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2502 KiB

Open AccessArticle

In Situ Self Assembly of Nanocomposites: Competition of Chaotic Advection and Interfacial Effects as Observed by X-Ray Diffreaction

by Dilru R. Ratnaweera, Chaitra Mahesha, David A. Zumbrunnen and Dvora Perahia

Nanomaterials 2015, 5(1), 351-365; https://doi.org/10.3390/nano5010351 - 17 Mar 2015

Cited by 2 | Viewed by 5022

Abstract

The effects of chaotic advection on the in situ assembly of a hierarchal nanocomposite of Poly Amide 6, (nylon 6 or PA6) and platelet shape nanoparticles (NPs) were studied. The assemblies were formed by chaotic advection, where melts of pristine PA6 and a [...] Read more.

The effects of chaotic advection on the in situ assembly of a hierarchal nanocomposite of Poly Amide 6, (nylon 6 or PA6) and platelet shape nanoparticles (NPs) were studied. The assemblies were formed by chaotic advection, where melts of pristine PA6 and a mixture of PA6 with NPs were segregated into discrete layers and extruded into film in a continuous process. The process assembles the nanocomposite into alternating pristine-polymer and oriented NP/polymer layers. The structure of these hierarchal assemblies was probed by X-rays as a processing parameter, N, was varied. This parameter provides a measure of the extent of in situ structuring by chaotic advection. We found that all assemblies are semi-crystalline at room temperature. Increasing N impacts the ratio of α to γ crystalline forms. The effects of the chaotic advection vary with the concentration of the NPs. For nanocomposites with lower NP concentrations the amount of the γ crystalline form increased with N. However, at higher NP concentrations, interfacial effects of the NP play a significant role in determining the structure, where the NPs oriented along the melt flow direction and the polymer chains oriented perpendicular to the NP surfaces. Full article

(This article belongs to the Special Issue Self-Assembled Nanomaterials)

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1260 KiB

Open AccessArticle

Fungal Hydrophobin Proteins Produce Self-Assembling Protein Films with Diverse Structure and Chemical Stability

by Victor C. Lo, Qin Ren, Chi L. L. Pham, Vanessa K. Morris, Ann H. Kwan and Margaret Sunde

Nanomaterials 2014, 4(3), 827-843; https://doi.org/10.3390/nano4030827 - 17 Sep 2014

Cited by 45 | Viewed by 10542

Abstract

Hydrophobins are small proteins secreted by fungi and which spontaneously assemble into amphipathic layers at hydrophilic-hydrophobic interfaces. We have examined the self-assembly of the Class I hydrophobins EAS_∆15 and DewA, the Class II hydrophobin NC2 and an engineered chimeric hydrophobin. These Class [...] Read more.

Hydrophobins are small proteins secreted by fungi and which spontaneously assemble into amphipathic layers at hydrophilic-hydrophobic interfaces. We have examined the self-assembly of the Class I hydrophobins EAS_∆15 and DewA, the Class II hydrophobin NC2 and an engineered chimeric hydrophobin. These Class I hydrophobins form layers composed of laterally associated fibrils with an underlying amyloid structure. These two Class I hydrophobins, despite showing significant conformational differences in solution, self-assemble to form fibrillar layers with very similar structures and require a hydrophilic-hydrophobic interface to trigger self-assembly. Addition of additives that influence surface tension can be used to manipulate the fine structure of the protein films. The Class II hydrophobin NC2 forms a mesh-like protein network and the engineered chimeric hydrophobin displays two multimeric forms, depending on assembly conditions. When formed on a graphite surface, the fibrillar EAS_∆15 layers are resistant to alcohol, acid and basic washes. In contrast, the NC2 Class II monolayers are dissociated by alcohol treatment but are relatively stable towards acid and base washes. The engineered chimeric Class I/II hydrophobin shows increased stability towards alcohol and acid and base washes. Self-assembled hydrophobin films may have extensive applications in biotechnology where biocompatible; amphipathic coatings facilitate the functionalization of nanomaterials. Full article

(This article belongs to the Special Issue Self-Assembled Nanomaterials)

