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Supramolecular fibers in water, micrometers long and several nanometers in width, are among the most studied nanostructures for biomedical applications. These supramolecular polymers are formed through a spontaneous self-assembly process of small amphiphilic molecules by specific secondary interactions. Although many compounds do not possess a stereocenter, recent studies suggest the (co)existence of helical structures, albeit in racemic form. Here, we disclose a series of supramolecular (co)polymers based on water-soluble benzene-1,3,5-tricarboxamides (BTAs) that form double helices, fibers that were long thought to be chains of single molecules stacked in one dimension (1D). Detailed cryogenic transmission electron microscopy (cryo-TEM) studies and subsequent three-dimensional-volume reconstructions unveiled helical repeats, ranging from 15 to 30 nm. Most remarkable, the pitch can be tuned through the composition of the copolymers, where two different monomers with the same core but different peripheries are mixed in various ratios. Like in lipid bilayers, the hydrophobic shielding in the aggregates of these disc-shaped molecules is proposed to be best obtained by dimer formation, promoting supramolecular double helices. It is anticipated that many of the supramolecular polymers in water will have a thermodynamic stable structure, such as a double helix, although small structural changes can yield single stacks as well. Hence, it is essential to perform detailed analyses prior to sketching a molecular picture of these 1D fibers.

Collagen type I is one of the major structural proteins in mammals, providing tissues such as cornea, tendon, bone, skin, and dentin with mechanical stability, strength, and toughness. Collagen fibrils are composed of collagen molecules arranged in a quarter-stagger array that gives rise to a periodicity of 67 nm along the fibril axis, with a 30 nm overlap zone and a 37 nm gap zone. The formation of such highly organized fibrils is a self-assembly process where electrostatic and hydrophobic interactions play a critical role in determining the staggering of the molecules with 67 nm periodicity. While collagen self-assembly has been extensively studied, not much is known about the mechanism, and in particular, the nature of the nuclei that initially form, the different stages of the aggregation process, and how the organization of the molecules into fibrils arises. By combining time-resolved cryo-transmission electron microscopy with molecular dynamics simulations, we show that collagen assembly is a multistep process in which the molecules first form filaments which self-organize into fibrils with a disordered structure. The appearance of the D-band periodicity is gradual and starts with the alignment of adjacent filaments at the N-terminal end of the molecules, first leading to bands with a periodicity of 67 nm and then to the formation of gap and overlap regions.

The nucleation of crystals has long been thought to occur through the stochastic association of ions, atoms or molecules to form critical nuclei, which will later grow out to crystals1. Only in the past decade has the awareness grown that crystallization can also proceed through the assembly of different types of building blocks2,3, including amorphous precursors4, primary particles5, prenucleation species6,7, dense liquid droplets8,9or nanocrystals10. However, the forces that control these alternative pathways are still poorly understood. Here, we investigate the crystallization of magnetite (Fe3O4) through the formation and aggregation of primary particles and show that both the thermodynamics and the kinetics of the process can be described in terms of colloidal assembly. This model allows predicting the average crystal size at a given initial Fe concentration, thereby opening the way to the design of crystals with predefined sizes and properties.

Classical molecular dynamics simulations and free energy methods have been used to obtain a better understanding of the molecular processes occurring prior to the first nucleation event for calcium phosphate biominerals. The association constants for the formation of negatively charged complexes containing calcium and phosphate ions in aqueous solution have been computed, and these results suggest that the previously proposed calcium phosphate building unit, [Ca(HPO4)3]4–, should only be present in small amounts under normal experimental conditions. However, the presence of an activation barrier for the removal of an HPO42–ion from this complex indicates that this species could be kinetically trapped. Aggregation pathways involving CaHPO4, [Ca(HPO4)2]2–, and [Ca(HPO4)3]4–complexes have been explored with the finding that dimerization is favorable up to a Ca/HPO4ratio of 1:2.

