Cristalli Liquidi Elastomerici e radiazione luminosa: un nuovo approccio alla nanorobotica

Lo scopo di questo lavoro di tesi è quello di realizzare nuovi materiali che siano elastomeri liquido-cristallini e che siano in grado di rispondere con una deformazione macroscopica agli stimoli luminosi. Questo è possibile incorporando un piccolo quantitativo di molecole azobenzeniche fotosensibili all'interno di un network elastomerico liquido-cristallino. Il lavoro si è suddiviso in più fasi partendo dalla messa a punto di processi sintetici efficaci per ottenere i monomeri liquido cristallini e il dye azobenzenico; passando poi alla preparazione e valutazione di diverse miscele monomeriche e delle tecniche di allineamento dei campioni liquido cristallini; i campioni sono stati poi foto-polimerizzati per ottenere film elastomerici, dei quali è stata infine verificata la foto-responsività per confermare l'idoneità dei materiali realizzati alle applicazioni come attuatori foto-sensibili. L'indagine si è concentrata inizialmente sulla sintesi dei monomeri liquido-cristallini, cercando di mettere a punto strategie sintetiche efficienti che fornissero prodotti puri con buone rese di reazione. Tali monomeri sono stati poi caratterizzati, studiando anche le loro proprietà di cristalli liquidi con analisi DSC e osservazione al microscopio in luce polarizzata. In seguito sono stati preparati elastomeri liquido-cristallini e sono stati osservati i cambiamenti al variare del grado di reticolazione del materiale, dell'agente reticolante impiegato, dei tempi di polimerizzazione utilizzati. E' stato studiato il comportamento termico dei materiali attraverso analisi DSC e DMA e le loro proprietà ottiche con l'ausilio di un microscopio ottico polarizzatore

Metal–organic frameworks meet polymer brushes: enhanced crystalline film growth induced by macromolecular primers

We used poly-(3-sulfopropylmethacrylate) brushes as macromolecular 3D primers to promote heterogeneous nucleation and growth of archetypal ZIF-8 MOF thin films. The enhancement can be understood in terms of a high preconcentration of Zn2+ ions in the polymer brush; this leads to a rapid increase of nucleation sites in the primer.Fil: Rafti, Matias. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Allegretto, Juan Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentina. Universidad Nacional de San Martín; ArgentinaFil: Segovia, Gustavo Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentina. Universidad Nacional de San Martín; ArgentinaFil: Tuninetti, Jimena Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Giussi, Juan Martín. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Bindini, Elisa. Universite Pierre et Marie Curie; FranciaFil: Azzaroni, Omar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentin

Metal-organic frameworks meet polymer brushes: enhanced crystalline film growth induced by macromolecular primers

We used poly-(3-sulfopropylmethacrylate) brushes as macromolecular 3D primers to promote heterogeneous nucleation and growth of archetypal ZIF-8 MOF thin films. The enhancement can be understood in terms of a high preconcentration of Zn2+ ions in the polymer brush; this leads to a rapid increase of nucleation sites in the primer.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

Strontium titanate (SrTiO3) mesoporous coatings for enhanced strontium delivery and osseointegration on bone implants

The incorporation of strontium (Sr) in titania enhances surface bioactivity and has a positive effect on pre-osteoblastic cell attachment, proliferation, and differentiation. Strontium titanate mesoporous films (SrTiMFs) with 30% pore volume and a 20% Sr molar content have been prepared by the evaporation induced self-assembly method. SrTiMFs display a large internal surface area available for exchange of Sr, which is released in cell media up to 44% within the first 8 h. SrTiMFs improve attachment of MC3T3-E1 pre-osteoblastic cells, which show larger filopodia and more elongated features than cells attached to plain mesoporous titania films (MTFs). SrTiMFs also display improved cell proliferation and differentiation rates indicating that overall Sr incorporation into mesoporous titania coatings can lead to enhanced osseointegration during the early stages of bone tissue formation.Fil: Escobar, Ane. Centro de Investigación Cooperativa en Biomateriales; EspañaFil: Muzzio, Nicolás Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentina. Centro de Investigación Cooperativa en Biomateriales; EspañaFil: Angelome, Paula Cecilia. Comisión Nacional de Energía Atómica. Gerencia del Área de Seguridad Nuclear y Ambiente. Gerencia de Química (CAC); Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Bordoni, Andrea Veronica. Comisión Nacional de Energía Atómica. Gerencia del Área de Seguridad Nuclear y Ambiente. Gerencia de Química (CAC); Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Martínez, Angel. Centro de Investigación Cooperativa en Biomateriales; EspañaFil: Bindini, Elisa. Centro de Investigación Cooperativa en Biomateriales; EspañaFil: Coy, Emerson. Adam Mickiewicz University. Nanobiomedical Centre; PoloniaFil: Andreozzi, Patrizia. Centro de Investigación Cooperativa en Biomateriales; EspañaFil: Grzelczak, Marek. Donostia International Physic Center; . Basque Foundation for Science; EspañaFil: Moya, Sergio E.. Centro de Investigación Cooperativa en Biomateriales; Españ

