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A comprehensive understanding of the interactions between organic molecules and a metal oxide surface is essential for an efficient surface modification and the formation of organic–inorganic hybrids with technological applications ranging from heterogeneous catalysis and biomedical templates up to functional nanoporous matrices. In this work, first-principles calculations supported by experiments are used to provide the microstructural characteristics of (100) surfaces of zinc oxide single crystals modified by azide terminated hydrocarbons, which graft on the oxide through a thiol group. On the computational side, we evaluate the specific interactions between the surface and the molecules with the chemical formula N3(CH2)nSH, with n = 1, 3, 6, 9. We demonstrate that the molecules chemisorb on the bridge site of ZnO(100). Upon adsorption, the N3(CH2)nSH molecules break the neutral (Znδ+–Oδ−) dimers on ZnO(100) resulting in a structural distortion of the ZnO(100) substrate. The energy decomposition analysis revealed that such structure distortion favors the adsorption of the molecules on the surface leading to a strong correlation between the surface distortion energy and the interaction energy of the molecule. An azide-terminated thiol with three methylene groups in the hydrocarbon chain N3(CH2)3SH was synthesized, and the assembly of this linker on ZnO surfaces was confirmed through atomic force microscopy. The bonding to the inorganic surface was examined via X-ray photoelectron spectroscopy (XPS). Clear signatures of the organic components on the oxide substrates were observed underlying the successful realization of thiol-grafting on the metal oxide. Temperature-dependent and angle-resolved XPS were applied to examine the thermal stability and to determine the thickness of the grafted SAMs, respectively. We discuss the high potential of our hybrid materials in providing further functionalities towards heterocatalysis and medical applications.

The ubiquity of portable electronics underlines the importance of high-performance flexible metal-ion batteries and the necessity of their development. Considering their ecological footprint, the application of eco-friendly recyclable battery components has become the greatest challenge and the focal point of research. However, less attention has been devoted to the development of shape-conformable separators with minimal impact on the battery performance and the environment. It is therefore imperative to develop a rational design of next-generation eco-friendly separators with an optimized structure–performance relationship. In this work, a highly flexible and eco-friendly cellulose-nanofiber aerogel (CNF-AG) separator is developed and its dynamic behavior in battery cells is assessed. The tailored channel-like structure with a meso- and macroporosity of 99.5% and good mechanical stability results in superior performance to the commercial glass fiber (GF) membranes and other cellulose-based separators. Its structure with a well-connected pore network and affinity to carbonate-based and ionic liquid electrolytes realize an electrolyte uptake of 12 000%. Furthermore, an effective diffusion coefficient of 1.70 × 10–10 m2 s–1, only 16% lower than that of the bulk electrolyte, yielded an ionic conductivity of 2.64 mS cm–1. Assessing the CNF-AG in lithium-ion batteries (LIBs) revealed a stable interfacial resistance over time, reaching 380 Ω, one-third of that obtained for GF. Accordingly, superior electrochemical performance is observed, achieving good cycling stability up to 200 cycles. Moreover, its applicability in aluminum-ion batteries is demonstrated. The outstanding structure–performance relationships of the developed CNF-AG indicate its superiority as a shape-conformable biodegradable separator suitable for metal-ion batteries.

The manifold applications of porous materials, such as in storage, separation, and catalysis, have led to an enormous interest in their cost-efficient preparation. A promising strategy to obtain porous materials with adjustable pore size and morphology is to use templates exhibiting the appropriate nanostructure. In this study, close-packed polystyrene (PS) nanoparticles, synthesized by emulsion polymerization, were used to produce porous PS and ZnO inverse opals. The size and distribution of the polystyrene nanoparticles, characterized by dynamic light scattering (DLS), small-angle neutron scattering (SANS), and scanning electron microscopy (SEM), were controlled via the concentration of sodium dodecyl sulfate (SDS). Systematic measurements of the water/styrene-interfacial tension show that the critical micelle concentration (CMC) of the ternary water–styrene–SDS system, which determines whether monodisperse or polydisperse PS particles are obtained, is considerably lower than that of the binary water–SDS system. The assemblies of close-packed PS nanoparticles obtained via drying were then studied by small-angle X-ray scattering (SAXS) and SEM. Both techniques prove that PS nanoparticles synthesized above the CMC result in a significantly unordered but denser packing of the particles. The polystyrene particles were subsequently used to produce porous polystyrene and ZnO inverse opals. While the former consists of micrometer-sized spherical pores surrounded by extended open-cellular regions of mesopores (Rpore ≈ 25 nm), the latter are made of ZnO-nanoparticles forming a structure of well-aligned interconnected pores., Deutsche Forschungsgemeinschaft, Projekt DEAL

