Internal surface modification of additively manufactured macroporous TiAl6V4 biomimetic implants via a calciothermic reaction-based process and osteogenic in vivo responses.

Three-dimensional macroporous titanium-aluminum-vanadium (TiAl6V4) implants produced by additive manufacturing (AM) can be grit blasted (GB) to yield microtextured exterior surfaces, with additional micro/nano-scale surface features provided by subsequent acid etching (AE). However, the line-of-sight nature of GB causes the topography of exterior GB + AE-modified surfaces to differ from internal GB-inaccessible surfaces. Previous in vitro studies using dense TiAl6V4 substrates indicated that a nonline-of-sight, calciothermic-reaction (CaR)-based process provided homogeneous osteogenic nanotextures on GB + AE surfaces, suggesting it could be used to achieve a homogeneous nanotopography on external and internal surfaces of macroporous AM constructs.

Tailoring of TiAl6V4 Surface Nanostructure for Enhanced In Vitro Osteoblast Response via Gas/Solid (Non-Line-of-Sight) Oxidation/Reduction Reactions.

An aging global population is accelerating the need for better, longer-lasting orthopaedic and dental implants. Additive manufacturing can provide patient-specific, titanium-alloy-based implants with tailored, three-dimensional, bone-like architecture. Studies using two-dimensional substrates have demonstrated that osteoblastic differentiation of bone marrow stromal cells (MSCs) is enhanced on surfaces possessing hierarchical macro/micro/nano-scale roughness that mimics the topography of osteoclast resorption pits on the bone surface.

Individually Dispersed Gold Nanoshell-Bearing Cellulose Nanocrystals with Tailorable Plasmon Resonance.

Cellulose nanocrystals (CNCs) can be attractive templates for the generation of functional inorganic/organic nanoparticles, given their fine sizes, aspect ratios, and sustainable worldwide availability in abundant quantities. Here, we present for the first time a scalable, surfactant-free, tailorable wet chemical process for converting commercially available CNCs into individual aspected gold nanoshell-bearing particles with tunable surface plasmon resonance bands. Using a rational cellulose functionalization approach, stable suspensions of positively charged CNCs have been generated.

Tunable multimodal adhesion of 3D, nanocrystalline CoFeO pollen replicas.

3D replicas of sunflower pollen microparticles, comprised of a multicomponent magnetic spinel ferrite (CoFeO) with tailorable adhesive properties, have been synthesized for the first time via a conformal layer-by-layer (LbL) surface sol-gel (SSG) deposition process followed by organic pyrolysis and oxide compound formation at a peak temperature of 600 °C-900 °C. These high-fidelity ferrite pollen replicas exhibited multimodal (van der Waals, vdW, and magnetic) adhesion that could be tuned via control of the CoFeO nanoparticle and crystal sizes. The CoFeO pollen replicas exhibited a non-monotonic change in short-range (~10 nm) vdW adhesion with an increase in the peak firing temperature, which was consistent with the counteracting effects of particle coarsening on the size and number of nanoparticles present on the sharp tips of the echini (spines) on the pollen replica surfaces.

Surface modification of bulk titanium substrates for biomedical applications via low-temperature microwave hydrothermal oxidation.

Micro-to-nanoscale surface topographies of orthopaedic and dental implants can affect fluid wetting and biological response. Nanoscale features can be superimposed on microscale roughness of titanium (Ti) surfaces at high temperatures, resulting in increased osteoblast differentiation. However, high temperatures can compromise mechanical properties of the bulk material.

Compartmentalisation of enzymes for cascade reactions through biomimetic layer-by-layer mineralization.

Cellular metabolic pathways are paradigms for the rapid and waste-free conversion of molecules into useful products through multiple enzyme-catalyzed steps (cascade reactions). Attempts to establish efficient cascade reactions for technological applications have focused on mimicking nature's high degree of organization by controlling the positioning of enzymes through immobilization in tailor-made compartments. The present work utilized peptide-mediated layer-by-layer mineralization as a facile and generic method for the compartmentalisation of multi-enzyme systems in nanoscale silica layers.