Antibacterial mesoporous titania films with embedded gentamicin and surface modified with bone morphogenetic protein 2 to promote osseointegration in bone implants

Novel approaches are needed to avoid bacterial infections following implant surgery. Here the use of mesoporous titania films (MTFs) for gentamicin loading and delivery and the surface functionalization of MFTs with human recombinant bone morphogenetic protein 2 (hrBMP-2) are discussed. Gentamicin is incorporated into the MTF pores by immersion of the porous materials in gentamicin solution while hrBMP-2 is adsorbed on top of the MTF. Contact angle and X-ray photoelectron spectroscopy measurements are performed to prove gentamicin loading and hrBMP-2 functionalization. An initial burst release of gentamicin takes place in physiological media followed by a prolonged release that lasts weeks. Such a release profile is highly appealing for bone implants where a high concentration of antibiotics is necessary during implant surgery while a lower antibiotic concentration is needed until tissue is regenerated. The MTFs loaded with gentamicin and functionalized with hrBMP-2 are effective against Staphylococcus aureus colonization, and the presence of hrBMP-2 enhances MC3T3-E1 preosteoblastic cell attachment, proliferation, and differentiation.Fil: Escobar, Ane. Centro de Investigación Cooperativa en Biomateriales; EspañaFil: Muzzio, Nicolás Eduardo. Centro de Investigación Cooperativa en Biomateriales; España. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Coy, Emerson. Adam Mickiewicz University; PoloniaFil: Liu, Hui. Chinese Academy of Sciences; República de ChinaFil: Bindini, Elisa. Centro de Investigación Cooperativa en Biomateriales; EspañaFil: Andreozzi, Patrizia. Centro de Investigación Cooperativa en Biomateriales; EspañaFil: Wang, Guocheng. Chinese Academy of Sciences; República de ChinaFil: Angelome, Paula Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; ArgentinaFil: Delcea, Mihaela. University of Greifswald; AlemaniaFil: Grzelczak, Marek. Donostia International Physic Center; . Basque Foundation for Science; EspañaFil: Moya, Sergio E.. Centro de Investigación Cooperativa en Biomateriales; Españ

Impact of PEGylation on the degradation and pore organization in Mesoporous Silica Nanoparticles: a study of the inner mesoporous structure in physiologically relevant ionic conditions

