FIGURE 1 - uploaded by Robert I Maccuspie
Content may be subject to copyright.
Source publication
The peptide nano-rings containing Au nanoparticles inside their cavities were self-assembled on dithiol SAMs patterned as an array by AFM-based nanolithography. The peptide nano-rings were aligned as a line on these SAMs, and Au formed lines with the spacing between these nanoparticles as the peptide nano-rings functioned as spacers. This type of a...
Contexts in source publication
Context 1
... reduction of Au ions trapped inside the cavities of nano-rings, the peptide nano-rings could template Au nanoparticles. In this report, after Au nanoparticles were grown inside the cavities of the peptide nano-rings, these nano-rings containing Au nanoparticles were aligned on the chemically functionalized arrays patterned by nano-lithography (Fig. 1). Since these peptide nano-rings were self-assembled in a closely packed manner along the array of those dithiolated self-assembled monolayers (SAMs), these Au nanoparticles were positioned in the equal spacing on each line without touching each other as the peptide nano-rings functioned as spacers. This type of alignment of ...
Context 2
... the peptide nano-rings were previously synthesized, they were observed to be stable in solution [34] however these nano-rings have not been assembled on surfaces. Therefore, it was necessary to examine their stability via the simple surface-assembly. Before fabricating the structure shown in Fig. 1, we examined whether the Au nanoparticle-containing peptide nano-rings are rigid enough to be self-assembled on surfaces by spin-coating them on TEM grids. A height image of AFM in Fig. 2b confirms that the nano-rings were deposited on a TEM grid. This figure imaged the assembly of the nano-rings on the surface, but the Au ...
Context 3
... Then, mercaptohexadecanoic acid was assembled on the curved array where Au surfaces were exposed. The carboxylic groups on the top of these SAMs on trenches were substituted by thiol groups, as shown in Scheme 1. To align the peptide nano-rings containing Au nanoparticles on the dithiol SAM array patterned on a Au substrate as shown in Fig. 1, these nano-rings were incubated with this substrate in solution for 8 h. Because the end groups of the SAMs on the trenches were functionalized by thiol (Scheme 1), this incubation process allowed the nano-rings to selfassemble onto these trenches with the thiol-Au interaction, as shown in Fig. 3. Figure 3a is the AFM image of the ...
Context 4
... 3b since the brighter spheres in this phase image are more likely Au nanoparticles due to their surface hardness as compared to the one for the peptide nanorings. While these AFM images in the phase mode in low resolution do not explicitly show the discrete positioning of Au nanoparticles inside the nano-rings aligned on the trenches as shown in Fig. 1, the high-resolution image of the single trench containing the peptide nanorings in the phase mode assisted visualizing the peptide nano-ring alignment more clearly. When the single trench was imaged with the height mode image in high-resolution (Fig. 3c), still only continuous packing of the nano-rings was observable as a line along ...
Context 5
... alignment of Au nanoparticles was observed, as shown in Fig. 3d. In this high-resolution image, the harder Au nanoparticles appeared to be brighter and the spacing between these nanoparticles was visible. The most of Au nanoparticles in Fig. 3d were self-assembled discretely without touching each other due to the spacing of the peptide nano-rings (Fig. 1). The darker nano-ring contrast around the Au nanoparticle, observed in the spin-coated sample in Fig. 2b, was not observed clearly in Fig. 3d, however this phase contrast difference between the spin-coated nano-rings and the selfassembled nano-rings may be caused by their topological difference. For the spin-coated sample the ...
Context 6
... reduction of Au ions trapped inside the cavities of nano-rings, the peptide nano-rings could template Au nanoparticles. In this report, after Au nanoparticles were grown inside the cavities of the peptide nano-rings, these nano-rings containing Au nanoparticles were aligned on the chemically functionalized arrays patterned by nano-lithography (Fig. 1). Since these peptide nano-rings were self-assembled in a closely packed manner along the array of those dithiolated self-assembled monolayers (SAMs), these Au nanoparticles were positioned in the equal spacing on each line without touching each other as the peptide nano-rings functioned as spacers. This type of alignment of ...