Superposition of nanostructures on microrough titanium-aluminum-vanadium alloy surfaces results in an altered integrin expression profile in osteoblasts.

Recent studies of new surface modifications that superimpose well-defined nanostructures on microrough implants, thereby mimicking the hierarchical complexity of native bone, report synergistically enhanced osteoblast maturation and local factor production at the protein level compared to growth on surfaces that are smooth, nanorough, or microrough. Whether the complex micro/nanorough surfaces enhance the osteogenic response by triggering similar patterns of integrin receptors and their associated signaling pathways as with well-established microrough surfaces, is not well understood. Human osteoblasts (hOBs) were cultured until confluent for gene expression studies on tissue culture polystyrene (TCPS) or on titanium alloy (Ti6Al4V) disks with different surface topographies: smooth, nanorough, microrough, and micro/nanorough surfaces.

Composition optimization of scintillating rare-earth nanocrystals in oxide glass-ceramics for radiation spectroscopy.

Glass-ceramic nanocomposites comprising GdBr₃/CeBr₃ loaded sodium-aluminosilicate glasses in which scintillating crystallites are precipitated in situ from a host glass matrix were studied. This materials system shows promise as an alternative to single-crystal scintillators, with potential to be fabricated into a wide variety of sizes, shapes, and compositions. Batch compositions containing 15-18 mol.

Role of α2β1 integrins in mediating cell shape on microtextured titanium surfaces.

Surface microroughness plays an important role in determining osteoblast behavior on titanium. Previous studies have shown that osteoblast differentiation on microtextured titanium substrates is dependent on alpha-2 beta-1 (α2β1) integrin signaling. This study used focused ion beam milling and scanning electron microscopy, combined with three-dimensional image reconstruction, to investigate early interactions of individual cells with their substrate and the role of integrin α2β1 in determining cell shape.

High thermal conductivity of chain-oriented amorphous polythiophene.

Polymers are usually considered thermal insulators, because the amorphous arrangement of the molecular chains reduces the mean free path of heat-conducting phonons. The most common method to increase thermal conductivity is to draw polymeric fibres, which increases chain alignment and crystallinity, but creates a material that currently has limited thermal applications. Here we show that pure polythiophene nanofibres can have a thermal conductivity up to ∼ 4.

A magnesiothermic reaction process for the scalable production of mesoporous silicon for rechargeable lithium batteries.

Mesoporous, 3-D, nanocrystalline Si has been synthesized via the magnesiothermic reduction of SiO particles at a peak temperature of only 500 °C in a scalable flow-through reactor setup. Such 3-D porous Si as an anode material exhibited high, reversible capacities (i.e.

High-energy-density sol-gel thin film based on neat 2-cyanoethyltrimethoxysilane.

Hybrid organic-inorganic sol-gel dielectric thin films from a neat 2-cyanoethyltrimethoxysilane (CNETMS) precursor have been fabricated and their permittivity, dielectric strength, and energy density characterized. CNETMS sol-gel films possess compact, polar cyanoethyl groups and exhibit a relative permittivity of 20 at 1 kHz and breakdown strengths ranging from 650 V/μm to 250 V/μm for film thicknesses of 1.3 to 3.

The roles of titanium surface micro/nanotopography and wettability on the differential response of human osteoblast lineage cells.

Surface micro- and nanostructural modifications of dental and orthopedic implants have shown promising in vitro, in vivo and clinical results. Surface wettability has also been suggested to play an important role in osteoblast differentiation and osseointegration. However, the available techniques to measure surface wettability are not reliable on clinically relevant, rough surfaces.

Differential responses of osteoblast lineage cells to nanotopographically-modified, microroughened titanium-aluminum-vanadium alloy surfaces.

Surface structural modifications at the micrometer and nanometer scales have driven improved success rates of dental and orthopaedic implants by mimicking the hierarchical structure of bone. However, how initial osteoblast-lineage cells populating an implant surface respond to different hierarchical surface topographical cues remains to be elucidated, with bone marrow mesenchymal stem cells (MSCs) or immature osteoblasts as possible initial colonizers. Here we show that in the absence of any exogenous soluble factors, osteoblastic maturation of primary human osteoblasts (HOBs) but not osteoblastic differentiation of MSCs is strongly influenced by nanostructures superimposed onto a microrough Ti6Al4V (TiAlV) alloy.