Nucleation behavior of amorphous Si–B–C–N ceramics derived from boron-modified polyvinylsilazane procusors was systematically investigated by transmission electron microscopy (TEM) combined with spatially-resolved electron energy-loss spectroscopy (EELS) analysis. The ceramics were pyrolyzed at 1000 °C followed by further annealing in N2, and SiC nano-crystallites start to emerge at 1200 °C and dominate at 1500 °C. Observed by high-angle annular dark-field imaging, bright and dark clusters were revealed as universal nano-structured features in ceramic matrices before and after nucleation, and the growth of cluster size saturated before reaching 5 nm at 1400 °C. EELS analysis demonstrated the gradual development of bonding structures successively into SiC, graphetic BNCx and Si3N4 phases, as well as a constant presence of unexpected oxygen in the matrices. Furthermore, EELS profiling revealed the bright SiC clusters and less bright Si3N4-like clusters at 1200–1400 °C. Since the amorphous matrix has already phase separated into SiCN and carbon clusters, another phase separation of SiCN into SiC and Si3N4-like clusters might occur by annealing to accompany their nucleation and growth, albeit one crystallized and another remained in amorphous structure. Hinderance of the cluster growth and further crystallization was owing to the formation of BNCx layers that developed between SiC and Si3N4-like clusters as well as from the excessive oxygen to form the stable SiO2.

Recently, there has been growing attention and effort to search for new microbicidal drugs which present different mode of action from those already existing, as an alternative to the global threat of fungal and bacterial multi drug resistance (MDR). Here we propose biological synthesis of SnO₂ nanoparticles using mammalian cells as an economic and ecofriendly platform. This presents a novel biogenic method for SnO₂ synthesis using metal binding peptides extracted from MCF-7 human cancer cells, which induces the biomineralization of SnO₂ nanoparticles. A series of electron donor functional groups and metal binding sites in these peptides reacts with Sn2+ ions and directs the growth of SnO₂ nanoparticles without addition of toxic redox and capping agents in the reaction system. Since peptides present reactive sites in aqueous solution at room temperature, a facile reaction environment can be easily achieved. Furthermore, by tuning the reactants' concentration and pH, the size, shape and 3D-structures of SnO₂ nanoparticles can be controlled. Peptides also ensure biocompatibility, and SnO₂ nanoparticles provide antibacterial properties, which broadens their applications in biomedical fields.

Catalytically active colloids are model systems for chemical motors and active matter. It is desirable to replace the inorganic catalysts and the toxic fuels that are often used with biocompatible enzymatic reactions. However, compared to inorganic catalysts, enzyme-coated colloids tend to exhibit less activity. Here, we show that the self-assembly of genetically engineered M13 bacteriophages that bind enzymes to magnetic beads ensures high and localized enzymatic activity. These phage-decorated colloids provide a proteinaceous environment for directed enzyme immobilization. The magnetic properties of the colloidal carrier particle permit repeated enzyme recovery from a reaction solution, while the enzymatic activity is retained. Moreover, localizing the phage-based construct with a magnetic field in a microcontainer allows the enzyme-phage-colloids to function as an enzymatic micropump, where the enzymatic reaction generates a fluid flow. This system shows the fastest fluid flow reported to date by a biocompatible enzymatic micropump. In addition, it is functional in complex media including blood, where the enzyme-driven micropump can be powered at the physiological blood-urea concentrations.

The increasing demand for high energy, sustainable and safer rechargeable electrochemical storage systems for portable devices and electric vehicles can be satisfied by the use of hybrid batteries. Hybrid batteries, such as magnesium-lithium-ion batteries (MLIBs), using a dual-salt electrolyte take advantage of both the fast Li

Active self-propelled colloidal populations induce time-dependent three-dimensional fluid flows, which alter the rheological (viscoelastic) properties of their fluidic media. Researchers have also studied passive colloids mixed with bacterial suspensions to understand the hydrodynamic coupling between active and passive colloids. With recent developments in biological cell-driven biohybrid microswimmers, different type biological microswimmer (e.g., bacteria and algae) populations need to interact fluidically with each other in the same fluidic media, while such interactions have not been studied experimentally yet. Therefore, we report the swimming behavior of two opposite types of biological microswimmer (active colloid) populations: Chlamydomonas reinhardtii (C. reinhardtii) algae (puller-type microswimmers) population in coculture with Escherichia coli (E. coli) bacteria (pusher-type microswimmers) population. We observed noticeable fluidic coupling deviations from the existing understanding of passive colloids mixed with bacterial suspensions previously studied in the literature. The fluidic coupling among puller- and pusher-type microswimmers led to nonequilibrium fluctuations in the fluid flow due to their opposite swimming patterns. Such coupling could be the main reason behind the shift in motility behaviors of these two opposite-type swimmer populations suspended in the same fluidic media., NA