The degradation of mesoporous silica nanoparticles (MSNs) in the biological milieu due to silica hydrolysis plays a fundamental role for the delivery of encapsulated drugs and therapeutics. However, little is known on the evolution of the pore arrangement in the MSNs in biologically relevant conditions. Small Angle X-ray scattering (SAXS) studies were performed on unmodified and PEGylated MSNs with a MCM-48 pore structure and average sizes of 140 nm, exposed to simulated body fluid solution (SBF) at pH 7.4 for different time intervals from 30 min to 24 h. Experiments were performed with silica concentrations below, at and over 0.14 mg/mL, the saturation concentration of silica in water at physiological temperature. At silica concentrations of 1 mg/mL (oversaturation), unmodified MSNs show variation in interpore distances over 6 h exposure to SBF, remaining constant thereafter. A decrease in radius of gyration is observed over the same time. Mesoporosity and radius of gyration of unmodified MSNs remain then unchanged up to 24 h. PEGylated MSNs at 1 mg/mL concentration show a broader diffraction peak but no change in the position of the peak is observed following 24 h exposure to SBF. PEGylated MSNs at 0.01 mg/mL show no diffraction peaks already after 30 min exposure to SBF, while at 0.14 mg/mL a small diffraction peak is present after 30 min exposure but disappears after 1 h.Fil: Ramirez, Maria de Los Angeles. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de San Martin. Instituto de Nanosistemas; Argentina. Basque Research and Technology Alliance. CIC biomaGUNE; EspañaFil: Bindini, Elisa. Basque Research and Technology Alliance. CIC biomaGUNE; EspañaFil: Moretti, Paolo. Università Politecnica Delle Marche; ItaliaFil: Soler Illia, Galo Juan de Avila Arturo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de San Martin. Instituto de Nanosistemas; ArgentinaFil: Amenitsch, Heinz. Graz University Of Technology.; AustriaFil: Andreozzi, Patrizia. Università degli Studi di Firenze; Italia. Basque Research and Technology Alliance. CIC biomaGUNE; EspañaFil: Ortore, Maria Grazia. Università Politecnica Delle Marche; ItaliaFil: Moya, Sergio E.. Basque Research and Technology Alliance. CIC biomaGUNE; Españ

Compréhension de la dynamique de dégradation in vivo des vecteurs thérapeutiques à base de silice mésoporeuse, étudié par ellipsométrie in situ

Dans les dernières 15 ans, la recherche biomédicale a exploré en profondeur l’utilisation de nanoparticules pour la délivrance ciblée de médicaments. Parmi plusieurs matériaux étudiés, la silice mesoporeuse représente une plateforme exceptionnelle pour ce type d’applications puisque elle est biocompatible et capable d’être chargé avec une quantité élevée de médicament, tout en étant facile à synthétiser et à fonctionnaliser .La connaissance des interactions entre nanoparticules de silice et environnement biologique est nécessaire pour concevoir des vecteurs thérapeutiques efficaces et pas toxiques. Cet étude a développé une nouvelle méthode d’analyse in situ pour suivre les interactions entre silice mesoporeuse et fluides biologiques réels (serum et sang), employant une cellule d’analyse microfluidique et l’ellipsometrie en réflexion totale interne. Nous avons ainsi réalisé le suivi dynamique de la dégradation de vecteurs models à base de silice poreuse structuré dans une solution tampon à pH physiologique et une solution concentré de protéines. Ces analyses ont permis d’évaluer l’influence de la structure poreuse, de l’adsorption de protéines sur la surface et de la vitesse du flux sur la dissolution de la silice mesoporeuse.Dans les dernières 15 ans, la recherche biomédicale a exploré en profondeur l’utilisation de nanoparticules pour la délivrance ciblée de médicaments. Parmi plusieurs matériaux étudiés, la silice mésoporeuse représente une plateforme exceptionnelle pour ce type d’applications puisque elle est biocompatible et capable d’être chargé avec une quantité élevée de médicament, tout en étant facile à synthétiser et à fonctionnaliser. La connaissance des interactions entre nanoparticules de silice et environnement biologique est nécessaire pour concevoir des vecteurs thérapeutiques efficaces et pas toxiques. Cet étude a développé une nouvelle méthode d’analyse in situ pour suivre les interactions entre silice mésoporeuse et fluides biologiques réels (sérum et sang), employant une cellule d’analyse microfluidique et l’ellipsométrie en réflexion totale interne. Nous avons ainsi réalisé le suivi dynamique de la dégradation de vecteurs models à base de silice poreuse structuré dans une solution tampon à pH physiologique et une solution concentré de protéines. Ces analyses ont permis d’évaluer l’influence de la structure poreuse, de l’adsorption de protéines sur la surface et de la vitesse du flux sur la dissolution de la silice mésoporeuse