Context 7
... the peptide nano-rings were previously synthesized, they were observed to be stable in solution [34] however these nano-rings have not been assembled on surfaces. Therefore, it was necessary to examine their stability via the simple surface-assembly. Before fabricating the structure shown in Fig. 1, we examined whether the Au nanoparticle-containing peptide nano-rings are rigid enough to be self-assembled on surfaces by spin-coating them on TEM grids. A height image of AFM in Fig. 2b confirms that the nano-rings were deposited on a TEM grid. This figure imaged the assembly of the nano-rings on the surface, but the Au ...
Context 8
... Then, mercaptohexadecanoic acid was assembled on the curved array where Au surfaces were exposed. The carboxylic groups on the top of these SAMs on trenches were substituted by thiol groups, as shown in Scheme 1. To align the peptide nano-rings containing Au nanoparticles on the dithiol SAM array patterned on a Au substrate as shown in Fig. 1, these nano-rings were incubated with this substrate in solution for 8 h. Because the end groups of the SAMs on the trenches were functionalized by thiol (Scheme 1), this incubation process allowed the nano-rings to selfassemble onto these trenches with the thiol-Au interaction, as shown in Fig. 3. Figure 3a is the AFM image of the ...
Context 9
... 3b since the brighter spheres in this phase image are more likely Au nanoparticles due to their surface hardness as compared to the one for the peptide nanorings. While these AFM images in the phase mode in low resolution do not explicitly show the discrete positioning of Au nanoparticles inside the nano-rings aligned on the trenches as shown in Fig. 1, the high-resolution image of the single trench containing the peptide nanorings in the phase mode assisted visualizing the peptide nano-ring alignment more clearly. When the single trench was imaged with the height mode image in high-resolution (Fig. 3c), still only continuous packing of the nano-rings was observable as a line along ...
Context 10
... alignment of Au nanoparticles was observed, as shown in Fig. 3d. In this high-resolution image, the harder Au nanoparticles appeared to be brighter and the spacing between these nanoparticles was visible. The most of Au nanoparticles in Fig. 3d were self-assembled discretely without touching each other due to the spacing of the peptide nano-rings (Fig. 1). The darker nano-ring contrast around the Au nanoparticle, observed in the spin-coated sample in Fig. 2b, was not observed clearly in Fig. 3d, however this phase contrast difference between the spin-coated nano-rings and the selfassembled nano-rings may be caused by their topological difference. For the spin-coated sample the ...
Similar publications
In this study, mercerization processes were performed on cotton fabrics with three different weaving patterns in chain mercerizer at 60°C by applying three different time periods and three different processes under factory conditions. The fabrics, which were weaved from 20/1 open-end and 100% cotton yarns, were used in the tests. The fabrics used i...
For the first time a full-color display processed by direct photo-lithography is demonstrated. The solution-processed devices consist of stripes of red, green and blue emitting polymers which are sandwiched between electrodes in a passive-matrix geometry. In contrast to other approaches the photo-activated crosslinking-reaction used to pattern the...
The aim of this study was to develop three-dimensional (3D) fully interlaced representative circular woven preform structures and to understand the effects of weave pattern and number of layers on 3D circular woven structures. Various 3D circular woven preforms were developed. Data generated from these structures included yarn-to-yarn space, densit...
Citations
... Nanorings are nanoscale circular bands, characterized by varying diameters and thicknesses. Nanorings have been synthesized using both physical (Nuraje et al., 2006;Wu et al., 2016) and chemical synthesis routes Jiang et al., 2004;Kelf et al., 2011;Nuraje et al., 2006). In the chemical realm, Hu et al. used the GRR between silver nanoplates and aqueous HAuCl 4 to form Ag-Au nanorings which were used as colorimetric nanosensors . ...
... Nanorings are nanoscale circular bands, characterized by varying diameters and thicknesses. Nanorings have been synthesized using both physical (Nuraje et al., 2006;Wu et al., 2016) and chemical synthesis routes Jiang et al., 2004;Kelf et al., 2011;Nuraje et al., 2006). In the chemical realm, Hu et al. used the GRR between silver nanoplates and aqueous HAuCl 4 to form Ag-Au nanorings which were used as colorimetric nanosensors . ...
