Evaluation of the sterilization effect on biphasic scaffold based on bioactive glass and polymer honeycomb membrane

The sterilization is a core preoccupation when it comes to implantable biomaterials. The most common in industry is the gamma sterilization; however, the radiation used in this method can induce modifications in the material properties. This study investigates the impact of such radiations on the physicochemical properties and biological toxicity of a new biomaterial based on a poly-l-co-d,l-lactide polymer honeycomb membrane and bioactive glass (BG), combined, to form an assembly (membrane/BG assembly). The investigated BGs are the S53P4, which is FDA approved and clinically used, and 13-93B20, a BG containing boron promising for bone regeneration. Infrared and photoluminescence measurements revealed that, upon irradiation, defects are created in the BGs molecular matrix. Defects were identified to be mainly non-bridging oxygen hole center and occur in higher proportion in the 13-93B20 making it more sensitive to irradiation compared to the S53P4. However, the irradiation does not significantly impact the structure of the BGs. On the membrane side, the molecular weight is divided by two resulting in a lower shear stress resistance. However, the membrane honeycomb topography does not seem to be impacted by the irradiation. In contact with cells, no toxicity effect was observed, and BGs keep their bioactive properties by releasing ions beneficial to the cell fate and with no influence on apatite precipitation speed. Overall, this study showed that, despite some impact on the physicochemical properties, the irradiation does not induce deleterious effect on the membrane/BG assemblies and is therefore a suitable method for the sterilization of this novel biomaterial.Peer reviewe

TP53 mutations predict disease control in metastatic colorectal cancer treated with cetuximab-based chemotherapy

Recent studies have suggested that activation of the EGFR pathway leads to malignant transformation only if the p53 protein is inactivated. Therefore, we evaluated the impact of TP53 mutations on cetuximab-based chemotherapy (CT) sensitivity in combination with KRAS mutations that have been associated with cetuximab resistance. KRAS and TP53 status were assessed in tumours from 64 metastatic colorectal cancer patients treated with cetuximab-based CT and correlated to clinical response using the Fisher's exact test. Times to progression (TTPs) according to gene status were calculated using the Kaplan–Meier method and compared with log-rank test. TP53 mutations were found in 41 patients and were significantly associated with controlled disease (CD), as defined as complete response, partial response or stable disease (P=0.037) and higher TTP (20 vs 12 weeks, P=0.004). Remarkably, in the subgroup of 46 patients without KRAS mutation, but not in patients with KRAS mutation, TP53 mutations were also associated with CD (P=0.008) and higher TTP (24 vs 12 weeks, P=0.0007). This study suggests that TP53 mutations are predictive of cetuximab sensitivity, particularly in patients without KRAS mutation, and that TP53 genotyping could have a clinical interest to select patients who should benefit from cetuximab-based CT

Porous chitosan-silica hybrid microspheres as potential catalyst

International audienc

Porous chitosan-silica hybrid microspheres as potential catalyst

International audienc

Design of Magnetic Gelatine/Silica Nanocomposites by Nanoemulsification: Encapsulation versus in Situ Growth of Iron Oxide Colloids

International audienceThe design of magnetic nanoparticles by incorporation of iron oxide colloids within gelatine/silica hybrid nanoparticles has been performed for the first time through a nanoemulsion route using the encapsulation of pre-formed magnetite nanocrystals and the in situ precipitation of ferrous/ferric ions. The first method leads to bi-continuous hybrid nanocomposites containing a limited amount of well-dispersed magnetite colloids. In contrast, the second approach allows the formation of gelatine-silica core-shell nanostructures incorporating larger amounts of agglomerated iron oxide colloids. Both magnetic nanocomposites exhibit similar superparamagnetic behaviors. Whereas nanocomposites obtained via an in situ approach show a strong tendency to aggregate in solution, the OPEN ACCESS Nanomaterials 2014, 4 613 encapsulation route allows further surface modification of the magnetic nanocomposites, leading to quaternary gold/iron oxide/silica/gelatine nanoparticles. Hence, such a first-time rational combination of nano-emulsion, nanocrystallization and sol-gel chemistry allows the elaboration of multi-component functional nanomaterials. This constitutes a step forward in the design of more complex bio-nanoplatforms

CHARACTERIZATION OF THE EFFECT OF HEAT ON VEGETABLE TANNED LEATHER

International audienceFunded by the LabEx PATRIMA, this project combines the expertise of the CRCC laboratory, in physical chemistry and the ERRMECe laboratory in biology and biochemistry. The research aims to develop a new restoration approach for leather having lost its flexibility as a result of alteration, in particular after exposure to heat. This innovative method relies on the use of biological molecules to respect the nature of the object and preserve its past and future.Our hypothesis is that exposure to heat causes a protein aggregation. To validate this hypothesis and develop the restoration method, the modifications taking place in the leather structure are examined at different scales

