Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Evaporation-induced intercalation of nanosheets of organosilica, organoclay or various organic polymers within the interlayer spaces of an oriented bacteriorhodopsin/lipid membrane mesolamellar film is used to prepare stable, self-supporting biofunctional hybrid nanocomposites with photochromic and photoelectric properties. Compared with unmodified purple membrane films, mesolamellar nanocomposites containing intercalated organosilica exhibit enhanced stability in their photoelectric response at high relative humidity.

Mineralization of small-molecule-based supramolecular hydrogels with calcium phosphate produces hybrid composites comprising interconnecting networks of calcified nanofilaments (see figure). Viscoelastic hybrid gels that exhibit enhanced thermal stability, stiffness, and critical strain are formed at low mineral contents, whereas extensive mineralization generates hard macroporous replicas of the supramolecular matrix.

Two contrasting approaches, involving either polymer-mediated or fluoride-mediated self-transformation of amorphous solid particles, are described as general routes to the fabrication of hollow inorganic microspheres. Firstly, calcium carbonate and strontium tungstate hollow microspheres are fabricated in high yield using sodium poly(4-styrenesulfonate) as a stabilizing agent for the formation and subsequent transformation of amorphous primary particles. Transformation occurs with retention of the bulk morphology by localized Ostwald ripening, in which preferential dissolution of the particle interior is coupled to the deposition of a porous external shell of loosely packed nanocrystals. Secondly, the fabrication process is extended to relatively stable amorphous microspheres, such as TiO₂ and SnO₂, by increasing the surface reactivity of the solid precursor particles. For this, fluoride ions, in the form of NH₄F and SnF₂, are used to produce well-defined hollow spheroids of nanocrystalline TiO₂ and SnO₂, respectively. Our results suggest that the chemical self-transformation of precursor objects under morphologically invariant conditions could be of general applicability in the preparation of a wide range of nanoparticle-based hollow architectures for technological and biomedical applications.

Short chains and complex networks of interconnected Au nanoparticle chains (see Figure) are produced by a simple template-free approach. Optical spectroscopy and computer simulations show that surface plasmons from individual non-contacting nanoparticles are strongly coupled in the resulting 1D superstructures. These chains may provide a unique way to fabricate complex subwavelength optical waveguides.

Short, single-particle-wide chains and complex networks of interconnected chains are easily self-assembled from 13 nm Au nanoparticles by inducing a surface electrostatic dipolar moment in a controlled manner. Mann and co-workers further demonstrate both experimentally and theoretically on p. 2553 that efficient surface plasmon coupling takes place in these extensive networks, thus opening a new bottom–up approach to subwavelength optical-waveguiding devices. The left panel in the image shows isolated 13 nm Au nanoparticles; the back panel, short linear chains; the bottom panel, complex branched network of chains; and the right panel, a graphical rendering of optical spectroscopic properties during the self-assembly process.

Although molecule-based materials can combine physical and chemical properties associated with molecular-scale building blocks, their successful integration into real applications depends also on higher-order properties, such as crystal size, shape, and organization. New approaches involving templating and self- or facilitated assembly of nanoscale building blocks to prepare novel multifunctional molecular magnetic materials with complex form and organization are described.

A novel process for wrapping individual myoglobin molecules with an ultrathin shell of silica is reported. Confinement of single protein molecules in microemulsion water droplets followed by the controlled hydrolysis and condensation of tetramethoxysilane at the oil/water interface produces discrete protein/ silica nanoparticles (see Figure) without loss of myoglobin structure and function.

Templatgestützte Prozesse unter Beteiligung von Polysaccharid, Dextran und Zeolithkristallen oder -nanopartikeln dienen zum Aufbau eines ausgefeilten porösen Gerüsts aus verknüpften Filamenten aus NaY-Zeolith/Silicat-Nanopartikeln sowie makroskopischen Fasern aus kristallographisch ausgerichteten Silicalitnanokristallen (siehe Bild; Balkenlänge: 5 μm).

Schön verpackt: Biomoleküle können in die ultradünne Schale eines Aminopropyl-funktionalisierten Magnesium(organo)phyllosilicats eingehüllt werden und ergeben so wässrige Dispersionen einzelner Nanopartikel aus Protein- und anorganischem Material (A). Ähnliche Methoden führen mithilfe von Tonerde-Oligomeren mit langkettigen, hydrophoben organischen Resten zur Selbstorganisation dieser Nanopartikel zu Überstrukturen höherer Ordnung (B).

Die geologische Langlebigkeit vonLingula (siehe Bild) spricht dafür, dass sich die leicht mineralisierte carbonatsubstituierte Fluorapatit(FAP)-Schale evolutionär gut angepasst hat. Entgegen früheren Untersuchungen wurde gezeigt, dass aus Lingula isolierte, lösliche Makromoleküle spezifisch die FAP-Kristallisation durch Destabilisierung einer amorphen Calciumphosphat-Vorstufe begünstigen.

Template-directed processes involving polysaccharide, dextran, and preformed zeolite crystals/nanoparticles are used to prepare elaborate porous frameworks of interconnected filaments of NaY zeolite/silica nanoparticles, as well as macroscopic fibers of crystallographically aligned silicalite nanocrystals (see picture; bar is 5 μm).

The geological longevity ofLingula, depicted, suggests that the lightly mineralized carbonate-substituted fluorapatite (FAP) shell has remained well-adapted to evolutionary pressures. Contrary to earlier studies, soluble macromolecules isolated from Lingula shells are shown to specifically promote FAP crystallization by the destabilization of an amorphous calcium phosphate precursor.