Magnetite (Fe3O4) nanoaggregates with a flower-like morphology are considered promising materials in the field of magnetically induced hyperthermia in cancer therapy due to their good heating efficiency at low applied alternating magnetic fields. Although the structure and the magnetic state of such flower-like aggregates have been investigated previously, the mechanism that leads to the hierarchical morphology is still poorly understood. Here, we study the formation mechanism of Fe3O4aggregates synthesized through the partial oxidation of ferrous hydroxide in the presence of poly(acrylic acid) by using cryogenic electron microscopy. The aggregates are formed through a multistep process involving first the conversion of ferrous hydroxide precursors in ∼5 nm primary particles that aggregate into ∼10 nm primary Fe3O4crystals that finally arrange into the secondary mesocrystal structure. High-resolution electron tomography is used to show that the Fe3O4mesocrystals are composed of ∼10 nm subunits, often showing a uniform crystallographic orientation resulting in single-crystal-like diffraction patterns. Furthermore, electron holography reveals that mesocrystals have a single magnetic domain despite polymeric interfaces between subunits being present throughout the mesocrystal. Our findings could be used to design materials with specific properties by modulating the morphology and/or magnetic state that is suitable for biomedical application.

The self-assembly of amphiphilic molecules in solution is a ubiquitous process in both natural and synthetic systems. The ability to effectively control the structure and properties of these systems is essential for tuning the quality of their functionality, yet the underlying mechanisms governing the transition from molecules to assemblies have not been fully resolved. Here we describe how amphiphilic self-assembly can be preceded by liquid–liquid phase separation. The assembly of a model block co-polymer system into vesicular structures was probed through a combination of liquid-phase electron microscopy, self-consistent field computations and Gibbs free energy calculations. This analysis shows the formation of polymer-rich liquid droplets that act as a precursor in the bottom-up formation of spherical micelles, which then evolve into vesicles. The liquid–liquid phase separation plays a role in determining the resulting vesicles’ structural properties, such as their size and membrane thickness, and the onset of kinetic traps during self-assembly.

In this study, native chemical ligation (NCL) was used as a selective cross-linking method to form core-cross-linked thermosensitive polymeric micelles for drug delivery applications. To this end, two complementary ABA triblock copolymers having polyethylene glycol (PEG) as midblock were synthesized by atom transfer radical polymerization (ATRP). The thermosensitive poly isopropylacrylamide (PNIPAM) outer blocks of the polymers were copolymerized with either N-(2-hydroxypropyl)methacrylamide-cysteine (HPMA-Cys), P(NIPAM-co-HPMA-Cys)-PEG-P(NIPAM-co-HPMA-Cys) (PNC) or N-(2-hydroxypropyl)methacrylamide-ethylthioglycolate succinic acid (HPMA-ETSA), P(NIPAM-co-HPMA-ETSA)-PEG-P(NIPAM-co-HPMA-ETSA) (PNE). Mixing of these polymers in aqueous solution followed by heating to 50 °C resulted in the formation of thermosensitive flower-like micelles. Subsequently, native chemical ligation in the core of micelles resulted in stabilization of the micelles with a Z-average of 65 nm at body temperature. Decreasing the temperature to 10 °C only affected the size of the micelles (increased to 90 nm) but hardly affected the polydispersity index (PDI) and aggregation number (Nagg) confirming covalent stabilization of the micelles by NCL. CryoTEM images showed micelles with an uniform spherical shape and dark patches close to the corona of micelles were observed in the tomographic view. The dark patches represent more dense areas in the micelles which coincide with the higher content of HPMA-Cys/ETSA close to the PEG chain revealed by the polymerization kinetics study. Notably, this cross-linking method provides the possibility for conjugation of functional molecules either by using the thiol moieties still present after NCL or by simply adjusting the molar ratio between the polymers (resulting in excess cysteine or thioester moieties) during micelle formation. Furthermore, in vitro cell experiments demonstrated that fluorescently labeled micelles were successfully taken up by HeLa cells while cell viability remained high even at high micelle concentrations. These results demonstrate the potential of these micelles for drug delivery applications.