The rising demand for flexible electronic devices requires the development of bendable lithium-ion batteries (LIBs), in which paperlike electrodes exhibit a high electrochemical storage capacity coupled with excellent mechanical flexibility. Along this line, this work proposes a novel fabrication method for self-supporting paperlike anodes, which are exclusively made from active materials. Metastable SnClx(OH)yOz precursor particles and graphene oxide (GO) sheets are assembled in a facile and low-cost way, leading to paperlike hybrid materials. Subsequent annealing at 500 °C under an argon atmosphere reduces the GO simultaneously with the transformation of the metastable precursor to tin dioxide (SnO2) via a direct oxygen transfer mechanism between the two components. This oxygen transfer is accompanied by the anchoring of the SnO2 particles onto the reduced GO (rGO) sheets, yielding an excellent synergy among mechanical stability, electrical conductivity, and electrochemical capacity of the hybrid materi...

Protein- and peptide-based manufacturing of self-assembled supramolecular functional materials has been a formidable challenge for biomedical applications, being complex in structure and immunogenic in nature. In this context, self-assembly of short amino acid sequences as simplified building blocks to design metal–biomolecule frameworks (MBioFs) is an emerging field of research. Here, we report a facile, bioinspired route of anisotropic nanostructure synthesis using gold binding peptides (10–15mers) secreted by cancer cells. The bioinformatics tool i-TASSER predicts the effect of amino acid sequences on metal binding sites and the secondary structures of the respective peptide sequence. Electron microscopy, X-ray, infrared, and Raman spectroscopy validated the versatile anisotropic gold nanostructures and the metal–bioorganic nature of this biomineralization. We studied the influence of precursor salt, pH, and peptide concentration on the evolution of nanoleaf, nanoflower, nanofiber, and dendrimer-like a...

Polystyrene (PS) nanofoams, prepared following the nanofoams continuity inversion of dispersions (NF-CID) principle, were utilized for the synthesis of nanoporous organic/inorganic hybrid materials. The pore size and morphology of the PS foams were found to depend on the NF-CID parameters: temperature, exposure time, and the expansion process. With this knowledge, PS foams with a pore size of 1 μm were mineralized with ZnO from a methanol precursor solution comprising zinc acetate dihydrate. Scanning electron microscopy (SEM) coupled with energy-dispersive X-ray (EDX) was used to characterize both the pure PS nanofoam and the hybrid material. The formation of a ZnO layer on the pore walls of the polymer foams was confirmed, while the general structure of the foam was retained. Uniaxial compression measurements revealed larger values of the E modulus and the yield stress for the porous PS/ZnO hybrid material compared to the pure polymer foam.

The demand to outperform current technologies pushes scientists to develop novel strategies, which enable the fabrication of materials with exceptional properties. Along this line, lightweight structural materials are of great interest due to their versatile applicability as sensors, catalysts, battery electrodes, and acoustic or mechanical dampers. Here, we report a strategy to design ultralight (ρ = 3 mg/cm3) and hierarchically structured ceramic scaffolds of macroscopic size. Such scaffolds exhibit mechanical reversibility comparable to that of microscopic metamaterials, leading to a macroscopically remarkable dynamic mechanical performance. Upon mechanical loading, these scaffolds show a deformation mechanism similar to polyurethane foams, and this resilience yields ultrahigh damping capacities, tan δ, of up to 0.47.

A surfactant-less, seed mediated, biological synthesis of two dimensional (2-D) nanoribbons in the presence of breast cancer cells (MCF7) is demonstrated. The diameter and yield of nanoribbons are tunable via seeds and gold precursor concentration. Such crystalline nanoribbons serve to enhance the Raman signals over MCF7 cells. The side and slopes of the triangular nanoplatelets fused as nanoribbons exhibit plasmon excitement in quadrupole resonance modes in the infrared region. Consequently, when irradiated with an infrared laser they show an excellent photothermal effect and rapid rise in temperature. The experimental results verified by finite-difference time-domain (FTDT) calculations reveal the presence of wedge-plasmon polaritons propagating along the edges of the nanoribbons. These simulations confirm that long aspect ratio nanoribbon's edges and vertices act as an active optical waveguide, allowing for heat propagation along the long axis, killing cancer cells in the process at lower power doses., Max Planck Institute for Intelligent Systems; Max Planck Society; Alexander von Humboldt Foundation