Gift wrapped: Biomolecules can be enveloped within an ultrathin shell of an aminopropyl-functionalized magnesium (organo)phyllosilicate to produce aqueous dispersions of discrete protein–inorganic nanoparticles. Similar procedures but with organoclay oligomers that have pendent long-chain hydrophobic moieties result in self-assembly of the protein–inorganic nanoparticles into higher-order superstructures (see picture).

Die Organisation von Nanostrukturen über mehrere Längenskalen ist eine Schlüsselherausforderung im Design von integrierten Materialien mit verbesserten Funktionen. Derzeitige Ansätze greifen bevorzugt auf physikalische Methoden wie Musterbildung zurück, und nicht auf Methoden wie spontane chemische Selbstorganisation und Umwandlung von Baueinheiten über mehrere Längenskalen. Es sollte möglich sein, eine Chemie der organisierten Materie zu entwickeln, die auf Prozessen beruht, in denen die Zeit- und Längenskalenkopplung wechselwirkender Komponenten übergeordnete Architekturen mit eingebetteter Struktur hervorbringt. In diesem Aufsatz zeigen wir, wie das Wechselspiel von Aggregation und Kristallisation die Selbstorganisation auf der Mesoskala, kooperative Umwandlung und Reorganisation von organisch-anorganischen Hybridbaueinheiten unter Bildung von Einkristallen mit Mosaikstruktur, Nanopartikelarrays und emergenten Nanostrukturen mit komplexer Form und Hierarchie auslösen kann. Wir schlagen vor, dass ähnliche Prozesse, die auf der Mesoskala wirksam sind, auch für Modelle der matrixvermittelten Keimbildung bei der Biomineralisation relevant sind.

The organization of nanostructures across extended length scales is a key challenge in the design of integrated materials with advanced functions. Current approaches tend to be based on physical methods, such as patterning, rather than the spontaneous chemical assembly and transformation of building blocks across multiple length scales. It should be possible to develop a chemistry of organized matter based on emergent processes in which time- and scale-dependent coupling of interactive components generate higher-order architectures with embedded structure. Herein we highlight how the interplay between aggregation and crystallization can give rise to mesoscale self-assembly and cooperative transformation and reorganization of hybrid inorganic–organic building blocks to produce single-crystal mosaics, nanoparticle arrays, and emergent nanostructures with complex form and hierarchy. We propose that similar mesoscale processes are also relevant to models of matrix-mediated nucleation in biomineralization.

Progress reports are a new type of article in Advanced Materials, dealing with the hottest current topics, and providing readers with a critically selected overview of important progress in these fields. It is not intended that the articles be comprehensive, but rather insightful, selective, critical, opinionated, and even visionary. We have approached scientists we believe are at the very forefront of these fields to contribute the articles, which will appear on an annual basis. The article below describes the latest advances in bio-inspired materials chemistry.

Progress reports are a new type of article in Advanced Engineering Materials, dealing with the hottest current topics, and providing readers with a critically selected overview of important progress in these fields. It is not intended that the articles be comprehensive, but rather insightful, selective, critical, opinionated, and even visionary. We have approached scientists we believe are at the very forefront of these fields to contribute the articles, which will appear on an annual basis. The article below describes the latest advances in Bio-inspired Materials Chemistry.

A lamellar hybrid mesostructure containing polymerizable diacetylinic groups is coassembled in the in situ synthesis of silica by acid hydrolysis and condensation of tetraethylorthosilicate (TEOS) in the presence of 1,2-bis(10,12-tricosadiyonyl)-sn-glycero-3-phosphatidylcholine (DC_8,9PC) lipid molecules. This mesostructure is subsequently twisted into high aspect-ratio tubules and ribbons with helical architecture (see picture). Interactions between the silica and lipid headgroups promote diacetylenic polymerization under conditions at which the unmineralized lipid microstructures show little or no activity.

Eine lamellare Hybrid-Mesostruktur mit polymerisierbaren Diacetylengruppen wird bei der In-situ-Synthese von Siliciumdioxid durch saure Hydrolyse und Kondensation von Tetraethylorthosilicat (TEOS) in Gegenwart von 1,2-Bis(10,12-tricosadiinonyl)-sn-glycero-3-phosphatidylcholin (DC_8,9PC) gebildet. Diese Mesostruktur lagert sich allmählich in helical gedrehte Röhren und Bänder mit einem großen Längen-zu-Breiten-Verhältnis um (siehe Bild). Wechselwirkungen zwischen dem Siliciumdioxid und den lipidischen Kopfgruppen fördern die Polymerisation der Endgruppen bei Bedingungen, unter denen nichtmineralisierte lipidische Mikrostrukturen nur wenig oder keine Aktivität zeigen.

BaSO₄ fibres with morphological complexity were formed in aqueous solution with polyacrylate and partially monophosphonated poly(ethyleneoxide)-block-poly(methacrylic acid) additives by a simple precipitation reaction. For polyacrylate, formation of the fibrous deposits was strongly dependent on the level of supersaturation (S) and Ba²⁺:polymer molar ratio (R). At S=60 to 80, and R=3 to 14, highly anisotropic crystalline fibres consisting of bundles of BaSO₄ nanofilaments were formed after several weeks, although the yield was low. The nanofilaments were also organized into cone-shaped aggregates at S=80, and at lower R values these formed higher-order structures that consisted of multiple cone-on-cone assemblies with remarkable self-similarity. Increasing the supersaturation produced ovoid or cross-shaped dendritic particles for the range of molar ratios studied. In contrast, BaSO₄ crystallisation in the presence of a partially phosphonated block copolymer gave a high yield of BaSO₄ fibres up to 100 μm in length, and consisting of co-aligned bundles of 30 nm-diameter defect-free single-crystal nanofilaments with a uniform growth tip. A model for the defect-free growth of BaSO₄ nanofilaments in aqueous polymer solutions based on amorphous precursor particles, vectorially directing forces and van der Waals attraction is proposed.