The formation of condensed (compacted) protein phases is associated with a wide range of human disorders, such as eye cataracts, amyotrophic lateral sclerosis, sickle cell anaemia and Alzheimer’s disease. However, condensed protein phases have their uses: as crystals, they are harnessed by structural biologists to elucidate protein structures, or are used as delivery vehicles for pharmaceutical applications. The physiochemical properties of crystals can vary substantially between different forms or structures (‘polymorphs’) of the same macromolecule, and dictate their usability in a scientific or industrial context. To gain control over an emerging polymorph, one needs a molecular-level understanding of the pathways that lead to the various macroscopic states and of the mechanisms that govern pathway selection. However, it is still not clear how the embryonic seeds of a macromolecular phase are formed, or how these nuclei affect polymorph selection. Here we use time-resolved cryo-transmission electron microscopy to image the nucleation of crystals of the protein glucose isomerase, and to uncover at molecular resolution the nucleation pathways that lead to two crystalline states and one gelled state. We show that polymorph selection takes place at the earliest stages of structure formation and is based on specific building blocks for each space group. Moreover, we demonstrate control over the system by selectively forming desired polymorphs through site-directed mutagenesis, specifically tuning intermolecular bonding or gel seeding. Our results differ from the present picture of protein nucleation, in that we do not identify a metastable dense liquid as the precursor to the crystalline state. Rather, we observe nucleation events that are driven by oriented attachments between subcritical clusters that already exhibit a degree of crystallinity. These insights suggest ways of controlling macromolecular phase transitions, aiding the development of protein-based drug-delivery systems and macromolecular crystallography.

Mesoporous silica nanoparticles (MSNs) have been explored extensively as solid supports for proteins in biological and medical applications. Small (<200 nm) MSNs with ordered large pores (>5 nm), capable of encapsulating therapeutic small molecules suitable for delivery applications in vivo, are rare however. Here we present small, elongated, cuboidal, MSNs with average dimensions of 90 × 43 nm that possess disk-shaped cavities, stacked on top of each other, which run parallel to the short axis of the particle. Amine functionalization was achieved by modifying the MSN surface with 3-aminopropyltriethoxysilane or 3-[2-(2-aminoethylamino)ethylamino]propyltrimethoxysilane (AP-MSNs and AEP-MSNs) and were shown to have similar dimensions to the nonfunctionalized MSNs. The dimensions of these particles, and their large surface areas as measured by nitrogen adsorption–desorption isotherms, make them ideal scaffolds for protein encapsulation and delivery. We therefore investigated the encapsulation and release behavior for seven model proteins (α-lactalbumin, ovalbumin, bovine serum albumin, catalase, hemoglobin, lysozyme, and cytochrome c). It was discovered that all types of MSNs used in this study allow rapid encapsulation, with a high loading capacity, for all proteins studied. Furthermore, the release profiles of the proteins were tunable. The variation in both rate and amount of protein uptake and release was found to be determined by the surface chemistry of the MSNs, together with the isoelectric point (pI), and molecular weight of the proteins, as well as by the ionic strength of the buffer. These MSNs with their large surface area and optimal dimensions provide a scaffold with a high encapsulation efficiency and controllable release profiles for a variety of proteins, enabling potential applications in fields such as drug delivery and protein therapy.

The spontaneous one-step synthesis of hollow nanocages and nanotubes from spherical and cylindrical micelles based on poly(acrylic acid)-b-polylactide (P(AA)-b-P(LA)) block copolymers (BCPs) has been achieved. This structural reorganization, which occurs simply upon drying of the samples, was elucidated by transmission electron microscopy (TEM) and atomic force microscopy (AFM). We show that it was necessary to use stain-free imaging to examine these nanoscale assemblies, as the hollow nature of the particles was obscured by application of a heavy metal stain. Additionally, the internal topology of the P(AA)-b-P(LA) particles could be tuned by manipulating the drying conditions to give solid or compartmentalized structures. Upon resuspension, these reorganized nanoparticles retain their hollow structure and display significantly enhanced loading of a hydrophobic dye compared to the original solid cylinders.

Soluble macromolecules are essential to Nature's control over biomineral formation. Following early studies where macromolecules rich in aspartic and glutamic acid were extracted from nacre, research has focused on the use of negatively charged additives to control calcium carbonate precipitation. It is demonstrated that the positively charged additive poly(allylamine hydrochloride) (PAH) can also cause dramatic changes in calcite morphologies, yielding thin films and fibers of CaCO3analogous to those produced with poly(aspartic acid) via a so‐called PILP (polymer‐induced liquid precursor) phase. The mechanism by which PAH induces these effects is investigated using a range of techniques including cryo transmission electron microscopy (TEM), Raman microscopy, and thermogravimetric analysis, and the data show that hydrated Ca2+/PAH/CO32−droplets initially form in solution, before coalescing and ultimately crystallizing to give calcite, together with small quantities of vaterite. It is suggested that it is the initial formation of hydrated Ca2+/PAH/CO32−droplets that is key to this process, rather than a specific polymer/mineral interaction. These results are discussed in terms of their relevance to biomineralization processes and highlight the opportunity for using counter‐ion‐induced phase separation of polyelectrolytes as a method for generating minerals with non‐crystallographic morphologies.