A Novel approach to fabricate high performance SiCN ceramic nanocomposites containing well dispersed single-walled carbon nanotubes (SWNTs) assisted by room temperature ionic liquids (RTILs) is developed. This method is straightforward, environment-friendly and overcome the typical challenges in the synthesis procedures of SWNTs reinforced precursor derived ceramics (PDCs). The microstructural and elemental characteristics of these ceramic matrix nanocomposites present highly-dispersed SWNTs were introduced and a profitably BN(C) interlayer could be formed in situ between the SWNTs and the ceramic matrix, which resulting in a high performance and a crack free ceramic product. Compared to the pure monolithic SiCN ceramic, the Young's modulus enhanced by ~11% and the electrical conductivities increased up to 0.06 S cm −1 for ceramic composite in the case of the 1 wt% SWNTs was containing. Furthermore, the electrochemical investigation shows the potential application of these SWNTs-IL/Ceramics composites in electrochemical hydrogen storage.

Nowadays, research on electrochemical storage systems moves into the direction of post-lithium-ion batteries, such as aluminum-ion batteries, and the exploration of suitable materials for such batteries. Vanadium pentoxide (V2O5) is one of the most promising host materials for the intercalation of multivalent ions. Here, we report on the fabrication of a binder-free and self-supporting V2O5 micrometer-thick paper-like electrode material and its use as the cathode for rechargeable aluminum-ion batteries. The electrical conductivity of the cathode was significantly improved by a novel in-situ and self-limiting copper migration approach into the V2O5 structure. This process takes advantage of the dissolution of Cu by the ionic liquid-based electrolyte, as well as the presence of two different accommodation sites in the nanostructured V2O5 available for aluminum-ions and the migrated Cu. Furthermore, the advanced nanostructured cathode delivered a specific discharge capacity of up to ~170 mAh g−1 and the reversible intercalation of Al3+ for more than 500 cycles with a high Coulomb efficiency reaching nearly 100%. The binder-free concept results in an energy density of 74 Wh kg−1, which shows improved energy density in comparison to the so far published V2O5-based cathodes. Our results provide valuable insights for the future design and development of novel binder-free and self-supporting electrodes for rechargeable multivalent metal-ion batteries associating a high energy density, cycling stability, safety and low cost.

Enzyme-based biocatalysis exhibits multiple advantages over inorganic catalysts, including the biocompatibility and the unchallenged specificity of enzymes towards their substrate. The recovery and repeated use of enzymes is essential for any realistic application in biotechnology, but is not easily achieved with current strategies. For this purpose, enzymes are often immobilized on inorganic scaffolds, which could entail a reduction of the enzymes&rsquo, activity. Here, we show that immobilization to a nano-scaled biological scaffold, a nanonetwork of end-to-end cross-linked M13 bacteriophages, ensures high enzymatic activity and at the same time allows for the simple recovery of the enzymes. The bacteriophages have been genetically engineered to express AviTags at their ends, which permit biotinylation and their specific end-to-end self-assembly while allowing space on the major coat protein for enzyme coupling. We demonstrate that the phages form nanonetwork structures and that these so-called nanonets remain highly active even after re-using the nanonets multiple times in a flow-through reactor.

Recently, there has been growing attention and effort to search for new microbicidal drugs which present different mode of action from those already existing, as an alternative to the global threat of fungal and bacterial multi drug resistance (MDR). Here we propose biological synthesis of SnO₂ nanoparticles using mammalian cells as an economic and ecofriendly platform. This presents a novel biogenic method for SnO₂ synthesis using metal binding peptides extracted from MCF-7 human cancer cells, which induces the biomineralization of SnO₂ nanoparticles. A series of electron donor functional groups and metal binding sites in these peptides reacts with Sn

Biomaterials are used as model systems for the deposition of functional inorganic materials under mild reaction conditions where organic templates direct the deposition process. In this study, this principle was adapted for the formation of piezoelectric ZnO thin films. The influence of two different organic templates (namely, a carboxylate-terminated self-assembled monolayer and a sulfonate-terminated polyelectrolyte multilayer) on the deposition and therefore on the piezoelectric performance was investigated. While the low negative charge of the COOH-SAM is not able to support oriented attachment of the particles, the strongly negatively charged sulfonated polyelectrolyte leads to texturing of the ZnO film. This texture enables a piezoelectric performance of the material which was measured by piezoresponse force microscopy. This study shows that it is possible to tune the piezoelectric properties of ZnO by applying templates with different functionalities.

