Volume 87, Issue 8

Otoconia (calcite-based biominerals) are part of the sensory system in the inner ear of vertebrates, acting as gravity receptors responding to linear accelerations. Biomimetic otoconia are grown by double-diffusion into gelatine-gel matrices, and represent the first example of successful imitation of a biomineral, not only in outer shape but also in composite structure and hierarchical inner architecture. Biomimetic and biogenic (human) otoconia are investigated by X-ray methods, chemical analytics, ESEM, and TEM. Shape development (morphogenesis) as well as (partial) dissolution of the calcite component of the composite underline the hierarchical inner architecture built of more dense rhombohedral branches (with plane end-faces) and a rounded, more porous belly area. Atomistic simulations are performed in order to get insight into very first nucleation steps. Based on the detailed observations made up to now, first assumptions for the function of otoconia are developed, including the questions of density distribution within the volume of the specimen, the surrounding endolymph, as well as anchoring and interconnections of otoconia. A final point concerns the degeneration of otoconia which is caused by complexing agents and/or changes in ion concentrations (and pH) of the endolymph.

Despite significant investment in tissue engineering over the past 20 years, few tissue engineered products have made it to market. One of the reasons is the poor control over the 3D arrangement of the scaffold’s components. Biofabrication is a new field of research that exploits 3D printing technologies with high spatial resolution for the simultaneous processing of cells and biomaterials into 3D constructs suitable for tissue engineering. Cell-encapsulating biomaterials used in 3D bioprinting are referred to as bioinks. This review consists of: (1) an introduction of biofabrication, (2) an introduction of 3D bioprinting, (3) the requirements of bioinks, (4) existing bioinks, and (5) a specific example of a recombinant spider silk bioink. The recombinant spider silk bioink will be used as an example because its unmodified hydrogel format fits the basic requirements of bioinks: to be printable and at the same time cytocompatible. The bioink exhibited both cytocompatible (self-assembly, high cell viability) and printable (injectable, shear-thinning, high shape fidelity) qualities. Although improvements can be made, it is clear from this system that, with the appropriate bioink, many of the existing faults in tissue-like structures produced by 3D bioprinting can be minimized.

The most fundamental phenomena in the immobilising of biomolecules on the nanostructured materials for energy, environmental and health applications are the control of interfaces between the nanostructures/nanopores and the immobilized biomaterials. Thus, the throughput of all those biobased nanostructured materials and devices can be improved or controlled by the enhanced geometric area of the nanostructured interfaces if an efficient immobilization of the biomolecules is warranted. In this respect, an accurate control of the geometry (size, porosity, etc.) and interfaces is primordial to finding the delicate balance between large/control interface areas and good immobilization conditions. Here, we will show how the atomic layer deposition (ALD) can be used as a tool for the creation of controlled nanostructured interfaces in which the geometry can be tuned accurately and the dependence of the physical-chemical properties on the geometric parameters can be studied systematically in order to immobilize biomolecules. We will show mainly examples of how these methods can be used to create single nanopores for mass spectroscopy and DNA sequencing, and membrane for gas separation and water treatment in which the performance varies with the nanostructure morphologies/interfaces and the immobilization conditions.

Hydrophilicity and hydrophobicity are among the most important concepts in surface chemistry. Samuel and co-workers reported the measure of interactive forces between water and 20 different surfaces using the microbalance technique. Results showed that the wetting force correlates well to the advancing contact angle (θ A ), the larger the θ A the lower the surface wettability. The adhesion force, measured when the water and surface first separates, correlates well to the receding contact angle (θ R ), the larger the θ R the smaller the surface adhesion. The data also reveals that small residual water droplets are observed after the water droplet and the surface separate for surfaces with θ R < 90°. This indicates high water affinity for these surfaces. No residual water droplet is observed for surfaces with θ R > 90°. From the basic meaning of philicity-phobicity, θ R ∼90° is proposed as the new cut-off between hydrophilicity and hydrophobicity. The main driver for hydrophobicity is attributed to the high water surface tension. The merit of this proposed definition is discussed. Since wetting interaction becomes zero at θ A ≥ 145°, surfaces with θ R > 90° and θ A ≥ 145° can further be defined as superhydrophobic. The extension of this approach to define oleophilicity/phobicity and superoleophobicity with hexadecane is discussed.

In this research, crosslinked hybrids of a newly invented bio-based elastomer poly(di-isoamyl itaconate- co -isoprene) (PDII) and 3,9-bis[1,1-dimethyl-2{β-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy}ethyl]-2,4,8,10-tetraoxaspiro[5,5]-undecane (AO-80) were designed and prepared by the mechanical kneading of the PDII/AO-80 hybrids at a temperature higher than the melting point of AO-80, followed by the crosslinking of PDII during the subsequent hot-pressing/vulcanization process. The microstructure, morphology, and mechanical properties of the hybrids were systematically investigated in each preparation stage by using DSC, FTIR, XRD, SEM, DMTA, and tensile testing. Part of the AO-80 molecules formed an AO-80-rich phase, but most of them dissolved in the PDII to form a very fine dispersion in amorphous form. The results of FTIR and DSC indicated that strong intermolecular interactions were formed between the PDII and the AO-80 molecules. Each PDII/AO-80 crosslinked hybrid showed a single transition with a higher glass transition temperature and significantly higher loss value (tan δ) than the neat PDII because of intermolecular interactions between the PDII and the AO-80 molecules. For instance, tan δ of PDII/AO-80 consisting of 100 phr AO-80 achieved 2.6 times as neat PDII. The PDII/AO-80 crosslinked hybrids with applicability at room temperature are potential bio-based damping materials for the future.