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476 KiB

Open AccessArticle

Inclusion of Zinc Oxide Nanoparticles into Virus-Like Peptide Nanocapsules Self-Assembled from Viral β-Annulus Peptide

by Seiya Fujita and Kazunori Matsuura

Nanomaterials 2014, 4(3), 778-791; https://doi.org/10.3390/nano4030778 - 02 Sep 2014

Cited by 25 | Viewed by 8458

Abstract

A viral β-annulus peptide connected with a zinc oxide (ZnO)-binding sequence (HCVAHR) at its N-terminal was synthesized, and the inclusion behavior of quantum-sized ZnO nanoparticles into the peptide nanocapsules formed by self-assembly of the peptide in water was investigated. Dynamic light scattering (DLS) [...] Read more.

A viral β-annulus peptide connected with a zinc oxide (ZnO)-binding sequence (HCVAHR) at its N-terminal was synthesized, and the inclusion behavior of quantum-sized ZnO nanoparticles into the peptide nanocapsules formed by self-assembly of the peptide in water was investigated. Dynamic light scattering (DLS) measurements showed that ZnO nanoparticles (approximately 10 nm) in the presence of the peptide (0.1 mM) formed assemblies with an average size of 48 ± 24 nm, whereas ZnO nanoparticles in the absence of the peptide formed large aggregates. Transmission electron microscopy (TEM) observations of the ZnO nanoparticles in the presence of the peptide revealed that ZnO nanoparticles were encapsulated into the peptide nanocapsules with a size of approximately 50 nm. Fluorescence spectra of a mixture of the peptide and ZnO nanoparticles suggested that the ZnO surface and the peptide interact. Template synthesis of ZnO nanoparticles with the peptide nanocapsules afforded larger nanoparticles (approximately 40 nm), which are not quantum-sized ZnO. Full article

(This article belongs to the Special Issue Self-Assembled Nanomaterials)

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2790 KiB

Open AccessArticle

Self-Assembling Organic Micro-/Nano-Pillars on Gold and Glass Surfaces

by Hai-Feng Ji, Wenli Ruan, Yingying Li and Guohua Ding

Nanomaterials 2014, 4(3), 768-777; https://doi.org/10.3390/nano4030768 - 02 Sep 2014

Cited by 4 | Viewed by 5297

Abstract

In this work, we report the formation of a family of organic micro-/nano-pillars prepared from surface-assisted self-assembly processes and factors controlling the growth of the pillars. These acids include cyanuric acid (CA), 1,3,5-benzenetricarboxylic acid (TMA), 1,2,4,5-benzenetetracarboxylic acid (TA) and 3,4,9,10-perylenetetracarboxylic acid (PTA). Aqueous [...] Read more.

In this work, we report the formation of a family of organic micro-/nano-pillars prepared from surface-assisted self-assembly processes and factors controlling the growth of the pillars. These acids include cyanuric acid (CA), 1,3,5-benzenetricarboxylic acid (TMA), 1,2,4,5-benzenetetracarboxylic acid (TA) and 3,4,9,10-perylenetetracarboxylic acid (PTA). Aqueous solutions mixed with acids and melamine (M) can be fine-tuned to prepare ordered micro-/nano-pillars on substrates, which can be further optimized for their applications Full article

(This article belongs to the Special Issue Self-Assembled Nanomaterials)

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1204 KiB

Open AccessArticle

The Use of the Calcitonin Minimal Recognition Module for the Design of DOPA-Containing Fibrillar Assemblies

by Galit Fichman, Tom Guterman, Lihi Adler-Abramovich and Ehud Gazit

Nanomaterials 2014, 4(3), 726-740; https://doi.org/10.3390/nano4030726 - 20 Aug 2014

Cited by 9 | Viewed by 7137

Abstract

Amyloid deposits are insoluble fibrous protein aggregates, identified in numerous diseases, which self-assemble through molecular recognition. This process is facilitated by short amino acid sequences, identified as minimal modules. Peptides corresponding to these motifs can be used for the formation of amyloid-like fibrillar [...] Read more.