Protein-based bottom-up synthesis of functional nanomaterials and devices is one of the most promising areas in bio-nanotechnology. Here, we demonstrate that organic assemblies can serve as biologically controllable scaffolds for the deposition of inorganic nanoparticles. In this work, wild-type M13 phages were employed for controlled mineralization of zinc oxide particles. Our aim was to construct layered structures of organic and inorganic materials which contain alternating layers on a smooth substrate. The structure, elemental composition, and also the integrity of the organic and the biologically-templated inorganic layers were studied. A uniform nano-hybrid structure without significant thickness fluctuations was fabricated by using a high concentration of M13 phages and a carbon-coated substrate. The current study gives insight into the combination of organic–inorganic materials to form a multilayered structure, which in turn sets the stage for the fabrication of electronic devices, e. g. actuators or capacitors.

The usage of biomineralization processes performed by living microalgae to create 3D nanostructured materials are advantageous compared to conventional synthesis routes. Exploitation of in vivo shaping using living cells leads to inorganic intricate biominerals, produced with low environmental impact. Since biomineralization processes are genetically controlled, the formation of nanostructured materials is highly reproducible. The shells of microalgae, like coccoliths, are particularly of great interest. This study shows the generation of mesoporous highly structured functional materials with induced optoelectronical properties using in vivo processes of the microalga species Emiliania huxleyi. It demonstrates the metabolically driven incorporation of the lanthanide terbium into the coccoliths of E. huxleyi as a route for the synthesis of finely patterned photoluminescent particles by feeding the microalgae with this luminescent element. The resulting green luminescent particles have hierarchical ordered pores on the nano- and microscale and may act as powerful tools for many applications; they may serve as imaging probes for biomedical applications, or in microoptics. The luminescent coccoliths combine a unique hierarchical structure with a characteristic luminescence pattern, which make them superior to conventional produced Tb doted material. With this study, the possibility of the further exploitation of coccoliths as advanced functional materials for nanotechnological applications is given.

Carbon fibers are outstanding reinforcements for ceramic components due to their excellent creep and long-term thermochemical and thermomechanical stability. Nevertheless, these properties are dramatically downgraded if the unprotected fibers are exposed to an oxidative or corrosive environment. Thin ceramic coatings can improve the corrosion resistance and tailor the fiber/matrix interface in order to achieve optimized stress transfer and damage tolerance. The continuous liquid phase coating (CLPC) technique with subsequent pyrolysis is a promising alternative to chemical vapor deposition (CVD) processes. The possibility to deposit homogenous thin flaw-free coating layers on every filament of high tenacity carbon fiber bundles has been successfully proven in previous studies. In this work, high modulus carbon fibers were coated with different polysiloxane-based resins, and the obtained rovings were implemented in SiOC matrices by the precursor impregnation and pyrolysis (PIP) route. Thermogravimetric analysis shows an increased oxidation resistance of the coated fibers compared with reference samples. Enhanced fiber/matrix interface strength further improved the mechanical performance of the fabricated composites.

Nanobiomaterials application into tissue repair and ulcer management is experiencing its golden age due to spurring diversity of translational opportunity to clinics. Over the past years, research in clinical science has seen a dramatic increase in medicinal materials at nanoscale those significantly contributed to tissue repair. This chapter outlines the new biomaterials at nanoscale those contribute state of the art clinical practices in ulcer management and wound healing due to their superior properties over traditional dressing materials. Designing new recipes for nanobiomaterials for tissue engineering practices spanning from micro to nano-dimension provided an edge over traditional wound care materials those mimic tissue in vivo. Clinical science stepped into design of artificial skin and extracellular matrix components emulating the innate structures with higher degree of precision. Advances in materials sciences polymer chemistry have yielded an entire class of new nanobiomaterials ranging from dendrimer to novel electrospun polymer with biodegradable chemistries and controlled molecular compositions assisting wound healing adhesives, bandages and controlled of therapeutics in specialized wound care. Moreover, supportive regenerative medicine is transforming into rational, real and successful component of modern clinics providing viable cell therapy of tissue remodeling. Soft nanotechnology involving hydrogel scaffold revolutionized the wound management supplementing physicobiochemical and mechanical considerations of tissue regeneration. Moreover, this chapter also reviews the current challenges and opportunities in specialized nanobiomaterials formulations those are desirable for optimal localized wound care considering their in situ physiological microenvironment.