In biology, an immense diversity of protein structural and functional motifs originates from only 20 common proteinogenic native amino acids arranged in various sequences. Is it possible to attain the same diversity in electronic materials based on organic macromolecules composed of non-native residues with different characteristics? This publication describes the design, preparation and characterization of non-native aromatic β-amino acid residues, i.e. derivatives of anthranilic acid, for polyamides that can efficiently mediate hole transfer. Chemical derivatization with three types of substituents at two positions of the aromatic ring allows for adjusting the energy levels of the frontier orbitals of the anthranilamide residues over a range of about one electronvolt. Most importantly, the anthranilamide residues possess permanent electric dipoles, adding to the electronic properties of the bioinspired conjugates they compose, making them molecular electrets.

Bionanocomposites in the self-organized regime are prepared when chitosan is gradually charged in the course of progressive change of pH by hydrolyzing D -glucono- δ -lactone in solutions of nanoparticles bearing negative charges on their surface. This novel approach is applicable to the formation of monolithic hydrogels and films. Here bionanocomposites of chitosan with clay nanoparticles of saponite and sepiolite having various geometry and with oxidized multiwall carbon nanotubes are considered. Structural organization of hydrogels and films is studied by scanning and transmission electron microscopy as well as small angle X-ray scattering. Jellification is caused by generation of three-dimensional network from fibrils, whereas films have pronounced stratified layer (nacre-like) structure from stacked nanoparticles and aligned chitosan macromolecules. Special attention is paid to mechanical properties of films that are improved drastically with introducing nanoparticles.

In nature, several plants and insects, such as the Rosa montana petals or the gecko foot, are highly hydrophobic but with an extremely high water adhesion. These properties are called parahydrophobic. Here, in order to reproduce such properties we have developed original 3,4-ethylenedioxypyrrole monomers containing branched alkyl chains in order to have intrinsically hydrophilic polymers. In certain conditions, the electrodeposited conducting polymer films are parahydrophobic due to the presence fibrous structures forming large agglomerates. On such surfaces, a water droplet deposited on them remains stuck even after a substrate inclination of 180°. Such properties are extremely interesting for applications in water harvesting, for example.

Porous architectured electrodes are intensely investigated for promoting electrochemical performance. Besides the high surface area, mass transport plays an irreplaceable role in the architecture assisting effect, which is, however, far beyond expression due to the complexity and irregularity of various electrode materials. Here, we took advantage of elaborate architectures from butterfly wings and obtained carbon electrode with ridge/pore array hierarchical architecture ( ridge/pore-C ) using a carbonizing-graphite coating method. A basic one-electron transfer process using the redox couple ferri/ferrocyanide as a benchmark under cyclic voltammetric conditions was conducted. The peak potential separation for ridge/pore-C was decreased by 117 mV compared to its non-architectured counterpart, with obvious enhancement of peak current density, indicating prominent beneficial impact on electrochemical responses. Further finite element simulation demonstrated the additional lateral diffusion within the ridge domain and partial thin layer diffusion within the pore array domain of ridge/pore-C , and simultaneously verified the experimental results. By constructing and investigating the well-organized porous architecture for affecting cyclic voltammogram, this work provides a prototype and cost-effective method for structural design of efficient electrodes by drawing inspiration from nature.

Glucosyloxymethylfurfural (GMF) is the glucosylated analogue of hydroxymethylfurfural (HMF), and is obtained in one step from the very available disaccharide isomaltulose. This account gives an overview on the preparation and the uses of GMF towards architectures containing a carbohydrate moiety and shows that rather elaborated targets can be synthesized from GMF in very short sequences. A special focus is made on carbon–carbon formation on the aldehyde group leading to new biobased acrylic derivatives by the Baylis–Hillman reaction.

The primary objective of this Glossary of Terms Used in Neurotoxicology is to give clear definitions for those who contribute to studies relevant to neurotoxicology, or must interpret them, but are not themselves neurotoxicologists, neuroscientists or physicians. This applies especially to chemists who need to understand the literature of neurotoxic effects of substances without recourse to a multiplicity of other glossaries or dictionaries. The Glossary includes terms related to basic and clinical neurology insofar as they are necessary for a self-contained document, and particularly terms related to diagnosing, measuring, and understanding effects of substances on the central and peripheral nervous systems. The glossary consists of about 800 terms as primary alphabetical entries, and includes Annexes of common abbreviations, and examples of chemicals with known effects on the nervous system. The authors hope that among the groups who will find this glossary helpful, in addition to chemists, are toxicologists, pharmacologists, medical practitioners, risk assessors, and regulatory authorities. In particular, it should facilitate the worldwide use of chemistry in relation to occupational and environmental risk assessment.