One‐Dimensional Gold Nanoparticle Arrays by Electrostatically Directed Organization Using Polypeptide Self‐Assembly

Abstract

The study of interactions between particles organized in a linear configuration is interesting from a quantum mechanical perspective, and the anisotropic properties of linear assemblies is of potential interest for the development of solid-state devices. [1][2][3] This anisotropy may be manifested as a difference in the magnetization and coercivity obtained in a magneticnanoparticle array when a field is applied along the chain or orthogonal to it. [4,5 ] Nonlinear electrical characteristics [3] or dichroism in the optical spectra with longitudinal and transverse polarizations of light [6,7 ] in metal nanoparticle arrays are other examples of such anisotropy, and the construction of such arrays would offer opportunities in multiple applications. Engineering matter at submicron length scales has been an area largely dominated by top-down methodologies. Control of interparticle spacing in metal-nanoparticle arrays by using techniques such as electron beam lithography has been found to have a dramatic impact on the optical response of the nanoparticle assembly, [8][9][10] ] and has implications in fields such as plasmonics [11] and energy transport. [12,13 ] The use of templates such as carbon nanotubes [14] and linear pores[15] to construct one-dimensional nanostructures has been demonstrated previously. In addition, polymers have recently begun to play an increasingly active role as elements that can reproducibly direct the arrangement of nanoparticles into functional geometries. [16,17 ] Self assembling systems offer convenient yet powerful bottom-up strategies for the creation of nanostructures that can be deployed in the realization of functional nanoscale devices. [18,19 ] The utilization of biomolecules such as DNA, [3, 20 -24 ] and protein-based materials [25][26][27] or viruses [28,29 ] to dictate the organization of nanoparticles has been shown to be an effective and robust paradigm. The use of peptide-based structures [30,31 ] in nanotechnology confers numerous advantages such as the specification of assembled nanostructure by changes in the primary sequence of the peptide, as well as the adoption of various hierarchical morphologies **

Multivalent protein polymers with controlled chemical and physical properties

“…Characterization of the fibril-particle assemblies via bright-field TEM (BF-TEM; Figure 13) clearly illustrates that the gold nanoparticles are controllably immobilized on the fibrils, with successful templating over distances of hundreds of nanometers. Statistical analysis of the inter-nanoparticle spacing of the BF-TEM images yields inter-particle distances of 5.5 ± 1.2 nm, in excellent agreement with the model proposed in Figure 12 [117]. That this assembly is templated and not merely a result of electrostatically mediated deposition of the nanoparticles on a uniformly charged fibril is suggested by Debye theory.…”

“…The detailed assembly and structure of the fibrils was provided by wide angle X-ray scattering (WAXS), Fourier transform infra-red (FTIR) spectroscopy, atomic force microscopy (AFM) and optical microscopy techniques (Figure 12) [117]. In X-ray scattering, a broad peak corresponding to a d-spacing of 4.56 Å was obtained, consistent with the hydrogen-bonding distance between β-sheet strands in peptides and proteins [118,119].…”

Photoconductivity of Pea‐Pod‐Type Chains of Gold Nanoparticles Encapsulated within Dielectric Amyloid Protein Nanofibrils of α‐Synuclein

“…In particular, fabrication of anisotropic one‐dimensional noble‐metal nanoparticle chains to obtain integrated optics operating below the diffraction limit of light has garnered much attention 2. 10, 11 In fact, numerous efforts have been made to embed noble‐metal nanoparticles within dielectric matrixes in high density by employing sol–gel processes, metal‐ion implantation, and metal sputtering 12–14. Herein, we introduce a convenient bottom‐up strategy to assemble AuNPs into the one‐dimensional chain structures within a dielectric protein matrix of amyloid fibrils.…”

Peptide‐Based Biomimetic Materials

“…Negatively charged gold nanoparticles (2.0 ± 0.3 nm in diameter) were mixed with preformed peptide fi brils, resulting in periodically spaced, parallel, linear nanoparticle arrays ( Figure 6.20 b). Recently, the group of Pochan and Kiick fabricated one -dimensional gold nanoparticle chains with precise axial separations by using self -assembling polypeptide fi brils that have a unique molecular architecture with spatially repeating positively charged patches [139] . Recently, the group of Pochan and Kiick fabricated one -dimensional gold nanoparticle chains with precise axial separations by using self -assembling polypeptide fi brils that have a unique molecular architecture with spatially repeating positively charged patches [139] .…”

“…The ordered organization of nanoparticles on the two -dimensional sheets was predominately ascribed to the electrostatic interaction between negatively charged particles with the positively charged lysine residues, but was affected by multiple factors such as the nontwisted laminated morphology of a template, strong complementary interaction, and the same order between particle size and lateral spacing of the fi bril [141] . This strategy is able to be extended to construct one -dimensional arrays of different nanoparticle types and internanoparticle spacing can be modulated by programming the polypeptide sequence [139] . An alanine -rich polypeptide was precisely designed for the formation of fi brils with regularly spaced charged patches along the longitudinal axis of the fi bril.…”