The coating of regular-shaped, readily available nanorod biotemplates with inorganic compounds has attracted increasing interest during recent years. The goal is an effective, bioinspired fabrication of fiber-reinforced composites and robust, miniaturized technical devices. Major challenges in the synthesis of applicable mineralized nanorods lie in selectivity and adjustability of the inorganic material deposited on the biological, rod-shaped backbones, with respect to thickness and surface profile of the resulting coating, as well as the avoidance of aggregation into extended superstructures. Nanotubular tobacco mosaic virus (TMV) templates have proved particularly suitable towards this goal: Their multivalent protein coating can be modified by high-surface-density conjugation of peptides, inducing and governing silica deposition from precursor solutions in vitro. In this study, TMV has been equipped with mineralization-directing peptides designed to yield silica coatings in a reliable and predictable manner via precipitation from tetraethoxysilane (TEOS) precursors. Three peptide groups were compared regarding their influence on silica polymerization: (i) two peptide variants with alternating basic and acidic residues, i.e. lysine–aspartic acid (KD)x motifs expected to act as charge-relay systems promoting TEOS hydrolysis and silica polymerization; (ii) a tetrahistidine-exposing polypeptide (CA4H4) known to induce silicification due to the positive charge of its clustered imidazole side chains; and (iii) two peptides with high ZnO binding affinity. Differential effects on the mineralization of the TMV surface were demonstrated, where a (KD)x charge-relay peptide (designed in this study) led to the most reproducible and selective silica deposition. A homogenous coating of the biotemplate and tight control of shell thickness were achieved.

Silicon Carbide (SiC) samples with controlled carbon contents are manufactured from polymeric precursors. Based on X-ray diffraction (XRD) data, a correlation of the excess carbon content and the crystallization kinetics of silicon carbide are determined for the obtained pyrolysates. The crystallization mechanisms as well as the corresponding activation energies EA are also determined. Furthermore, the influence of the carbon content on the oxidation behavior of these pyrolysates is studied. A model for the oxidation of the prepared silicon carbide-based materials is proposed.

The effect of redox metals such as iron and copper on multiple sclerosis and amyotrophic lateral sclerosis has been intensively studied. However, the origin of these disorders remains uncertain. This review article critically describes the physiology of redox metals that produce oxidative stress, which in turn leads to cascades of immunomodulatory alteration of neurons in multiple sclerosis and amyotrophic lateral sclerosis. Iron and copper overload has been well established in motor neurons of these diseases’ lesions. On the other hand, the role of other metals like cadmium participating indirectly in the redox cascade of neurobiological mechanism is less studied. In the second part of this review, we focus on this less conspicuous correlation between cadmium as an inactive-redox metal and multiple sclerosis and amyotrophic lateral sclerosis, providing novel treatment modalities and approaches as future prospects.

Cancer cells have the capacity to synthesize nanoparticles (NPs). The detailed mechanism of this process is not very well documented. We report the mechanism of biomineralization of aqueous gold chloride into NPs and microplates in the breast-cancer cell line MCF7. Spherical gold NPs are synthesized in these cells in the presence of serum in the culture media by the reduction of HAuCl4. In the absence of serum, the cells exhibit gold microplate formation through seed-mediate growth albeit slower reduction. The structural characteristics of the two types of NPs under different media conditions were confirmed using scanning electron microscopy (SEM); crystallinity and metallic properties were assessed with transmission electron microscopy (TEM) and x-ray photoelectron spectroscopy (XPS). Gold-reducing proteins, related to cell stress initiate the biomineralization of HAuCl4 in cells (under serum free conditions) as confirmed by infrared (IR) spectroscopy. MCF7 cells undergo irreversible replicative senescence when exposed to a high concentration of ionic gold and conversely remain in a dormant reversible quiescent state when exposed to a low gold concentration. The latter cellular state was achievable in the presence of the rho/ROCK inhibitor Y-27632. Proteomic analysis revealed consistent expression of specific proteins under serum and serum-free conditions. A high-throughput proteomic approach to screen gold-reducing proteins and peptide sequences was utilized and validated by quartz crystal microbalance with dissipation (QCM-D). Statement of significance Cancer cells are known to synthesize gold nanoparticles and microstructures, which are promising for bioimaging and other therapeutic applications. However, the detailed mechanism of such biomineralization process is not well understood yet. Herein, we demonstrate that cancer cells exposed to gold ions (grown in serum/serum-free conditions) secrete shock and stress-related proteins with specific gold-binding/reducing polypeptides. Cells undergo reversible senescence and can recover normal physiology when treated with the senescence inhibitor depending on culture condition. The use of mammalian cells as microincubators for synthesis of such particles could have potential influence on their uptake and biocompatibility. This study has important implications for in-situ reduction of ionic gold to anisotropic micro-nanostructures that could be used in-vivo clinical applications and tumor photothermal therapy.