Complex metal nanostructures represent an exceptional category of materials characterized by distinct morphologies and physicochemical properties. Nanostructures with shape anisotropies, such as nanorods, nanostars, nanocages, and nanoprisms, are particularly appealing due to their tunable surface plasmon resonances, controllable surface chemistries, and effective targeting capabilities. These complex nanostructures can absorb light in the near‐infrared, enabling noteworthy applications in nanomedicine, molecular imaging, and biology. The engineering of targeting abilities through surface modifications involving ligands, antibodies, peptides, and other agents potentiates their effects. Recent years have witnessed the development of innovative structures with diverse compositions, expanding their applications in biomedicine. These applications encompass targeted imaging, surface‐enhanced Raman spectroscopy, near‐infrared II imaging, catalytic therapy, photothermal therapy, and cancer treatment. This review seeks to provide the nanomedicine community with a thorough and informative overview of the evolving landscape of complex metal nanoparticle research, with a specific emphasis on their roles in imaging, cancer therapy, infectious diseases, and biofilm treatment.
This article is categorized under: Diagnostic Tools > In Vivo Nanodiagnostics and Imaging
Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease
Diagnostic Tools > Diagnostic Nanodevices
... In an alternative approach [99], Au NPs were precipitated from AuPMe 3 Cl (Me = methyl) in Au-peptide rings which self-assembled on a lithographically patterned substrate. The outer ring diameter was 50 nm and the inner (NP) diameter was 15 nm (r∼7.5 nm, s∼17.5 nm) which are too large, but the principle of defining the structure by the dimensions of an organic ring, e.g. ...
The structure and basic experimental electrical properties of vacuum evaporated discontinuous (island) metal thin films of discrete metal nanoparticles on insulating substrates are briefly reviewed. Then the widely accepted Neugebauer and Webb (N&W) electrostatically activated electron tunneling conduction model is covered (with enhancements) before the numerous discrepancies between this model and experimental observations are identified, e.g. minimal substrate bias effect, non-linear field distribution, anomalous AC effects, asymmetrical contact effects, and switching. A modified model, based on contact electron injection and extraction, and computer simulations are introduced which explain these discrepancies at a qualitative level. However, quantitative experimental verification of the model is not possible without stable, reproducible films of known structures. The paper concludes with a review of possible preparation techniques which could yield satisfactory samples, especially self-assembly of organically protected metal nanoparticles. One of these has already demonstrated electrostatically activated conduction.
... Since the successful development of dendrimerencapsulated NPs by Tomalia 43 and Crooks,44;45 dendrimers, as a class of nanomaterials, have been widely utilized in nanotechnology. 46 The subsequent development of dendrimerbased nano-composites [47][48][49][50][51][52][53][54][55][56][57][58][59][60][61] and nano-conjugates [62][63][64][65][66][67][68][69][70][71][72][73][74][75][76][77][78] is attractive because of their unique structures and properties, as well as their highly controllable internal and/or external functionalities and dimensions. ...
We report the synthesis and evaluation of four Newkome-type dendrons, G1-COOH, G2-COOH, SH-G1-COOH, and TA-G1-COOH, and their respective gold-dendron conjugates, where GX represents the generation number. G1- and G2-COOH are 2-directional symmetric dendrons that have cystamine cores containing a disulfide group. SH-G1-COOH was prepared by treatment of G1-COOH with dithioerythritol to yield a free thiol group to replace the disulfide linkage. TA-G1-COOH has a thioctic acid moiety, which is a 5-member ring containing a disulfide group that cleaves to produce two anchoring thiols to bond with the gold surface. All dendrons have peripheral carboxylate groups to afford hydrophilicity and functionality. Gold nanoparticle conjugates were prepared by reaction of each dendron solution with a suspension of gold colloid (nominally 10 nm diameter) and purified by stirred cell ultrafiltration. Chemical structures were confirmed by (1)H and (13)C nuclear magnetic resonance spectroscopy and matrix assisted laser desorption/ionization time-of-flight mass spectrometry. Particle size and surface plasmon resonance of the conjugates were characterized by dynamic light scattering (DLS) and UV-Vis spectroscopy, respectively. X-ray photoelectron spectroscopy (XPS) was utilized to confirm covalent bonding between the thiols on the dendron and the gold surface. XPS also revealed changes in the S/Au intensity ratio as a function of the dendron chemical structure, suggesting steric effects play a role in the reaction and/or conformation of dendrons on the gold surface. The colloidal and chemical stability of the conjugates as a function of temperature, pH, and suspending medium, and with respect to chemical resistance toward KCN, was investigated using DLS and UV-Vis absorption.