CHARACTERIZATION OF THE EFFECT OF HEAT ON VEGETABLE TANNED LEATHER AND RESTORATION TRIALS THROUGH ENZYMATIC PROCESSES

International audienceThe research aims to develop a new restoration approach for leather in cultural heritage having lost its flexibility after exposure to heat. This innovative method relies on the use of biological molecules in order to respect the nature of the object and preserve its past and future. To confirm the protein aggregation expected after exposure to heat, the leather was first characterized by different techniques; then the innovative restoration approach was tested.The characterization of heat-damaged leather was performed by both physico-chemical (DMA, TGA, contact angle measurement, SEM) and biochemical (Protein extraction, Protein assays, Western-Blot) methods.Heat induces darkening, mass loss, shrinkage, stiffness increase and renders leather non wettable. Part of these changes can be due to an aggregation of leather proteins as a result of heat exposure as also shown by sequential protein extraction. Thanks to this new information, a biochemical restoration approach using enzymatic hydrolases aiming to break the protein aggregates has been developed. One of the challenges was to provide water for the enzyme without wetting the leather surface so to avoid further damage of the leather. Several procedures were tested and compared, and encouraging results were obtained

Caractérisation de l'effet de la chaleur sur l'altération des cuirs et essais de restauration

National audienceLe but du projet BIORESTOCUIRS, financé par le LabEx PATRIMA, est de développer une nouvelle approche de restauration pour des cuirs ayant perdu leur souplesse à la suite d’altérations, en particulier après exposition à la chaleur. Cette méthode innovante, repose sur l’utilisation de molécules biologiques pour respecter la nature de l’objet et préserver son histoire et son devenir.Pour cela, différents cuirs de veau de tannage végétal (sumac ou mimosa) ont été étudiés. Un ensemble de méthodes physico-chimiques et biochimiques a permis de caractériser les cuirs avant et après exposition à la chaleur et valider l’hypothèse formulée initialement d’une agrégation protéique. Le procédé de restauration envisagé consiste à développer un traitement à base d’enzyme afin de rompre les agrégats protéiques néoformés suite à l’exposition à la chaleur et permettre aux cuirs de retrouver leurs propriétés élastiques. Cette méthode de restauration pourra être à long terme appliquée à des cuirs historiques d’origines variées afin de leur redonner de la souplesse et ainsi les rendre à nouveau manipulables

Pillaring effects in macroporous carrageenan-silica composite microspheres

The impregnation of a carrageenan gel by a silica sol is an efficient method to form a composite material which can be conveniently activated by CO2 supercritical drying. The textural properties of the solids have been characterized by nitrogen adsorption-desorption at 77K and their composition by thermogravimetric analysis and EDX microprobe. Morphology was examined by SEM. The silica-carrageenan composites present an open macroporous structure. Silica particles retained inside the gel behaved as pillars between the polysaccharide fibrils and form a stick-and-ball network. The stiffening of the carrageenan gel by silica prevented its shrinkage upon drying. The nature of the alkali cations affected the retention of silica particles inside the gel. In the absence of silica, carrageenan fibrils rearrange under supercritical drying and form an aerogel with cavities in the mesopore range

Evaluation of polyol-made Gd3+ -substituted Co0.6Zn0.4Fe2O4 nanoparticles as high magnetization MRI negative contrast agents

The structural, microstructural, and magnetic properties of ~5‐nm‐sized Co0.6Zn0.4Fe2−xGdxO4 nanoparticles were investigated in order to evaluate their capability to enhance the magnetic resonance imaging contrast as high magnetization agents. A focus was made on the solubility of Gd3+ cations within the spinel lattice. By coupling X‐ray diffraction to X‐ray fluorescence spectroscopy, we demonstrated that only a limited fraction of Gd3+ can substitute Fe3+ ions into the whole crystal structure and does not exceed 6 at.‐%. At this concentration, the room temperature (27°C) saturation magnetizations of the prepared superparamagnetic nanocrystals were found to be close to 80 emu g−1. Coating these nanoparticles with hydrophilic dopamine ligands leads to the formation of ~50‐nm‐sized clusters in water. As a consequence, relatively high r2/r1 ratios of transverse to longitudinal proton relaxivities and high r2 values were measured in the resulting colloids at physiological temperature (37°C) for an applied magnetic field of 1.41 T: 33 and 188 mM−1 sec−1, respectively, for the richest system in gadolinium. Moreover, after incubation with healthy human model cells (fibroblasts) at doses as high as 10 μg mL−1, they induce neither cellular death nor acute cellular damage making the engineered probes particularly valuable for negative magnetic resonance imaging contrasting.USPCScience and Engineering for Advanced Materials and device