The Critical Role of the Atmosphere in Dip-Coating Process

International audienceDip-coating is a common liquid deposition technique employed in research, but also for industrial production, to obtain polymer, hybrid and inorganic thin layers of controlled thickness. During liquid deposition, the substrate withdrawal speed allows in principle an easy tuning of deposited film thickness (first modeled by Landau and Levich). Yet, experimentally, unexplained thickness irreproducibility or strong fluctuations of the sol-gel films are often observed when coating large substrates, which is a critical issue for optical coatings such as anti-reflective/reflective coatings. In this study, we pointed out for the first time that uncontrolled solvent relative pressure gradients (coming from solvent evaporation) are responsible for these thickness fluctuation issues. We investigated and quantified their impact for various solutions (of sol-gel or polymer), and pointed out that the solvent evaporation rate is not constant but strongly depends on the geometric configuration of the dip-coating experiment. From this understanding, we demonstrated how an accurate tuning of processing atmosphere can provide a very good control on layer thickness in the practical case of the deposition of anti-reflective water repellent coating. In a second example, we used this phenomenon for developing a very easy synthesis strategy leading to giant and controlled thickness gradient profiles

Mind the Gap! Tailoring Sol-gel Ceramic Mesoporous Coatings on Labile Metal-organic Frameworks through Kinetic Control.

Surface engineering of metal-organic frameworks (MOFs) with a mesoporous silica coating can improve MOF mechanical properties and provide an easy way to decorate MOF nanoparticles with organic or biological molecules though silane chemistry or electrostatic interactions, while retaining open access to MOF porosity. Silica coating would be highly beneficial for employing MOFs in a wide range of applications such as catalysis or drug delivery. However, obtaining a stable, controlled core-shell structure using MOF nanoparticles as seed is challenging because of their intrinsic chemically labile nature. Here we analyze the factors that destabilize the core of the Zeolitic Imidazolate Framework-8 (ZIF-8) MOFs during the sol-gel deposition of a mesoporous silica shell causing a partial or total etching of the MOF material. Silicates in solution are found to scavenge Zn2+ ions removing them from the ZIF structure and causing a partial or complete dissolution of the ZIF seed. By carefully tuning the silicate concentration in solution simultaneous control can be obtained over both the ZIF-8 dissolution and the silica condensation kinetics, resulting in the growth of a uniform mesoporous silica shell while preserving the integrity of ZIF-8. The core-shell nanoparticles obtained show a compact core shell structure with no gap between the MOF core and the silica shell, even after calcination, while the crystalline ZIF-8 structure is retained. Overall, a general synthetic approach is presented for producing nanocomposite core-shell materials which can be applied to other MOF labile seed to design new hierarchical materials

In Vivo Tracking of the Degradation of Mesoporous Silica through 89Zr Radio-Labeled Core–Shell Nanoparticles

While mesoporous silica nanoparticles (MSNs) are extensively studied as high-potential drug delivery platforms, the successful clinical translation of these nanocarriers strongly depends on their biodistribution, biodegradation, and elimination patterns in vivo. Here, a novel method is reported to follow the in vivo degradation of MSNs by tracking a radioactive label embedded in the silica structure. Core–shell silica nanoparticles (NPs) with a dense core and a mesoporous shell are labeled with low quantities of the positron emitter 89Zr, either in the dense core or in the mesoporous shell. In vivo positron emission tomography imaging and ex vivo organ measurements reveal a remarkable difference in the 89Zr biodistribution between the shell-labeled and the core-labeled NPs. Release of the radiotracer from shell-labeled NPs is used as a probe of the extent of silica dissolution, and a prompt release of the radioisotope is observed, with partial excretion already in the first 2 h post injection, and a slower accumulation in bones over time. On the other hand, when 89Zr is embedded in the nanoparticle core, the biodistribution remains largely unchanged during the first 6 h. These findings indicate that MSNs have fast, hour-scale, degradation kinetics in vivo.Fil: Bindini, Elisa. No especifíca;Fil: Ramirez, Maria de Los Angeles. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Rios, Xabier. No especifíca;Fil: Cossío, Unai. No especifíca;Fil: Simó, Cristina. No especifíca;Fil: Gomez Vallejo, Vanessa. No especifíca;Fil: Soler Illia, Galo Juan de Avila Arturo. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Llop, Jordi. No especifíca;Fil: Moya, Sergio E.. No especifíca