... It has been reported that noble metal NPs stabilized by only weakly bound ligands, such as citrate, will dynamically sorb and desorb proteins stochastically as the biological matrix they are exposed to changes (Cedervall et al. 2007b; Lundqvist et al. 2008; Lynch Tsai et al. 2010). It is also known that the corona of molecules encapsulating either inorganic (MacCuspie et al. 2010b; Voevodin et al. 2007) or biological (Banerjee et al. 2004; MacCuspie et al. 2008a, b; Nuraje et al. 2004 Nuraje et al. , 2006) NPs will affect their physical and biological properties. Thus, to probe the role of AgNP surface capping agents, three biocompatible capping agents were used on AgNPs surfaces including citrate, bovine serum albumin (BSA), and starch. ...
Understanding the colloidal stability of nanoparticles (NPs) plays a key role in phenomenological interpretation of toxicological
experiments, particularly if single NPs or their aggregates or agglomerates determine the dominant experimental result. This
report examines a variety of instrumental techniques for surveying the colloidal stability of aqueous suspensions of silver
nanoparticles (AgNPs), including atomic force microscopy, dynamic light scattering, and colorimetry. It was found that colorimetry
can adequately determine the concentration of single AgNPs that remained in solution if morphological information about agglomerates
is not required. The colloidal stability of AgNPs with various surface capping agents and in various solvents ranging from
cell culture media to different electrolytes of several concentrations, and in different pH conditions was determined. It
was found that biocompatible bulky capping agents, such as bovine serum albumin or starch, that provided steric colloidal
stabilization, as opposed to purely electrostatic stabilization such as with citrate AgNPs, provided better retention of single
AgNPs in solution over a variety of conditions for up to 64h of observation.
KeywordsSilver nanoparticles–BSA-coated nanoparticles–Nanomaterial dispersion protocol–Nanomaterial characterization
Bolaamphiphilic molecules with tyrosyl end groups formed interior-filled spherical self-assemblies, which are distinct from the vesicular or tubular structures of other similar peptidic bolaamphiphile assemblies reported in the literature. In this study, the self-assembly mechanism of these tyrosyl bolaamphiphiles was investigated taking into consideration the solvent effects on the molecular interaction forces using molecular modeling. The dissipative particle dynamics simulation of an aqueous tyrosyl bolaamphiphile solution suggested that the interior-filled assemblies were produced by a solvent-regulated assembly of small aggregates of bolaamphiphiles. These small aggregates were generated by hydrophobic interactions at an early stage, and then further assembled to form large spherical assemblies through intermolecular forces, including hydrogen bonds between the intermediate aggregates. Additional experiments and density functional theory calculations based on solvent variations proved that smaller assembled structures could be obtained by disrupting the hydrogen bonds between the intermediates. The assembly mechanism of these peptidic bolaamphiphiles afforded a facile way to create condensed supramolecular structures with controlled sizes.
In this paper, we use molecular dynamics simulations to study the assembly of DNA-grafted nanoparticles to demonstrate specifically the effect of bidispersity in grafted DNA strand length on the thermodynamics and structure of nanoparticle assembly at varying number of grafted single-stranded DNA (ssDNA) strands and number of guanine/cytosine (G/C) bases per strand. At constant number of grafted ssDNA strands and G/C nucleotides per strand, as bidispersity in strand lengths increases, the number of nanoparticles that assemble as well as the number of neighbours per particle in the assembled cluster increases. When the number of G/C nucleotides per strand in short and long strands is equal, the long strands hybridise with the other long strands with higher frequency than the short strands hybridise with short/long strands. This dominance of the long strands leads to bidisperse systems having similar thermodynamics to that in corresponding systems with monodisperse long strands. Structurally, however, as a result of long-long, long-short and short-short strand hybridisation, bidispersity in DNA strand length leads to a broader inter-particle distance distribution within the assembled cluster than seen in systems with monodisperse short or monodisperse long strands. The effect of increasing the number of G/C bases per strand or increasing the number of grafted DNA strands on the thermodynamics of assembly is similar for bidisperse and monodisperse systems. The effect of increasing the number of grafted ssDNA strands on the structure of the assembled cluster is dependent on the extent of strand bidispersity because the presence of significantly shorter ssDNA strands among long ssDNA strands reduces the crowding among the strands at high grafting density. This relief in crowding leads to larger number of strands hybridised and as a result larger coordination number in the assembled cluster in systems with high bidispersity in strands than in corresponding monodisperse or low bidispersity systems.