Due to its small dimensions and high stability, tobacco mosaic virus (TMV) is used as nano-scaffold frequently. Its surface can be engineered to meet specific needs for technical, medical or materials applications. However, not all technically desirable TMV coat protein (CP) mutants can be propagated in plants successfully, if they change the efficiency of virion assembly. In order to circumvent this problem, a novel wild type (wt) CP-assisted and RNA-directed assembly procedure was designed for a recalcitrant CP mutant: Although pure hexahistidine-tagged CP cannot form particles on its own with TMV RNA in vitro, it was integrated into full-length particles if blended with wt CP in different proportions. The resulting rods formed dense monolayers with short range alignment on silicon substrates, substantially different from the largely wavy patterns obtained with wt TMV. Since they also mediated efficient ZnO deposition under mild conditions, the approach has yielded a new class of biotemplates which are amenable to the formation of nanostructured hybrid materials with adjustable texture for various applications.

The distinct electronic properties, including p-type semiconducting and a wide optical band gap, renders SnO suitable for applications such as microelectronic devices, gas sensors and electrodes. However, the synthesis of SnO is rather challenging due to the instability of the oxide, which is usually obtained as a by-product of SnO 2 fabrication. In this work, we developed a bioinspired synthesis, based on a hydrothermal approach, for the direct production of SnO nanoparticles. The amount of mineralizer, inducing the precipitation, was identified, which supports a template-free formation of the nanosized SnO particles at low temperature and mild chemical conditions. Moreover, the SnO nanoparticles exhibit a shape of unique three-dimensional crosses similar to the calcite crosses present in the calcareous sponges. We demonstrated that SnO crosses are evenly distributed and embedded in an organic scaffold by an ice-templating approach, in this way closely mimicking the structure of calcareous sponges. Such scaffolds, reinforced by an active material, here SnO, could be used as filters, sensors or electrodes, where a high surface area and good accessibility are essential. This article is part of the theme issue ‘Bioinspired materials and surfaces for green science and technology (part 2)’.

Aluminum-doped ZnO (AZO) thin films were produced via template-directed deposition at 60 °C. By adding organic molecules to the deposition solution, it is possible to control the crystallite growth, and nanocrystallinity is achieved. An organic template, 3-aminopropyltriethoxysilane (APTES), is used to direct the attachment of the crystallites on the substrate. The optical properties and the incorporation of the aluminum from solution into the ZnO films were measured using photoluminescence (PL) and inductively coupled plasma atomic emission spectroscopy (ICP-AES). The morphology of the film was investigated using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The latter revealed a preferred orientation of the crystallites in the samples where more than 15 mol% Al was added to the stock solution. For values higher than 30 mol% Al in solution, no ZnO was found at all.

International audience; The structure and properties of polymer-derived Si-(B-)O-C glasses have been shown to be significantly influenced by the boron content and pyrolysis temperature. This work determined the impact of these two parameters on the thermodynamic stability of these glasses. High-temperature oxide melt solution calorimetry was performed on a series of amorphous samples, with varying boron contents (0-7.7 at.%), obtained by pyrolysis of precursors made by a sol-gel technique. Thermodynamic analysis of the calorimetric results demonstrated that at a constant pyrolysis temperature, adding boron makes the materials energetically less stable. While the B-containing glasses pyrolyzed at 1000 degrees C were energetically less stable than the competitive crystalline components, increasing the pyrolysis temperature to 1200 degrees C led to their enthalpic stability. Si-29 and B-11 MAS nuclear magnetic resonance (NMR) spectroscopy measurements on selected samples confirmed a decrease in the concentrations of mixed Si-centered SOiC4-i and B-centered BOjC3-j bonds at the expense of formation of SiO4 and B (OSi)(3) species (indicating a tendency toward phase separation) when the boron content and pyrolysis temperature increased. In light of the findings from calorimetry and NMR spectroscopy, we propose a structure-energetic relationship in Si-(B-) O-C glasses.

