation of pH, ,, electrostatic interactions, and relative concentrations of peptides and nanoparticles .…”