The supramolecular oligomerization of three water‐soluble C3‐symmetrical discotic molecules is reported. The compounds all possess benzene‐1,3,5‐tricarboxamide cores and peripheral GdIII–DTPA (diethylene triamine pentaacetic acid) moieties, but differ in their linker units and thus in their propensity to undergo secondary interactions in H2O. The self‐assembly behavior of these molecules was studied in solution using circular dichroism, UV/Vis spectroscopy, nuclear magnetic resonance, and cryogenic transmission electron microscopy. The aggregation concentration of these molecules depends on the number of secondary interactions and on the solvophobic character of the polymerizing moieties. Hydrophobic shielding of the hydrogen‐bonding motif in the core of the discotic is of paramount importance for yielding stable, helical aggregates that are designed to be restricted in size through anti‐cooperative, electrostatic, repulsive interactions.

The investigation of solution‐borne nanostructures by transmission electron microscopy (TEM) is a frequently used analytical method in materials chemistry. In many cases, the preparation of the TEM sample involves drying and staining steps, and the collection of images leads to the interaction of the specimen with the electron beam. Both aspects call for cautious interpretation of the resulting electron micrographs. Alternatively, a near‐native solvated state can be preserved by cryogenic vitrification and subsequent imaging by low‐dose cryogenic TEM. In this Minireview, we provide a critical analysis of sample preparation, and more importantly, of the acquisition and interpretation of electron micrographs. This overview should provide a framework for the application of (cryo)‐TEM as a powerful and reliable tool for the analysis of colloidal and self‐assembled structures with nanoscopic dimensions.

In der Materialchemie werden in Lösung gezüchtete Nanostrukturen oft mithilfe der Transmissionselektronenmikroskopie (TEM) untersucht. Häufig werden die TEM‐Proben bei der Probenvorbereitung getrocknet und kontrastiert, und bei der Bildaufnahme selbst kommt es zur Wechselwirkung zwischen der Probe und dem Elektronenstrahl. Beide Prozesse rufen zur Vorsicht bei der Interpretation der erhaltenen elektronenmikroskopischen Aufnahmen auf. Alternativ dazu kann durch kryogene Probenpräparation und anschließende Abbildung mit kryogener Niederdosis‐TEM ein beinahe nativer solvatisierter Zustand konserviert werden. In unserem Kurzaufsatz geben wir eine kritische Analyse der Probenvorbereitung und, noch wichtiger, der Datenaufnahme und Interpretation von elektronenmikroskopischen Aufnahmen. Die Übersicht soll auch Leitlinien für die Anwendung von (Kryo‐)TEM als leistungsstarkes und zuverlässiges Hilfsmittel für die Analyse kolloidaler und selbstorganisierter Strukturen mit Abmessungen im Nanometerbereich bieten.

The peculiar properties of osmotically shrunken liposomes acting as magnetic resonance imaging–chemical exchange saturation transfer (MRI–CEST) contrast agents have been investigated. Attention has been primarily devoted to assessing the contribution arising from encapsulated and incorporated paramagnetic lanthanide(III)‐based shift reagents in determining the chemical shift of the intraliposomal water protons, which is a relevant factor for generating the CEST contrast. It is demonstrated that a highly shifted resonance for the encapsulated water can be attained by increasing the percentage of the amphiphilic shift reagent incorporated in the liposome bilayer. It is also demonstrated that the shift contribution arising from the bulk magnetic susceptibility can be optimized through the modulation of the osmotic shrinkage. In terms of sensitivity, it is shown that the saturation transfer efficiency can be significantly improved by increasing the size of the vesicle, thus allowing a high number of exchangeable protons to be saturated. In addition, the role played by the intensity of the saturating radiofrequency field has also been highlighted.