The genetic engineering of M13 phage coat proteins provides an excellent system for the generation of functionalized biotemplates for the mineralization of inorganic materials in the nanometer range. Such biotemplates open facile synthesis approaches for the fabrication of miniaturized devices. The gold-binding peptide A3 was expressed at two different locations on the M13 particle surface, obtaining functionalized biotemplates with either gold-binding peptides at the one end or along the whole phage particle, respectively. The functionality of the gold-binding peptides fused to the respective phage coat proteins was tested by a binding assay with colloidal gold particles and confirmed by transmission electron microscopy. The engineered phage templates have a high affinity to gold compared with non-modified M13 phages. The binding strength is correlated to the number of expressed gold-binding peptides on the M13 phage particles. Gold nanoparticles (GNPs) were mineralized from chloroauric acid solutions. There, the M13 templates controlled the shape of the mineralized GNPs and the kinetic of the mineralization reaction. In the presence of M13 templates, GNPs were mineralized at the sites where the gold-binding peptides are localized. This approach shows a facile method for the localized mineralization of GNPs under the control of functionalized biotemplates.

Low-temperature, solution-based self-assembly of vanadia nanofibers yields a free-standing, ceramic paper with an outstanding combination of high strength, stiffness, and macroscopic flexibility. Its excellent mechanical performance results from a brick-and-mortar like architecture, which combines strong covalent bonding within the single-crystalline nanofibers with an intricate hydrogen bonding network between them.

Biomineralization in organisms is strictly regulated, and therefore, chemical compositions as well as crystal structures of the minerals are species specific. During the embryonic development, sea urchin larvae produce a calcite endoskeleton (spicules) that contains about 5% of Mg. For sea urchins and other organisms, it is assumed that Mg is important for the process of biomineralization and for the mechanical properties of the resulting biomineral. To study the influence of Mg on skeletal growth and on biomineral structure and composition, sea urchin larvae spicules were chosen as an in vivo test system. For this purpose, the Mg/Ca ratio was modified in the artificial seawater medium wherein sea urchin larvae were growing. It was shown that Mg deficiency during larval development caused morphology defects of the larvae and of their calcite spicules. The Mg distribution within the larvae skeleton was analyzed and found to be homogenous. An in vivo reduction of the Mg content influenced the mechanical performance of larval spicules (Young’s modulus and hardness). The investigations of larvae exposed to reduced Mg conditions highlight the important role Mg plays for sea urchin larvae development, biomineralization process and the resulting biomineral. The sea urchin larvae are presented as an ideal model to study different effects on larval development and morphology, especially on the biomineral properties.

The synthesis of ceramic materials combining high porosity and permeability with good mechanical stability is challenging, as optimising the latter requires compromises regarding the first two properties. Nonetheless, significant progress can be made in this direction by taking advantage of the structural design principles evolved by nature. Natural cellular solids achieve good mechanical stability via a defined hierarchical organisation of the building blocks they are composed of. Here, we report the first synthetic, ceramic-based scaffold whose architecture closely mimics that of cuttlebone –a structural biomaterial whose porosity exceeds that of most other natural cellular solids, whilst preserving an excellent mechanical strength. The nanostructured, single-component scaffold, obtained by ice-templated assembly of V2O5 nanofibres, features a highly sophisticated and elaborate architecture of equally spaced lamellas, which are regularly connected by pillars as lamella support. It displays an unprecedented porosity of 99.8 %, complemented by an enhanced mechanical stability. This novel bioinspired, functional material not only displays mechanical characteristics similar to natural cuttlebone, but the multifunctionality of the V2O5 nanofibres also renders possible applications, including catalysts, sensors and electrodes for energy storage.

Amorphous composite films, composed of a Ti1 − xVxO2 solid-solution phase and a V2O5 phase, were produced by chemical bath deposition and subsequently air-annealed at various temperatures up to 550 °C. The microstructure and chemical composition of the as-prepared and annealed films were investigated by a combinatorial experimental approach using Scanning electron microscopy, X-ray powder diffraction and X-ray photoelectron spectroscopy. Ultraviolet–Visible Spectrometry was applied to determine the optical band gap of the as-prepared and annealed films. It followed that the incorporation of vanadium in the as-deposited films reduces the optical band gap of TiO2 from about 3.8 eV to 3.2 eV. Annealing of the films up to 350 °C leads to slight increase of band gap, as attributed to a reduction of the defect density in the initially amorphous oxide films due to the gradual development of long-range order and a concurrent reduction of the V4+-dopant concentration in the Ti1 − xVxO2 solid-solution phase. The films crystallized upon annealing in air at 550 °C, which resulted in drastic changes of the phase constitution, optical absorbance and surface morphology. Due to the lower solubility of V4+ in crystalline TiO2, V4+ segregates out of the crystallizing Ti1 − xVxO2 solid-solution phase, forming crystalline V2O5 at the film surface.