Direct fabrication of arbitrary-shaped ferroelectric nanostructures on plastic, glass, and silicon substrates.

A complementary metal-oxide-semico-nductor (CMOS)-compatible method for the direct fabrication of arbitrary-shaped Pb(Zr0.52 Ti0.48)O3 and PbTiO3 ferroelectric/piezoelectric nanostructures on plastic, silicon, and soda-lime glass substrates is reported.

The effects of combined micron-/submicron-scale surface roughness and nanoscale features on cell proliferation and differentiation.

Titanium (Ti) osseointegration is critical for the success of dental and orthopedic implants. Previous studies have shown that surface roughness at the micro- and submicro-scales promotes osseointegration by enhancing osteoblast differentiation and local factor production. Only relatively recently have the effects of nanoscale roughness on cell response been considered.

Inverted polymer solar cells with amorphous indium zinc oxide as the electron-collecting electrode.

We report on the fabrication and performance of polymer-based inverted solar cells utilizing amorphous indium zinc oxide (a-IZO) as the electron-collecting electrode. Amorphous IZO films of 200 nm thickness were deposited by room temperature sputtering in a high-purity argon atmosphere. The films possessed a high optical transmittance in the visible region (≥ 80%), a low resistivity (3.

Assembly of large-area, highly ordered, crack-free inverse opal films.

Whereas considerable interest exists in self-assembly of well-ordered, porous "inverse opal" structures for optical, electronic, and (bio)chemical applications, uncontrolled defect formation has limited the scale-up and practicality of such approaches. Here we demonstrate a new method for assembling highly ordered, crack-free inverse opal films over a centimeter scale. Multilayered composite colloidal crystal films have been generated via evaporative deposition of polymeric colloidal spheres suspended within a hydrolyzed silicate sol-gel precursor solution.

A gas-tight Cu K alpha x-ray transparent reaction chamber for high-temperature x-ray diffraction analyses of halide gas/solid reactions.

An externally heated, x-ray transparent reaction chamber has been developed to enable the dynamic high temperature x-ray diffraction (HTXRD) analysis of a gas/solid [TiF(4)(g)/SiO(2)(s)] reaction involving a halide gas reactant formed at elevated temperatures (up to 350 degrees C) from a condensed source (TiF(4) powder) sealed within the chamber. The reaction chamber possessed x-ray transparent windows comprised of a thin (13 microm) internal layer of Al foil and a thicker (125 microm) external Kapton film. After sealing the SiO(2) specimens (diatom frustules or Stober spheres) above TiF(4) powder within the reaction chamber, the chamber was heated to a temperature in the range of 160-350 degrees C to allow for internal generation of TiF(4)(g).

Rapid bioenabled formation of ferroelectric BaTiO3 at room temperature from an aqueous salt solution at near neutral pH.

A 12-mer peptide, identified through phage display biopanning, has been used for the first time to induce the rapid formation of ferroelectric (tetragonal) nanocrystalline BaTiO3 at room temperature from an aqueous salt precursor solution at near neutral pH. BaTiO3 is widely used in capacitors, thermistors, displays, and sensors owing to its attractive dielectric, ferroelectric, pyroelectric, optical, and electrochemical properties. Two 12-mer peptides (BT1 and BT2) were selected from a phage-displayed peptide library via binding to tetragonal BaTiO3 powder.

Chemical reduction of three-dimensional silica micro-assemblies into microporous silicon replicas.

The carbothermal reduction of silica into silicon requires the use of temperatures well above the silicon melting point (> or =2,000 degrees C). Solid silicon has recently been generated directly from silica at much lower temperatures (< or =850 degrees C) via electrochemical reduction in molten salts. However, the silicon products of such electrochemical reduction did not retain the microscale morphology of the starting silica reactants.