Valeria Verdinelli

Enhancing CaP Biomimetic Growth on TiO2 Cuboids Nanoparticles via Highly Reactive Facets

Pure decahedral anatase TiO(2) particles with high content of reactive {001} facets were obtained from titanium(IV) tetrachloride (TiCl(4)) using a microemulsions droplet system at specific conditions as chemical microreactor. The product was systematically characterized by X-ray diffraction, field-emission scanning and transmission electron microscopy (FE-SEM, TEM), N(2) adsorption-desorption isotherms, FT-IR and UV-vis spectroscopy, and photoluminescence studies. The obtained cuboids around 90 nm in size have a uniform and dense surface morphology with a BET specific surface area of 11.91 m(2) g(-1) and a band gap energy (3.18 eV) slightly inferior to the anatase dominated by the less-reactive {101} surface (3.20 eV). The presence of reactive facets on titania anatase favors the biomimetic growth of amorphous tricalcium phosphate after the first day of immersion in simulated human plasma. The results presented here can facilitate and improve the integration of anchored implants and enhance the biological responses to the soft tissues.

Mimicking Natural Fibrous Structures of Opals by Means of a Microemulsion-Mediated Hydrothermal Method

Silica-based nanomaterials are of great interest because of their potential applications in constructing electronic and optoelectronic nanodevices. Especially significant are those that combine the properties of photonic crystal with a fibrous semiconductor structure. Here we report the use of microemulsion droplet systems as a simple and controllable route for the synthesis of 3D opals materials with an unusual fibrous microstructure similar to those that exist in nature. By this method, we demonstrate the creation of very long fibrils of 30-50 nm diameter and more than 20 μm length showing simultaneous short and long wavelength light emissions and band gap values (5.50 and 4.41 eV) comparable to those obtained for silicon-based metal oxide semiconductors.

Role of interfacial elasticity of microemulsions on the morphology of TiO2 nanostructures: stiff templates versus flexible templates

The effects of temperature and interfacial elasticity on nanostructured titanium dioxide (TiO2) microemulsions templated materials have been investigated. The aim was to establish a simple and rapid selection of the best experimental conditions for achieving some required material property. TiO2 materials have been prepared through reactive microemulsion precipitation. The effect of microemulsion process parameters (temperature and oil phase density) on the final material characteristics has been investigated. The titania nanopowders were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, and N2 adsorption–desorption isotherms. The results obtained by different process conditions show that the nonpolar phase density and temperature of microemulsions have a great influence on the final characteristics of the obtained material. A reduction of the microemulsion oil density causes a significant decrease in the particle agglomeration and an augment of the material-specific surface area and pore volume. At the same time, rutile is favored over anatase phase. The increase of template microemulsion temperature produces, in some systems, a morphology change from granular to a bicontinuous structure.

Assessing structure and dynamics of fibrinogen films on silicon nanofibers: towards hemocompatibility devices

An enhanced knowledge of the interaction of proteins with the surfaces of implantable materials, particularly regarding fibrinogen (Fb), is fundamental for understanding cellular events and the overall host response. Thinking of future use of Si-nanofibers as three-dimensional (3D) scaffolds for construction of implantable artificial devices, the correlation among the material surface characteristics and the amount, structure and distribution of adsorbed Fb molecules are analyzed. The Fb adsorption process occurs in a stepwise fashion with an initial rapid adsorption, an intermediate reorganization and finally a second slower adsorption regime over a longer period of time. There is a partial desorption of the protein after the first adsorption process, which demonstrates that this step is reversible until 2 × 104 s. Nevertheless the whole process is irreversible, with a high distortion of the original material morphology. The limiting value for the adsorbed Fb surface concentration is about 270 ± 20 μg dm−2; more than three times the adsorption capacity of non fibrillar, 2D or 3D, scaffolds. The fibrous structure and the similitude in size between the substrate (d = 30–50 nm) and the Fb molecules (47–50 nm) are proposed to be the key to the enhanced adsorption process and the acquired final topography of the material.

Biomimetic formation of crystalline bone-like apatite layers on spongy materials templated by bile salts aggregates

Since the trabecular bone exhibit sponge-like bicontinuity there is a growing interest in the synthesis of spongy-like sieves for the construction of bio-active implantable materials. Here, we propose a one step sol–gel method for the synthesis of bicontinuous pore silica materials using different bile salts aqueous mixtures as templates. The influences of the type and amount of bile salt on the synthesis processes are investigated and correlated with the final material morphology. As a final point, their structural properties are interrelated with their ability to induce a bone-like apatite layer in contact with simulated body fluid (SBF). We have confirmed that under specific template conditions, the synthesized material has an open bio-active macropore structure that is blanched in a 3D-disordered sponge-like network similar than those existed in trabecular bone.

Inversion Properties of n-Alkane Phosphonic Acids Stabilized Emulsions: HLB Dependence

The emulsifier properties of n-alkane phosphonic acids (C10H21PO3H2; C12H25PO3H2 and C13H27PO3H2) and their mono- and di-sodic salts were studied, with emphasis on the morphological and dynamical inversion properties as a function of their neutralization degree. Maximum stabilization properties were appreciated for C10PO3H2 and C12PO3H2 while not for C13PO3H2. Such fact is associated to their odd number of carbon atoms chain, which is the origin of the intrachain constraints on the tail-chain flexibility.