The self-organization behavior of an amphiphilic sexithiophene bearing amide functionalities is studied and compared to that of a derivative bearing an ester group at the same position. The introduction of hydrogen-bond interactions in assemblies of these p-conjugated oligomers is found to affect the molecular organization both in protic media and in thin deposits on mica. The amphiphilic 2,2';5',2'';5'',2''';5''',2'''';5'''',2'''''-sexithiophene-5,5'''''-dicarboxylic acid bis[(4,7,10,13,16-pentaoxaheptadecyl)amide] forms assemblies in n-butanol and water and partially aggregates in toluene. Spectroscopy reveals that the presence of a hydrogen-bonding moiety increases the thermal stability of the assemblies in n-butanol and even more in water solution. On mica surfaces, the formation of rod-like one-dimensional nanostructures is observed after deposition from toluene solutions. In addition, transmission electron microscopy in combination with selected area electron diffraction shows that in water plate-like structures are formed built from parallel oriented stacks, with a p–p distance of 3.5 Å. Comparison of these data to molecular modeling and quantum chemistry calculations is used to better understand the influence of the amide group on the stacking of these compounds. The introduction of these H-bonding interactions leads to denser and more stable stacks. Furthermore, we show that a derivative of the amide compound, bearing terminal ammonium groups, forms a complex with chiral polyanions in aqueous media such that the sexithiophene segments are stacked in a meta-stable helical fashion with preferred handedness. We observed that poly(glutamate) and DNA generate a chiral sexithiophene assembly. In time the induced chirality disappears, which is explained by the meta-stability of the kinetically formed adduct. This constitutes one step forward towards the controlled formation of functional multi-component systems in aqueous solution.

We report on biohybrid surfactants, termed “giant amphiphiles”, in which a protein or an enzyme acts as the polar head group and a synthetic polymer as the apolar tail. It is demonstrated that the modification of horseradish peroxidase (HRP) and myoglobin (Mb) with an apolar polymer chain through the cofactor reconstitution method yields giant amphiphiles that form spherical aggregates (vesicles) in aqueous solution. Both HRP and Mb retain their original functionality when modified with a single polystyrene chain, but reconstitution has an effect on their activities. In the case of HRP the enzymatic activity decreases and for Mb the stability of the dioxygen myoglobin (oxy‐Mb) complex is reduced, which is probably the result of a disturbed binding of the heme in the apo‐protein or a reduced access of the substrate to the active site of the enzyme or protein.

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Herein we report the synthesis and characterization of hollow silica spheres with a narrow size distribution, uniform wall thickness, and a worm‐like pore structure. The formation of these spheres was monitored by confocal laser scanning microscopy and dynamic light scattering. A model for the molecular build‐up of these silica hollow spheres is derived from these data in combination with studies of the as‐made particles by transmission electron microscopy, scanning electron microscopy, pore size analysis, thermogravimetric analysis, and solid‐state nuclear magnetic resonance. We further demonstrate that these spheres can be used for the encapsulation and subsequent release of different dye molecules.

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Gigantic hollow silica spheres with a hierarchical intra- and inter-particle porosity were obtained from an EO76–PO29–EO76butanolethanolH2O quaternary system, which is unique in its extremely rapid silica condensation and in the resulting hierarchical morphology.

The conformational properties of polymers derived from isocyanodipeptides have been investigated with a combination of model calculations, X-ray diffraction, and circular dichroism spectroscopy. Depending on the configuration of the side chains, defined arrays of hydrogen bonds along the polymeric backbone are formed. This leads to a well-defined conformation as, for example, expressed in the formation of lyotropic liquid-crystalline phases and increased helical stability. Upon the disruption of the hydrogen bonds by a strong acid, a less well-defined macromolecular conformation is observed. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1725–1736, 2003

The ABA amphiphilic block copolymers, polyhydroxyethyl methacrylate-block-methylphenylsilane-block-hydroxyethyl methacrylate PHEMA–PMPS–PHEMA and polyoligoethylene glycol methyl ether methacrylate-block-methylphenylsilane-block-oligoethylene glycol methyl ether methacrylate POEGMA–PMPS–POEGMA were successfully synthesised viaatom transfer radical polymerisation ATRP. Macroinitiators suitable for the ATRP of oligoethylene glycol) methyl ether methacrylate and 2-hydroxyethyl methacrylate were synthesised from the condensation reaction of α,ω-dihalopolymethylphenylsilane and 2′-hydroxyethyl 2-bromo-2-methylpropanoate. The copolymers were characterised using 1H NMR and 13C NMR spectroscopy and molecular weight characteristics were determined using size exclusion chromatography and 1H NMR. The aggregation behaviour of some of the copolymers in water was studied using transmission and scanning electron microscopy and dynamic light scattering. These revealed the prevalent aggregate species to be micelles. Larger aggregates of 300–1000 nm diameter were also observed. The UV induced degradation of the aggregates was studied by UV-Vis spectroscopy. The thermal behaviour of selected copolymers was studied by differential scanning calorimetry and microphase separation of the two components was demonstrated.

