Abstract:Biomaterials derived via programmable supramolecular protein assembly provide a viable means of constructing precisely defined structures. Here, we present programmed superstructures of AuPt nanoparticles (NPs) on carbon nanotubes (CNTs) that exhibit distinct electrocatalytic activities with respect to the nanoparticle positions via rationally modulated peptide-mediated assembly. De novo designed peptides assemble into six-helix bundles along the CNT axis to form a suprahelical structure. Surface cysteine resi… Show more
“…Peptides can also be designed to assemble and coil around nanomaterial templates and present nucleation sites for the growth of inorganic NPs. Kang et al designed a composite material consisting of a carbon nanotube (CNT) surrounded by an engineered peptide . The peptide sequence was designed to assemble into helices, where one face had an affinity for the CNTs and the other would bind the inorganic NPs.…”
Section: Helical Nanoparticle Superstructures: Methods Of Constructionmentioning
Chiral objects are defined as nonsuperimposable conformations that are mirror images of each other, much like a pair of left and right hands. In fact, the word "chiral" derives from the Greek word "χειρ" (kheir), which translates to "hand." Most biomolecules exist in only one particular conformation. For example, amino acids within large protein and peptide molecules are exclusively in the l-form (left-handed). It has long been considered that the phenomenon of homochirality (predominant occurrence of one conformation) could be linked to the origin of life. [1] These phenomena have inspired chemists and biologists to isolate, synthesize, and study the properties of chiral molecules. Research interest in chiral nanostructures has escalated rapidly since the early 2000s due to visionary reports that either predicted or demonstrated the potential applications of these materials. [2,3] In 2004, Pendry predicted that chiral metamaterials could be used to achieve negative refraction (Figure 1). [2] Following this seminal work, others demonstrated that such materials lead to circular dichroism (CD), [4] negative phase velocities, [5] and intense gyrotropy, [6] generating significant excitement within this emerging field. These properties can be harnessed to realize optical materials including "perfect lenses," [7] circular polarizers, [3] chiroptical sensors, [8] and negative refractive index materials. [9,10] In addition to these optical applications, chiral metallic nanostructures have been used for detection of biomolecular disease precursors, [11] chiral catalysis, [12] and chiral separations. [13] Many of the promising applications of chiral metallic nanostructures arise in part from their plasmonic chiroptical activity. At the nanoscale, individual metallic particles exhibit unique properties due to their high surface to volume ratio and geometric confinement of electrons. One particularly important property is the localized surface plasmon resonance (LSPR), [14] which occurs when the oscillation of surface electrons matches the frequency of incident photons. The spectral position and intensity of the LSPR depends not only on the size, shape, composition, and dielectric environment of the metallic nanoparticles (NPs) [15,16] but also on their aggregation state or assembly. [17] When metallic NPs are arranged in a chiral geometry, [18] the coupling of individual plasmons leads to collective plasmon oscillation across the entire structure. [19] Chiral NP assemblies may exhibit enhanced optical chirality in Chiral nanoparticle (NP) superstructures, in which discrete NPs are assembled into chiral architectures, represent an exciting and growing class of nanomaterials. Their enantiospecific properties make them promising candidates for a variety of potential applications. Helical NP superstructures are a rapidly expanding subclass of chiral nanomaterials in which NPs are arranged in three dimensions about a screw axis. Their intrinsic asymmetry gives rise to a variety of interesting properties, including plasmonic chir...
“…Peptides can also be designed to assemble and coil around nanomaterial templates and present nucleation sites for the growth of inorganic NPs. Kang et al designed a composite material consisting of a carbon nanotube (CNT) surrounded by an engineered peptide . The peptide sequence was designed to assemble into helices, where one face had an affinity for the CNTs and the other would bind the inorganic NPs.…”
Section: Helical Nanoparticle Superstructures: Methods Of Constructionmentioning
Chiral objects are defined as nonsuperimposable conformations that are mirror images of each other, much like a pair of left and right hands. In fact, the word "chiral" derives from the Greek word "χειρ" (kheir), which translates to "hand." Most biomolecules exist in only one particular conformation. For example, amino acids within large protein and peptide molecules are exclusively in the l-form (left-handed). It has long been considered that the phenomenon of homochirality (predominant occurrence of one conformation) could be linked to the origin of life. [1] These phenomena have inspired chemists and biologists to isolate, synthesize, and study the properties of chiral molecules. Research interest in chiral nanostructures has escalated rapidly since the early 2000s due to visionary reports that either predicted or demonstrated the potential applications of these materials. [2,3] In 2004, Pendry predicted that chiral metamaterials could be used to achieve negative refraction (Figure 1). [2] Following this seminal work, others demonstrated that such materials lead to circular dichroism (CD), [4] negative phase velocities, [5] and intense gyrotropy, [6] generating significant excitement within this emerging field. These properties can be harnessed to realize optical materials including "perfect lenses," [7] circular polarizers, [3] chiroptical sensors, [8] and negative refractive index materials. [9,10] In addition to these optical applications, chiral metallic nanostructures have been used for detection of biomolecular disease precursors, [11] chiral catalysis, [12] and chiral separations. [13] Many of the promising applications of chiral metallic nanostructures arise in part from their plasmonic chiroptical activity. At the nanoscale, individual metallic particles exhibit unique properties due to their high surface to volume ratio and geometric confinement of electrons. One particularly important property is the localized surface plasmon resonance (LSPR), [14] which occurs when the oscillation of surface electrons matches the frequency of incident photons. The spectral position and intensity of the LSPR depends not only on the size, shape, composition, and dielectric environment of the metallic nanoparticles (NPs) [15,16] but also on their aggregation state or assembly. [17] When metallic NPs are arranged in a chiral geometry, [18] the coupling of individual plasmons leads to collective plasmon oscillation across the entire structure. [19] Chiral NP assemblies may exhibit enhanced optical chirality in Chiral nanoparticle (NP) superstructures, in which discrete NPs are assembled into chiral architectures, represent an exciting and growing class of nanomaterials. Their enantiospecific properties make them promising candidates for a variety of potential applications. Helical NP superstructures are a rapidly expanding subclass of chiral nanomaterials in which NPs are arranged in three dimensions about a screw axis. Their intrinsic asymmetry gives rise to a variety of interesting properties, including plasmonic chir...
