Surface properties of biomimetic nanocrystalline apatites; applications in biomaterials

Several types of nanocrystalline apatites have been described, obtained in various ways. Among these, biomimetic nanocrystalline apatites (BNA), whose characteristics are close to those of biological apatites, have been shown to exhibit specific properties mainly related to their surface structure and composition. The aim of this paper is to review current knowledge of these compounds

Adsorption on apatitic calcium phosphates for drug delivery: interaction with bisphosphonate molecules

Bisphosphonates (BPs) are well established as an important class of drugs for the treatment and prevention of several bone disorders including osteoporosis. This work investigated the interaction of two bisphosphonates, risedronate and tiludronate, with several apatitic supports, a well-crystallised hydroxyapatite (HA) and nanocrystalline apatites with varying maturation times, chemical composition and surface characteristics. The purpose was to fully understand the adsorption mechanism and desorption process, by the evaluation of the effect of several physicochemical parameters (temperature, pH and concentration of calcium and phosphate ions). Whatever the nature of the BP and the structure and composition of the apatite, the adsorption of such anti-resorptive agents can be well described as an ion exchange-reaction between phosphates species on the apatitic surface and BP molecules in solution. However, the parameters of adsorption can vary depending on the physicochemical conditions of the adsorption reaction. In addition, the structure and composition of the apatitic surface also influence the adsorption properties. Finally, BPs molecules are slowly released from apatitic supports, because most of the adsorbed molecules are irreversibly bound and not spontaneously released by dilution or simple washing. Moreover, similar to their adsorption, the release of bisphosphonates is strongly affected not only by the chemical properties of the molecule, but also by the chemical and structural characteristics of the apatitic substrates. The understanding of the adsorption and release processes provides fundamental tools for the development of drug delivery systems using apatite materials

Multifunctionalization Modulates Hydroxyapatite Surface Interaction with Bisphosphonate: Antiosteoporotic and Antioxidative Stress Materials

Multifunctionalized biomaterials with enhanced bone antiresorptive properties were obtained through adsorption of a bisphosphonate, risedronate, on hydroxyapatite (HA) nanocrystals functionalized with zinc ions and polyethylenimine (PEI). Zn incorporation into the HA structure amounts to about 8 atom %, whereas the PEI content of the bifunctionalized material ZnHAPEIBP is about 5.9 wt %. The mechanism of adsorption and release of the bisphosphonate on ZnHAPEI is compared with that on ZnHA: risedronate adsorption isotherm on ZnHA is a Langmuir type, whereas the isotherm of adsorption on ZnHAPEI is better fitted with a Freundlich model and involved a higher amount of adsorbed risedronate. In vitro cell tests were carried out with a coculture model of osteoblasts and osteoclasts using a model simulating oxidative stress and consequent cellular senescence and osteoporosis by the addition of H2O2. The conditions utilized in the coculture model strongly affect osteoblast behavior. The results show that the composite materials allow an increase in osteoblast viability and recover impairment, revealing a novel characteristic of risedronate that is able to counteract the negative effects of oxidative stress when associated with differently functionalized samples. Both PEI and the bisphosphonate reduce osteoclast viability. Moreover, PEI, and even more risedronate, exerts an inhibitory effect on osteoclast activity

Hydroxyapatite functionalization to trigger adsorption and release of risedronate

Bisphosphonates are widely employed drugs for the treatment of pathologies characterized by excessive bone resorption, and display a great affinity for apatitic supports. In this work we investigate how hydroxyapatite functionalization can influence the processes of adsorption and release of a bisphosphonate, namely risedronate. To this aim, pure hydroxyapatite (HA), hydroxyapatite with a partial substitution of Zn to Ca (ZnHA) and poly-ethylenimine-functionalized hydroxyapatite (HAPEI) were submitted to interaction with risedronate solution. The results indicate that the mechanisms of adsorption and release are greatly influenced by the type of the apatitic support. All the apatitic supports display Langmuir isotherms for risedronate adsorption. However in the case of HAPEI the plateau is not reached even at high equilibrium concentrations in solution. The data suggest that risedronate adsorption on HAPEI mineral-organic support occurs not only through chemisorption on apatitic phase, as on HA and ZnHA, but also through physisorption involved by PEI coating, which modulates also bisphosphonate release. These properties of tailor-made hydroxyapatite supports could be exploited to develop delivery systems for antiresorptive agents directly on osteoporotic sites

"Une paire de vases en porcelaine chinoise"

International audiencePaire de vases montés en porcelaine de Chine pour le musée national de la céramique de Sèvre

