Mesoporous bioactive glasses (MBGs) with a compoisition of 85SiO 2 -10CaO-5P 2 O 5 (mol %) have been prepared through the evaporation-induced self-assembly (EISA) method, using P123 as a structure directing agent. For the first time, SiO 2 -CaO-P 2 O 5 MBGs with identical composition and textural properties, but exhibiting different bicontinuous 3D-cubic and 2D-hexagonal structures, have been prepared. These materials allow us to discriminate the role of the structure on the bioactivity, from other parameters. To understand the role of each component on the mesostructure, local environment, and bioactive behavior, mesoporous 100SiO 2 , 95SiO 2 -5P 2 O 5 , and 90SiO 2 -10CaO (mol %) materials were also prepared under the same conditions. The results demonstrate that the joint presence of CaO and P 2 O 5 results in amorphous calcium phosphate (ACP) clusters sited at the pore wall surface. This heterogeneity highly improves the bioactive behavior of these materials. In addition, the presence of ACP clusters within the silica network leads to different mesoporous structures. The mesoporous order can be tuned through a rigorous control of the solvent evaporation temperature during the mesophase formation, resulting in p6mm, p6mm/Ia3d coexistence, and Ia3d phases for 20, 30, and 40°C, respectively. Preliminary results indicate that, in the case of identical composition and textural properties, the mesoporous structure does not have influence on the apatite formation, although initial ionic exchange is slightly enhanced for 3D cubic bicontinuous structures.

Multifunctional 3D nanocomposite scaffolds with the ability for loading and sustained delivery of an antimicrobial agent, to eliminate and prevent bone infection and at the same time to contribute to bone regeneration process without cytotoxic effects on the surrounding tissue has been proposed. These 3D scaffolds exhibit a sustained levofloxacin delivery at physiological pH (pH 7.4), which increasing notably when pH decreases to characteristic values of bone infection process (pH 6.7 and pH 5.5). In vitro competitive assays between preosteoblastic and bacteria onto the 3D scaffold surface demonstrated an adequate osteoblast colonization in entire scaffold surface together with the ability to eliminate bacteria contamination.

The decellularized extracellular matrix (ECM) obtained from human and porcine adipose tissue (AT) is currently used to prepare regenerative medicine bio-scaffolds. However, the influence of these natural biomaterials on host immune response is not yet deeply understood. Since macrophages play a key role in the inflammation/healing processes due to their high functional plasticity between M1 and M2 phenotypes, the evaluation of their response to decellularized ECM is mandatory. It is also necessary to analyze the immunocompetence of macrophages after contact with decellularized ECM materials to assess their functional role in a possible infection scenario. In this work, we studied the effect of four decellularized adipose matrices (DAMs) obtained from human and porcine AT by enzymatic or chemical methods on macrophage phenotypes and fungal phagocytosis. First, a thorough biochemical characterization of these biomaterials by quantification of remnant DNA, lipids, and proteins was performed, thus indicating the efficiency and reliability of both methods. The proteomic analysis evidenced that some proteins are differentially preserved depending on both the AT origin and the decellularization method employed. After exposure to the four DAMs, specific markers of M1 proinflammatory and M2 anti-inflammatory macrophages were analyzed. Porcine DAMs favor the M2 phenotype, independently of the decellularization method employed. Finally, a sensitive fungal phagocytosis assay allowed us to relate the macrophage phagocytosis capability with specific proteins differentially preserved in certain DAMs. The results obtained in this study highlight the close relationship between the ECM biochemical composition and the macrophage’s functional role.

The exfoliation and colloidal stabilization of layered transition metal dichalcogenides (TMDs) in an aqueous medium using functional biomolecules as dispersing agents have a number of potential benefits toward the production and practical use of the corresponding two-dimensional materials, but such a strategy has so far remained underexplored. Here, we report that DNA and RNA nucleotides are highly efficient dispersants in the preparation of stable aqueous suspensions of MoS and other TMD nanosheets at significant concentrations (up to 5-10 mg mL). Unlike the case of common surfactants, for which adsorption on 2D materials is generally based on weak dispersive forces, the exceptional colloidal stability of the TMD flakes was shown to rely on the presence of relatively strong, specific interactions of Lewis acid-base type between the DNA/RNA nucleotide molecules and the flakes. Moreover, the nucleotide-stabilized MoS nanosheets were shown to be efficient catalysts in the reduction of nitroarenes (4-nitrophenol and 4-nitroaniline), thus constituting an attractive alternative to the use of expensive heterogeneous catalysts based on noble metals, and exhibited an electrocatalytic activity toward the hydrogen evolution reaction that was not impaired by the possible presence of nucleotide molecules adsorbed on their active sites. The biocompatibility of these materials was also demonstrated on the basis of cell proliferation and viability assays. Overall, the present work opens new vistas on the colloidal stabilization of 2D materials based on specific interactions that could be useful toward different practical applications.

El artículo seleccionado no se encuentra disponible por ahora a texto completo por no haber sido facilitado todavía por el investigador a cargo del archivo del mismo.

Crystalline nanoparticles are very attractive building blocks for the preparation of nanostructured materials. These particles can be dispersed in different noncrystalline mesostructured matrixes in order to obtain nanocomposite systems which combine the properties of both components broadening their functionality. In the present study, a novel nanocomposite bioceramic formed by nanocrystalline apatite particles uniformly embedded into a mesostructured SiO 2 −CaO−P 2 O 5 glass wall has been synthesized through the evaporation-induced self-assembly (EISA) method, commonly used for mesoporous bioactive glass synthesis, but accelerating the sol−gel apatite crystallization rate by strong acidification. Moreover, the use of F127 surfactant as a structure directing agent in this synthesis has allowed the homogeneous nanocrystalline apatite particles incorporation inside of the amorphous mesoporous glass. In vitro bioactive assays have shown a fast apatite-like phase formation similar to that exhibited by mesoporous bioactive glasses. Furthermore, the response of L929 fibroblasts and Saos-2 osteoblasts to this new nanocomposite has indicated a significant improvement in its biocompatibility compared with conventional mesoporous bioactive glasses.

A novel nanosystem based on mesoporous silica nanoparticles covered with carbosilane dendrons grafted on their external surface is reported. This system is able to transport single oligonucleotide strands into cells, avoiding the electrostatic repulsion between the cell membrane and the negatively charged nucleic acids thanks to the cationic charge provided by the dendron coating in physiological conditions. Moreover, the presence of the highly ordered pore network inside the silica matrix would make possible to allocate other therapeutic agents within the mesopores with the aim of achieving a double delivery. First, carbosilane dendrons of second and third generation possessing ammonium or tertiary amine groups as peripheral functional groups were prepared. Hence, different strategies were tested in order to obtain their suitable grafting on the nanoparticles outer surface. As nucleic acid model, a single stranded DNA oligonucleotide tagged with a fluorescent Cy3 moiety was used to evaluate the DNA adsorption capacity. The hybrid material functionalized with the third generation of neutral dendron showed excellent DNA binding properties. Finally, the cytotoxicity as well as the capability to deliver DNA into cells, was tested in vitro using a human osteoblast-like cell line, achieving good levels of internalization of the vector DNA/carbosilane dendron functionalized material without affecting cellular viability.

No abstract