Amyloid deposits are insoluble fibrous protein aggregates, identified in numerous diseases, which self-assemble through molecular recognition. This process is facilitated by short amino acid sequences, identified as minimal modules. Peptides corresponding to these motifs can be used for the formation of amyloid-like fibrillar assemblies in vitro. Such assemblies hold broad appeal in nanobiotechnology due to their ordered structure and to their ability to be functionalized. The catechol functional group, present in the non-coded L-3,4-dihydroxyphenylalanine (DOPA) amino acid, can take part in diverse chemical interactions. Moreover, DOPA-incorporated polymers have demonstrated adhesive properties and redox activity. In this work, amyloid-like fibrillar assemblies were formed through the self-assembly of a pentapeptide containing DOPA residues, Asp-DOPA-Asn-Lys-DOPA. The design of this peptide was based on the minimal amyloidogenic recognition motif of the human calcitonin hormone, Asp-Phe-Asn-Lys-Phe, the first amyloidogenic pentapeptide identified. By substituting phenylalanine with DOPA, we obtained DOPA-functionalized amyloid-like assemblies in water. Electron microscopy revealed elongated, linear fibril-like nanometric assemblies. Secondary structure analysis indicated the presence of amyloid-characteristic β-sheet structures as well as random coil structures. Deposition of silver on the DOPA-incorporated assemblies suggested redox activity and demonstrated the applicative potential of this novel nanobiomaterial. Full article

(This article belongs to the Special Issue Self-Assembled Nanomaterials)

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1852 KiB

Open AccessArticle

Design of Magnetic Gelatine/Silica Nanocomposites by Nanoemulsification: Encapsulation versus in Situ Growth of Iron Oxide Colloids

by Joachim Allouche, Corinne Chanéac, Roberta Brayner, Michel Boissière and Thibaud Coradin

Nanomaterials 2014, 4(3), 612-627; https://doi.org/10.3390/nano4030612 - 31 Jul 2014

Cited by 9 | Viewed by 9400

Abstract

The design of magnetic nanoparticles by incorporation of iron oxide colloids within gelatine/silica hybrid nanoparticles has been performed for the first time through a nanoemulsion route using the encapsulation of pre-formed magnetite nanocrystals and the in situ precipitation of ferrous/ferric ions. The first [...] Read more.

The design of magnetic nanoparticles by incorporation of iron oxide colloids within gelatine/silica hybrid nanoparticles has been performed for the first time through a nanoemulsion route using the encapsulation of pre-formed magnetite nanocrystals and the in situ precipitation of ferrous/ferric ions. The first method leads to bi-continuous hybrid nanocomposites containing a limited amount of well-dispersed magnetite colloids. In contrast, the second approach allows the formation of gelatine-silica core-shell nanostructures incorporating larger amounts of agglomerated iron oxide colloids. Both magnetic nanocomposites exhibit similar superparamagnetic behaviors. Whereas nanocomposites obtained via an in situ approach show a strong tendency to aggregate in solution, the encapsulation route allows further surface modification of the magnetic nanocomposites, leading to quaternary gold/iron oxide/silica/gelatine nanoparticles. Hence, such a first-time rational combination of nano-emulsion, nanocrystallization and sol-gel chemistry allows the elaboration of multi-component functional nanomaterials. This constitutes a step forward in the design of more complex bio-nanoplatforms. Full article

(This article belongs to the Special Issue Self-Assembled Nanomaterials)

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690 KiB

Open AccessArticle

Directed Kinetic Self-Assembly of Mounds on Patterned GaAs (001): Tunable Arrangement, Pattern Amplification and Self-Limiting Growth

by Chuan-Fu Lin, Hung-Chih Kan, Subramaniam Kanakaraju, Christopher Richardson and Raymond Phaneuf

Nanomaterials 2014, 4(2), 344-354; https://doi.org/10.3390/nano4020344 - 12 May 2014

Cited by 2 | Viewed by 5841

Abstract

We present results demonstrating directed self-assembly of nanometer-scale mounds during molecular beam epitaxial growth on patterned GaAs (001) surfaces. The mound arrangement is tunable via the growth temperature, with an inverse spacing or spatial frequency which can exceed that of the features of [...] Read more.

