Time-resolved near-infrared and two-dimensional near-infrared correlation spectroscopic studies of the polymerization process of silane coupling agents. Dynamic behavior of water molecules in the 3-aminopropyltriethoxysilane-ethanol-water system

Improved cell adhesion to activated vapor silanization-biofunctionalized Ti-6Al-4V surfaces with ECM-derived oligopeptides

Titanium implants are widely used in traumatology and various orthopedic fields. Titanium and other metallic-based implants have limited structural and functional integration into the body, which translates into progressive prosthesis instability and the need for new surgical interventions that have enormous social and economic impacts. To enhance the biocompatibility of titanium implants, numerous biofunctionalization strategies have been developed. However, the problem persists, as more than 70% of implant failures are due to aseptic loosening. In this study we addressed the problem of improving the physiological engraftability and acceptability of titanium-based implants by applying a robust and versatile functionalization method based on the covalent immobilization of extracellular matrix (ECM)-derived oligopeptides on Ti-6Al-4V surfaces treated by activated vapor silanization (AVS). The feasibility of this technique was evaluated with two oligopeptides of different structures and compositions. These oligopeptides were immobilized on Ti-6Al-4V substrates by a combination of AVS and N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride/N-hydroxysuccinimide (EDC/NHS) crosslinking chemistry. The immobilization was shown to be stable and resistant to chemical denaturing upon sodium dodecyl sulfate treatment. On Ti-6Al-4V surfaces both peptides increased the attachment, spreading, rearrangement and directional growth of mesenchymal stem and progenitor cells (MSC) with chondro- and osteo-regenerative capacities. We also found that this biofunctionalization method (AVS-EDC/NHS) increased the attachment capacity of an immortalized cell line of neural origin with poor adhesive properties, highlighting the versatility and robustness of this method in terms of potential oligopeptides that may be used, and cell lineages whose anchorage to the biomaterial may be enhanced. Collectively, this novel functionalization strategy can accelerate the development of advanced peptide-functionalized metallic surfaces, which, in combination with host or exogenously implanted stem cells, have the potential to positively affect the osteoregenerative and osteointegrative abilities of metallic-based prostheses.

Fundamental Insights into the Covalent Silane Functionalization of NiFe Layered Double Hydroxides

Layered double hydroxides (LDHs) are a class of 2D anionic materials exhibiting wide chemical versatility and promising applications in different fields, ranging from catalysis to energy storage and conversion. However, the covalent chemistry of this kind of 2D materials is still barely explored. Herein, the covalent functionalization with silanes of a magnetic NiFe-LDH is reported. The synthetic route consists of a topochemical approach followed by anion exchange reaction with surfactant molecules prior to covalent functionalization with the (3-aminopropyl)triethoxysilane (APTES) molecules. The functionalized NiFe-APTES was fully characterized by X-ray diffraction, infrared spectroscopy, electron microscopy, thermogravimetric analysis coupled with mass spectrometry and ²⁹ Si solid-state nuclear magnetic resonance, among others. The effect on the electronic properties of the functionalized LDH was investigated by a magnetic study in combination with Mössbauer spectroscopy. Moreover, the reversibility of the silane-functionalization at basic pH was demonstrated, and the quality of the resulting LDH was proven by studying the electrochemical performance in the oxygen evolution reaction in basic media. Furthermore, the anion exchange capability for the NiFe-APTES was tested employing Cr^VI , resulting in an increase of 200 % of the anion retention. This report allows for a new degree of tunability of LDHs, opening the door to the synthesis of new hybrid architectures and materials.

In situ synthesis and characterization of silver/polymer nanocomposites by thermal cationic polymerization processes at room temperature: initiating systems based on organosilanes and starch nanocrystals

New methods for the preparation of silver nanoparticles/polymer nanocomposite materials by thermal cationic polymerization of ε-caprolactone (ε-CL) or α-pinene oxide (α-PO) at room temperature (RT) and under air were developed. The new initiating systems were based on silanes (Si), starch nanocrystals (StN) and metal salts. Excellent polymerization profiles were revealed. It was shown that silver nanoparticles (Ag(0) NPs) were in situ formed and that the addition of StN improves the polymerization efficiency. The as-synthesized nanocomposite materials contained spherical nanoparticles homogeneously dispersed in the polymer matrices. Polymers and nanoparticles were characterized by gel permeation chromatography (GPC), X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and UV-vis spectroscopy. A coherent picture of the involved chemical mechanisms is presented.

PRODUCTION AND BIOFUNCTIONALIZATION OF MAGNETIC NANOBEADS FOR MAGNETIC SEPARATION OF MESSENGER RNA

The synthesis of nanosized beads of superparamagnetic iron oxide nanoparticles coated with 3-(aminopropyl)triethoxysilane is reported in this paper. The resulting beads are agglomerates of SPIONs with an open fractal like structure. These beads have been examined by means of transmission electron microscopy (TEM), photon correlation spectroscopy (PCS), and attenuated total reflection Fourier transformation infrared spectroscopy (ATR-FTIR). The resulting beads with a size of 88 nm have been further biofunctionalized with avidin and biotinylated oligo(dT).

Attachment of 3-(Aminopropyl)triethoxysilane on silicon oxide surfaces: dependence on solution temperature

Parameters important to the self-assembly of 3-(aminopropyl)triethoxysilane (APTES) on chemically grown silicon oxide (SiO 2) to form an aminopropyl silane (APS) film have been investigated using in situ infrared (IR) absorption spectroscopy. Preannealing to approximately 70 degrees C produces significant improvements in the quality of the film: the APS film is denser, and the Si-O-Si bonds between the molecules and the SiO 2 surface are more structured and ordered with only a limited number of remaining unreacted ethoxy groups. In contrast, post-annealing the functionalized SiO 2 samples after room temperature reaction with APTES (i.e., ex situ annealing) does not lead to any spectral change, suggesting that post-annealing has no strong effect on the horizontal polymerization as suggested earlier. Both IR and ellipsometry data show that the higher the solution temperature, the denser and thinner the APS layer is for a given immersion time. Finally, the APS layer obtained by preannealing the solution at 70 degrees C exhibits a better stability in deionized water than the APS layer prepared at room temperature.

Hybrid titania–aminosilane platforms evaluated with human mesenchymal stem cells

The properties of hybrid aminopropyltriethoxysilane-tetraisopropylorthotitanate (APTS-TIPT) platforms prepared by a sol-gel route have been explored, and their biocompatibility was assayed after culture of human mesenchymal stem cells (hMSCs). The organic content of this material was observed to be preferably surface-oriented as indicated by microanalytical techniques. Furthermore, the surface showed characteristic amino-silane bands when explored by Raman spectroscopy as well as indications of silane and titanate condensation. Surface activity of the amino groups was probed by ultraviolet-visible spectroscopy imine derivatization and chemical force spectroscopy, showing a pH-dependent surface charge-induced potential. hMSCs cultured onto these surfaces showed relevant differences with respect to their behavior on gelatin-coated glass plates. Even if with a lower proliferative rate than controls, the cells develop long cytosolic prolongations in osteogenic differentiation medium, thus, supporting the idea of an APTS-TIPT stimulated process.