The ABA amphiphilic block copolymers, poly(hydroxyethyl methacrylate-block-methylphenylsilane-block-hydroxyethyl methacrylate) (PHEMA–PMPS–PHEMA) and poly[oligo(ethylene glycol) methyl ether methacrylate-block-methylphenylsilane-block-oligo(ethylene glycol) methyl ether methacrylate] (POEGMA–PMPS–POEGMA) were successfully synthesised via atom transfer radical polymerisation (ATRP). Macroinitiators suitable for the ATRP of oligo(ethylene glycol) methyl ether methacrylate and 2-hydroxyethyl methacrylate were synthesised from the condensation reaction of α,ω-dihalopolymethylphenylsilane and 2'-hydroxyethyl 2-bromo-2-methylpropanoate. The copolymers were characterised using 1H NMR and 13C NMR spectroscopy and molecular weight characteristics were determined using size exclusion chromatography and 1H NMR. The aggregation behaviour of some of the copolymers in water was studied using transmission and scanning electron microscopy and dynamic light scattering. These revealed the prevalent aggregate species to be micelles. Larger aggregates of 300–1000 nm diameter were also observed. The UV induced degradation of the aggregates was studied by UV-Vis spectroscopy. The thermal behaviour of selected copolymers was studied by differential scanning calorimetry and microphase separation of the two components was demonstrated.

The assignment of the helix sense in poly(isocyano amino acids) and poly(isocyano peptides) using circular dichroism (CD) spectroscopy is hampered due to overlap of signals arising from the polymer backbone and the side chains. By comparing the CD spectrum of an L-alanine based polyisocyanide containing a spectator group (i.e. a diazochromophore) with the CD spectra of other L-alanine-based polyisocyanides a right-handed (P) helical backbone geometry has been assigned to these polymers. Models of the 41 helical conformation of a 20 residue polyisocyanide (top) and the syndio conformation of a 12 residue polyisocyanide (bottom).

Poly(propylene imine) dendrimers that are modified with long alkyl chains self‐assemble to form well‐defined aggregates. The geometry and surface chemistry of the dendrimer assemblies can be varied through the addition of surfactants. These dendrimer/surfactant aggregates can be tuned to template the formation of the different phases of calcium carbonate. The use of octadecylamine results in the formation of polyhedral aggregates that become embedded within an amorphous calcium carbonate phase that persists in competition with the thermodynamic product, calcite. In combination with hexadecyltrimethylammonium bromide, small spherical aggregates are formed that induce the formation of vaterite. The use of the negatively charged surfactant SDS results in growth retardation by the Ca2+‐induced agglomeration of dendrimer/surfactant aggregates into giant spherical particles. Eventually these particles become overgrown by rhombohedral calcite.

The synthesis of three novel cationic gemini surfactants (10, 12, and 14) based on tartaric acid appended with biocompatible palmitoyl tails and head groups is described, and their aggregation in water, monolayer behaviour, DNA binding, and gene transfection activities are reported. The monolayer studies showed that the molecular area of the surfactants is determined by the head group, as it increased going from the ethylenediamine head group of 10 via the lysine head group of 12 to the combined lysine/ethylenediamine head group of 14. Electron microscopy showed that the surfactants with the smaller head groups (10 and 12) form plate-like structures, probably stacked bilayers, in line with the shape-structure concept, whereas no structures are observed for the largest surfactant 14. A CD spectroscopic titration of λ-phage DNA with surfactants 12 and 14 showed that there was some interaction, although the secondary structure of the DNA was hardly affected. The effects of the novel surfactants and commercially available DOTAP [N-(2,3-dioleoyloxypropyl)-N,N,N-trimethylammonium methyl sulfate] were identical when compared on the basis of charge complimentarity, indicating that the complexation of DNA with the surfactant is a process of ion exchange. DNA binding was confirmed by the ability of all surfactants (10, 12, and 14) to release ethidium bromide from its complex with DNA in an agarose gel electrophoresis experiment. Both lysine-containing surfactants 12 and 14 showed activity in a luciferase gene-transfection assay but this was accompanied by a considerable toxicity.