We present results demonstrating directed self-assembly of nanometer-scale mounds during molecular beam epitaxial growth on patterned GaAs (001) surfaces. The mound arrangement is tunable via the growth temperature, with an inverse spacing or spatial frequency which can exceed that of the features of the template. We find that the range of film thickness over which particular mound arrangements persist is finite, due to an evolution of the shape of the mounds which causes their growth to self-limit. A difference in the film thickness at which mounds at different sites self-limit provides a means by which different arrangements can be produced. Full article

(This article belongs to the Special Issue Self-Assembled Nanomaterials)

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Review

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2873 KiB

Open AccessReview

Self-Assembly in Biosilicification and Biotemplated Silica Materials

by Francisco M. Fernandes, Thibaud Coradin and Carole Aimé

Nanomaterials 2014, 4(3), 792-812; https://doi.org/10.3390/nano4030792 - 04 Sep 2014

Cited by 36 | Viewed by 9653

Abstract

During evolution, living organisms have learned to design biomolecules exhibiting self-assembly properties to build-up materials with complex organizations. This is particularly evidenced by the delicate siliceous structures of diatoms and sponges. These structures have been considered as inspiration sources for the preparation of [...] Read more.

During evolution, living organisms have learned to design biomolecules exhibiting self-assembly properties to build-up materials with complex organizations. This is particularly evidenced by the delicate siliceous structures of diatoms and sponges. These structures have been considered as inspiration sources for the preparation of nanoscale and nanostructured silica-based materials templated by the self-assembled natural or biomimetic molecules. These templates range from short peptides to large viruses, leading to biohybrid objects with a wide variety of dimensions, shapes and organization. A more recent strategy based on the integration of biological self-assembly as the driving force of silica nanoparticles organization offers new perspectives to elaborate highly-tunable, biofunctional nanocomposites. Full article

(This article belongs to the Special Issue Self-Assembled Nanomaterials)

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1654 KiB

Open AccessReview

Nano-Assemblies of Modified Cyclodextrins and Their Complexes with Guest Molecules: Incorporation in Nanostructured Membranes and Amphiphile Nanoarchitectonics Design

by Leïla Zerkoune, Angelina Angelova and Sylviane Lesieur

Nanomaterials 2014, 4(3), 741-765; https://doi.org/10.3390/nano4030741 - 20 Aug 2014

Cited by 80 | Viewed by 12317

Abstract

A variety of cyclodextrin-based molecular structures, with substitutions of either primary or secondary faces of the natural oligosaccharide macrocycles of α-, β-, or γ-cyclodextrins, have been designed towards innovative applications of self-assembled cyclodextrin nanomaterials. Amphiphilic cyclodextrins have been obtained by chemical or enzymatic [...] Read more.

A variety of cyclodextrin-based molecular structures, with substitutions of either primary or secondary faces of the natural oligosaccharide macrocycles of α-, β-, or γ-cyclodextrins, have been designed towards innovative applications of self-assembled cyclodextrin nanomaterials. Amphiphilic cyclodextrins have been obtained by chemical or enzymatic modifications of their macrocycles using phospholipidyl, peptidolipidyl, cholesteryl, and oligo(ethylene oxide) anchors as well as variable numbers of grafted hydrophobic hydrocarbon or fluorinated chains. These novel compounds may self-assemble in an aqueous medium into different types of supramolecular nanoassemblies (vesicles, micelles, nanorods, nanospheres, and other kinds of nanoparticles and liquid crystalline structures). This review discusses the supramolecular nanoarchitectures, which can be formed by amphiphilic cyclodextrin derivatives in mixtures with other molecules (phospholipids, surfactants, and olygonucleotides). Biomedical applications are foreseen for nanoencapsulation of drug molecules in the hydrophobic interchain volumes and nanocavities of the amphiphilic cyclodextrins (serving as drug carriers or pharmaceutical excipients), anticancer phototherapy, gene delivery, as well as for protection of instable active ingredients through inclusion complexation in nanostructured media. Full article

(This article belongs to the Special Issue Self-Assembled Nanomaterials)

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