Victor Collin de Plancy and the knowledge of Korea in the West

En 1886 est signé le premier traité d'amitié signé entre la France et la Corée. Victor Collin de Plancy, consul ayant commencé sa carrière en Chine est le premier représentant de la France dans ce "Royaume ermite" resté longtemps fermé à l'étranger. En 1906, il est le dernier représentant occidental à quitter le pays après l'annexion de la Corée par le Japon vainqueur de la Russie lors du conflit russo-japonais de 1904-1905. Pendant ces vingt années il accumule des objets et diffuse en France les collections et les connaissances sur le petit pays extrême-oriental. Les collections coréennes présentées aujourd'hui en France (musée national des arts asiatiques Guimet, musée national de la céramique de Sèvres, Bibliothèque nationale de France) sont encore en grande partie liées à ses collections. La thèse se propose d'analyser son rôle dans la connaissance de la Corée en Occident, en présentant son parcours professionnel, familial et intellectuel et la Corée telle qu'il la découvre en 1886,ainsi que les efforts qu'il entreprend pour la révéler en France depuis ses collectes pour les musées parisiens, jusqu'à la participation de la Corée à l'exposition universelle de 1900. Il est également au cœur d'un réseau d'amis de la Corée qu'il mobilise au service du pays, depuis Charles Varat, explorateur et collecteur, jusqu'à Maurice Courant, premier coréanologue français et auteur d'une essentielle Bibliographie coréenne.1886 marks the beginning of the diplomatic relationship between France and Korea. Victor Collin de Plancy, french diplomat who began his carrier in China,was appointed first diplomat of France in the long closed to foreign influences "Ermit Kingdom". in 1906, he was the las foreign diplomat to leave Korea after the country became a part of the Japan Empire following the success of the Japanese against Russia in the Russian-Japanese war of 1904-1905. These 20 years allowed Collin de Plancy to collect informations and korean objects for the French institutions. Most Korean collections held today in French museums (musée national des arts asiatiques Guimet, musée national de la céramique de Sèvres, Bibliothèque nationale de France), can be traced back to his traced. This work analyzes his central role for the knowledge of Korea in the West, presenting his professional, personal and intellectual evolution and the Korea he discovers in 1886, as well as the efforts he made to reveal the country in France from the collects for Parisian Museums to the Korean participation to the 1900 Paris Universal Exhibition. He was also at the centre of a group of friends of Korea from Charles Varat, traveler and collector, to Maurice Courant, first French Koreanologist who wrote a very famous Bibliographie coréenne

Victor Collin de Plancy et la connaissance de la Corée en Occident

1886 marks the beginning of the diplomatic relationship between France and Korea. Victor Collin de Plancy, French diplomat who began his carrier in China, was appointed first diplomat of France in the long closed to foreign influences “Ermit Kingdom”. In 1906 he was the last foreign diplomat to leave Korea after the country became a part of the Japan Empire following the success of the Japanese against Russia in the Russian-Japanese war of 1904-1905. These 20 years allowed Collin de Plancy to collect informations and Korean objects for the French institutions. Most Korean collections held today in French museums (Musée Guimet, Musée national de la céramique de Sèvres, Bibliothèque Nationale de France), can be traced back to his efforts. This work analyses his central role for the knowledge of Korea in the West, presenting his professional, personal and intellectual evolution et the Korea he discovers in 1886, as well as the efforts he made to reveal the country in France from the collects for Parisian Museums to the Korean participation to the 1900 Paris Universal Exhibition. He was also at the centre of a group of friends of Korea from Charles Varat, traveler and collector, to Maurice Courant, first French Koreanologist who wrote a very famous Bibliographie coréenne.En 1886 est signé le premier traité d’amitié entre la France et la Corée. Victor Collin de Plancy, consul ayant commencé sa carrière en Chine est le premier représentant de la France dans ce « Royaume ermite » resté longtemps fermé à l’étranger. En 1906, il est le dernier représentant occidental à quitter le pays après l’annexion de la Corée par le Japon vainqueur de la Russie lors du conflit russo-japonais de 1904-1905. Pendant ces vingt années il accumule des objets et diffuse en France les collections et les connaissances sur le petit pays extrême-oriental. Les collections coréennes présentées aujourd’hui en France (musée national des arts asiatiques Guimet, musée national de la céramique de Sèvres, Bibliothèque Nationale de France) sont encore en grande partie liées à ses collectes.La thèse se propose d’analyser son rôle dans la connaissance de la Corée en Occident, en présentant son parcours professionnel, familial et intellectuel et la Corée telle qu’il la découvre en 1886, ainsi que les efforts qu’il entreprend pour la révéler en France depuis ses collectes pour les musées parisiens, jusqu’à la participation de la Corée à l’exposition universelle de 1900. Il est également au cœur d’un réseau d’amis de la Corée qu’il mobilise au service du pays, depuis Charles Varat, explorateur et collecteur, jusqu’à Maurice Courant, premier coréanologue français et auteur d’une essentielle Bibliographie coréenne

Maurice Courant

Notice dans le dictionnaire des historiens de l'art français, Publication numérique, Institut national d'histoire de l'ar

Refléter le passé : les faux bronzes en porcelaine sous le règne de l’empereur Qianlong (1735-1785)

International audienceNouveaux champs de l'histoire sociale 31 | 2019 : Vrai ou faux ? : qualifier les porcelaines de Chine (XV e-XXI e siècle) Dossier : Vrai ou faux ? : qualifier les porcelaines de Chine (XVe-XXIe siècle) Refléter le passé : les faux bronzes en porcelaine sous le règne de l'empereur Qianlong (1735-1785) Reflecting the past : Porcelain fake bronzes during the reign of Emperor Qianlong (1735-1785) Reflejar el pasado : los bronces falsos de porcelana durante el reinado del Emperador Qianlong (1735-1785) S

Rôle des connecteurs dans l'établissement de la cohérence (apports du vieillissement normal et pathologique)

MONTPELLIER-BU Lettres (341722103) / SudocSudocFranceF