Relevant insight of surface characterization techniques to study covalent grafting of a biopolymer to titanium implant and its acidic resistance

International audiencePeri-implant bacterial infections are the main cause of complications in dentistry. Our group has previously proposed the attachment of chitosan on titanium implants via a covalent bond to improve its antibacterial properties while maintaining its biocompatibility. A better knowledge of the coating preparation process allows a better understanding of the bioactive coating in biological conditions. In this work, several relevant characterization techniques were used to assess an implant device during its production phase and its resistance in natural media at different pH. The titanium surface was functionalized with 3-aminopropyltriethoxysilane (APTES) followed by grafting of an organic coupling agent; succinic anhydride, able to form two covalent links, with the substrate through a Ti-O-Si bond and the biopolymer through a peptide bond. Each step of the coating synthesis as well as the presence confirmation of the biopolymer on titanium after saliva immersion was followed by FTIR-ATR, SEM, EDS, 3D profilometry, XPS and ToF-SIMS analyses. Results allowed to highlight the efficiency of each step of the process, and to propose a mechanism occurring during the chitosan coating degradation in saliva media at pH 5 and at pH 3

Acidic pH resistance of grafted chitosan on dental implant

International audienceOver the last decade, access to dental care has increasingly become a service requested by the population, especially in the case of dental implants. However, the major cause of implant failure is an inflammatory disease: peri-implantitis. Currently, the adhesion strength of antibacterial coatings at implant surfaces remains a problem to solve. In order to propose a functionalized implant with a resistant antibacterial coating, a novel method of chitosan immobilization at implant surface has been investigated. Functionalization of the pre-active titanium (Ti) surface was performed using triethoxysilylpropyl succinic anhydride (TESPSA) as a coupling agent which forms a stable double peptide bond with chitosan. The chitosan presence and the chemical resistibility of the coating under acid pH solutions (pH 5 and pH 3) were confirmed by FTIR-ATR and XPS analyses. Furthermore, peel test results showed high adhesive resistance of the TESPSA/chitosan coating at the substrate. Cytocompatibility was evaluated by cell morphology with confocal imaging. Images showed healthy morphology of human gingival fibroblasts (HGF-1). Finally, the reported method for chitosan immobilization on Ti surface via peptide bindings allows for the improvement of its adhesive capacities and resistibility while maintaining its cytocompatibility. Surface functionalization using the TESPSA/chitosan coupling method is noncytotoxic and stable even in drastic environments as found in oral cavity, thus making it a valuable candidate for clinical implantology applications

Antibacterial activity of uncoated and chitosan coated samples after 24 h of direct contact.

<p>Antibacterial activity of uncoated and chitosan coated samples after 24 h of direct contact.</p

ToF-SIMS depth profiles of positive fragments recorded from chitosan coated sample (CSTPiTA6V).

<p>ToF-SIMS depth profiles of positive fragments recorded from chitosan coated sample (CSTPiTA6V).</p

Antibacterial activity of uncoated and chitosan coated samples after 24 h of direct contact.

<p>Antibacterial activity of uncoated and chitosan coated samples after 24 h of direct contact.</p

Atomic elemental composition percent for the individual reaction steps determined by XPS.

<p>The different surfaces obtained were labeled as follow: unmodified surface (T_A6V), piranha treated titanium alloy surface (PiT_A6V), TESPSA modified PiT_A6V (TPiT_A6V) and chitosan modified TPiTA6V surface (CSTPiT_A6V).</p

Specific positive and negative fragments of TESPSA and chitosan.

<p>Specific positive and negative fragments of TESPSA and chitosan.</p

Les recherches sur les publics en Sciences de l’Information et de la Communication

La notion de public n’a cessé d’être débattue par les sciences humaines et sociales depuis que ces dernières s’en sont emparées pour en faire un objet d’étude et de recherches. Cependant, très tôt, la notion de public a été dénoncée comme relevant d’un artefact conduisant à des représentations réductrices d’une réalité complexe. Hormis quelques articles pertinents et dossiers thématiques, le terme de « public », entendu au singulier, a été dissous depuis une quinzaine d’années dans son pluriel, dans une relative indifférence, et sans que la réflexion sur cette évolution ne réveille quelque appétit à la questionner. Or, l’emploi du pluriel, sur lequel les analystes du présent dossier semblent s’accorder, traduit une vision dynamique, la pluralité du phénomène, son hétérogénéité, la diversité ressentie, mais également un certain malaise quant à la manipulation du concept, lié à son instabilité… [En savoir +