Given the diverse scientific and technological applications of gold nanoparticles (Au NPs), understanding the impact of macromolecular additives on the distribution of size, shape, and composition is crucial to ensure reproducibility and lower production cost. In situ measurement of the evolution of these distributions challenges current techniques; however, it is critical for in-line manufacturing controls. Using mild Au(I) reduction by tert-butylamine-borane in toluene, the utility and limitations of SAXS, UV/Vis spectroscopy, and TEM are considered by comparing the mean nanoparticle size, size distribution, and relative number density. Individually, these techniques are insufficient to follow these parameters through the initial process of nucleation and growth; either providing insufficient information on the number of particles (UV/Vis), introducing artifacts (TEM), or not providing a unique solution for the shape of the distribution (SAXS). However, when used in conjunction, especially SAXS calibrated with TEM of reaction aliquots, the time evolution of these parameters can be quantified. For the single-phase Au NP synthesis with Au(I) and mild reductants, four distinct experimental regions are revealed that entail two growth mechanisms, which complement previous discussions of single-mode growth kinetics. The kinetics of Au(I):borane reactions are dependent on the Au precursor/reductant ratio and the thiol capping agent length, when reductant concentration is low. The final reaction products exhibit an LSW size distribution.
In this review, the main concept of ferroelectricity of perovskite oxides and related materials at nanometer scale and existing difficulties in the synthesis of those nanocrystals are discussed. Important effects, such as depolarization field and size effect, on the existence of ferroelectricity in perovskite nanocrystals are deliberated. In the discussion of modeling works, different theoretical calculations are pinpointed focusing on their studies of lattice dynamics, phase transitions, new origin of ferroelectricity in nanostructures, etc. As the major part of this review, recent research progress in the facile synthesis, characterization and various applications of perovskite ferroelectric nanomaterials, such as BaTiO3, PbTiO3, PbZrO3, and BiFeO3, are also scrutinized. Perspectives concerning the future direction of ferroelectric nanomaterials research and its potential applications in renewable energy, etc., are presented. This review provides an overview in this area and guidance for further studies in perovskite ferroelectric nanomaterials and their applications.
Macroscopic assemblies of nanoparticles with fluid like characteristics, i.e. nanoparticle liquids (NPLs), are a new class of materials that exhibit unique properties compared with dispersions of nanoparticles in a molecularly distinct matrix phase. By focusing on reaction ratios, techniques to maximize concentration of reactants and quantification of chemical content during washing steps, a high degree of control over the purity of NPLs was maintained while allowing for easy scalability in batch sizes and synthesis throughput. A range of tertiary amines and quaternary ammoniums were used to successfully synthesize Au NPLs from a range of Au nanoparticles with nominal diameters from 6 to 20 nm and initially stabilized with either citrate or dodecanethiol. Stable Au NPLs after purification exhibited a sub-equivalence ratio of canopy to ligand molecules within the corona. This small canopy density most likely arose from the incommensurate areal density of anionic charge within the ligand shell relative to the larger size of the cationic canopy molecule, resulting in a population of cation–anion pairs too weakly bound to be retained in the initial assembly of the canopy post-purification. Finally, increasing either the volume fraction or molecular weight of the canopy was found to increase exponentially the electrical resistance of the bulk NPLs. Removal of excess canopy molecules created a conductive Au NPL that improved hot-current switching durability by at least two orders of magnitude beyond prior reports. Published in 2010 by John Wiley & Sons, Ltd.