The synthesis of 3,4-ethylenedioxythiophene (EDOT) derivatives bearing functional groups is described. Their electrochemical characteristics were investigated with cyclic voltammetry and ultraviolet–visible spectroscopy. Various copolymers of EDOT and modified EDOT containing hydroxyl groups were electrochemically prepared. The ability to bind proteins to the surface of these copolymers was investigated through the covalent coupling of glucose oxidase. The obtained materials were used as working electrodes and were shown to be able to amperometrically detect glucose under aerobic and anaerobic conditions. Possible applications of these materials as biosensors are discussed. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 738–747, 2002; DOI 10.1002/pola.10159

The synthesis and characterization of polymers derived from isocyanopeptides are described. Optically pure dipeptides based on alanine and glycine were equipped with an isocyano function and subsequently polymerized with a Ni(II) catalyst. Infrared and NMR spectroscopy indicated that the side chains of the polymers were connected by well-defined arrays of intramolecular hydrogen bonds. The weight-average molecular weights of the polymers were determined by atomic force microscopy to be 200–400 kg/mol (polydispersity index = 1.4–1.7). © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 4255–4264, 2001

The synthesis and characterization of styrene-based polymers and copolymers containing pendant tetra(ethylene glycol) and phosphorylcholine groups is reported. These polymers are obtained via radical polymerization reactions using α,α'-azobis(isobutyronitrile) as the initiator, and are developed as protective biocompatible coatings for implantable biosensors. Cell morphology studies show that none of the synthesized polymers and copolymers are toxic, and that the rate of cell growth can be tuned by changing the monomer composition. The presence of tetra(ethylene glycol) groups in the coatings lowers the protein adsorption, thereby influencing the rate of cell growth. An equally profound effect is observed when a low percentage of phosphorylcholine groups is present in the polymers. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 468–474, 2001

Hydrogen bonding between urea groups of amphiphilic tri-block copolymers considerably affects their self-assembly in water, which results in a strong modification of morphology and viscosity of aqueous solutions; the hydrogen bonding motif in these amphiphilic copolymers allows molecular recognition of small molecules with complementary hydrogen bonding units.

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No Abstract Supporting information for this article is available on the WWW under http://www.angewandte.com or from the author.

Association of streptavidin and two biotinylated polystyrene chainsto form protein–polymer hybrids results in “giant amphiphiles” (see first step of schematic representation). Functionality can be introduced by the complexation of other biotinylated molecules to the remaining binding sites of streptavidin (second step).

No Abstract Supporting information for this article is available on the WWW under http://www.angewandte.com or from the author.

Ring opening of 1-alkanoyl-2-phenoxymethylaziridines by phosphate ions yielding self-assembling phospholipid analogues proceeds in an autocatalytic fashion and with complete regioselectivity at an organic–aqueous interface.

In the presence of octadecylamine, poly(propylene imine) dendrimers modified with long alkyl chains self-assemble to form well-defined aggregates that stabilise for periods exceeding 14 days the normally unstable amorphous calcium carbonate (ACC) which persists in competition with the thermodynamic product, calcite.

In the presence of octadecylamine, poly(propylene imine) dendrimers modified with long alkyl chains self-assemble to form well-defined aggregates that stabilise for periods exceeding 14 days the normally unstable amorphous calcium carbonate (ACC) which persists in competition with the thermodynamic product, calcite.

Surface plasmon resonance is used to monitor the kinetics of deposition and antibody binding of self-assembled monolayers of cysteine-containing peptides on gold surfaces.

Review: ca. 80 refs.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

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The cover picture showsthe process of calcium carbonate mineralization on dendrimer/octadecylamine aggregates. Amphiphilic dendrimers complex octadecylamine to form polyhedral aggregates. These aggregates template the formation and stabilization of amorphous calcium carbonate, which normally transforms into a crystalline phase within four hours. In a secondary growth process, hybrid particles are formed in which the amorphous particles are embedded within a crystalline phase. For more details see the article by N. A. J. M. Sommerdijk et al. on p. 2561 ff.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.