“…RM1 binds iron to form a stable, redox-active four-cysteine thiolate iron site that is structurally and functionally analogous to that of rubredoxin (Nanda et al ., 2005). Recently, Nanda, Fialkowski, and coworkers have been able to design ambidoxin, a 12-residue peptide with alternating D- and L-amino acid residues to stabilize a functional 4Fe–4S cubane cluster through metal–side chain interactions and an intricate network of hydrogen bonds (Kang et al ., 2018). Fig.…”
Section: Computational Design Guided By Fundamental Physicochemical Pmentioning
Proteins are molecular machines whose function depends on their ability to achieve complex folds with precisely defined structural and dynamic properties. The rational design of proteins from first-principles, or de novo, was once considered to be impossible, but today proteins with a variety of folds and functions have been realized. We review the evolution of the field from its earliest days, placing particular emphasis on how this endeavor has illuminated our understanding of the principles underlying the folding and function of natural proteins, and is informing the design of macromolecules with unprecedented structures and properties. An initial set of milestones in de novo protein design focused on the construction of sequences that folded in water and membranes to adopt folded conformations. The first proteins were designed from first-principles using very simple physical models. As computers became more powerful, the use of the rotamer approximation allowed one to discover amino acid sequences that stabilize the desired fold. As the crystallographic database of protein structures expanded in subsequent years, it became possible to construct proteins by assembling short backbone fragments that frequently recur in Nature. The second set of milestones in de novo design involves the discovery of complex functions. Proteins have been designed to bind a variety of metals, porphyrins, and other cofactors. The design of proteins that catalyze hydrolysis and oxygen-dependent reactions has progressed significantly. However, de novo design of catalysts for energetically demanding reactions, or even proteins that bind with high affinity and specificity to highly functionalized complex polar molecules remains an importnant challenge that is now being achieved. Finally, the protein design contributed significantly to our understanding of membrane protein folding and transport of ions across membranes. The area of membrane protein design, or more generally of biomimetic polymers that function in mixed or non-aqueous environments, is now becoming increasingly possible.
“…Peptides are well known for their excellent biomimetic properties as templates for the controlled growth of different NPs [68–70] . Peptides are composed of short chains of amino acids, which provide chemical diversity such as −COOH, −SH, −OH and −NH 2 groups.…”
Section: Bio‐templates For the Synthesis Of Mnmsmentioning
confidence: 99%
“…In the case of peptide‐derived synthesis, the peptide drives the nucleation process at a site where the nanoparticle growth starts and is then captured by the template, providing monodisperse size distribution and particle stability in the colloid solution [41] . In this regard, the stability is due to the strong affinity of the amino acid residues for metals [69] …”
Section: Bio‐templates For the Synthesis Of Mnmsmentioning
confidence: 99%
“…Using the chemical reduction method, Kang et al [69] . employed a programmed HexCoil‐Ala (HC) peptide to construct a superstructure of AuPt NPs on single‐wall carbon nanotubes (SWNTs) with tailored electrocatalytic activity (Figure 1).…”
Section: Bio‐templates For the Synthesis Of Mnmsmentioning
Developing metallic nanocatalysts with high reaction activity, selectivity and practical durability is a promising and active subfield in electrocatalysis. In the classical “bottom‐up” approach to synthesize stable nanomaterials by chemical reduction, stabilizing additives such as polymers or organic surfactants must be present to cap the nanoparticle to prevent material bulk aggregation. In recent years, biological systems have emerged as green alternatives to support the uncoated inorganic components. One key advantage of biological templates is their inherent ability to produce nanostructures with controllable composition, facet, size and morphology under ecologically friendly synthetic conditions, which are difficult to achieve with traditional inorganic synthesis. In addition, through genetic engineering or bioconjugation, bio‐templates can provide numerous possibilities for surface functionalization to incorporate specific binding sites for the target metals. Therefore, in bio‐templated systems, the electrocatalytic performance of the formed nanocatalyst can be tuned by precisely controlling the material surface chemistry. With controlled improvements in size, morphology, facet exposure, surface area and electron conductivity, bio‐inspired nanomaterials often exhibit enhanced catalytic activity towards electrode reactions. In this Review, recent research developments are presented in bio‐approaches for metallic nanomaterial synthesis and their applications in electrocatalysis for sustainable energy storage and conversion systems.
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