Acidic pH resistance of grafted chitosan on dental implant.

Over 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.

Collagen implants equipped with 'fish scale'-like nanoreservoirs of growth factors for bone regeneration.

Implants triggering rapid, robust and durable tissue regeneration are needed to shorten recovery times and decrease risks of postoperative complications for patients. Here, we describe active living collagen implants with highly promising bone regenerative properties. Bioactivity of the implants is obtained through the protective and stabilizing layer-by-layer immobilization of a protein growth factor in association with a polysaccharide (chitosan), within the form of nanocontainers decorating the collagen nanofibers. All components of the implants are US FDA approved. From both in vitro and in vivo evaluations, the sophisticated strategy described here should enhance, at a reduced cost, the safety and efficacy of the therapeutic implants in terms of large bone defects repair compared with current simplistic approaches based on the soaking of the implants with protein growth factor.

Osteogenetic properties of electrospun nanofibrous PCL scaffolds equipped with chitosan-based nanoreservoirs of growth factors.

Bioactive implants intended for rapid, robust, and durable bone tissue regeneration are presented. The implants are based on nanofibrous 3D-scaffolds of bioresorbable poly-ϵ-caprolactone mimicking the fibrillar architecture of bone matrix. Layer-by-layer nanoimmobilization of the growth factor BMP-2 in association with chitosan (CHI) or poly-L-lysine over the nanofibers is described. The osteogenetic potential of the scaffolds coated with layers of CHI and BMP-2 is demonstrated in vitro, and in vivo in mouse calvaria, through enhanced osteopontin gene expression and calcium phosphate biomineralization. The therapeutic strategy described here contributes to the field of regenerative medicine, as it proposes a route toward efficient repair of bone defects at reduced risk and cost level.

Electrospun nanofibrous 3D scaffold for bone tissue engineering.

Tissue engineering aims at developing functional substitutes for damaged tissues by mimicking natural tissues. In particular, tissue engineering for bone regeneration enables healing of some bone diseases. Thus, several methods have been developed in order to produce implantable biomaterial structures that imitate the constitution of bone. Electrospinning is one of these methods. This technique produces nonwoven scaffolds made of nanofibers which size and organization match those of the extracellular matrix. Until now, seldom electrospun scaffolds were produced with thickness exceeding one millimeter. This article introduces a new kind of electrospun membrane called 3D scaffold of thickness easily exceeding one centimeter. The manufacturing involves a solution of poly(ε-caprolactone) in DMF/DCM system. The aim is to establish parameters for electrospinning in order to characterize these 3D scaffolds and, establish whether such scaffolds are potentially interesting for bone regeneration.

Smart hybrid materials equipped by nanoreservoirs of therapeutics.

Nanobiotechnology enables the emergence of entirely new classes of bioactive devices intended for targeted intracellular delivery for more efficacies and less toxicities. Among organic and inorganic approaches currently developed, controlled release from polymer matrices promises utmost clinical impact. Here, a unique nanotechnology strategy is used to entrap, protect, and stabilize therapeutic agents into polymer coatings acting as nanoreservoirs enrobing nanofibers of implantable membranes. Upon contact with cells, therapeutic agents become available through enzymatic degradation of the nanoreservoirs. As cells grow, divide, and infiltrate deeper into the porous membrane, they trigger slow and progressive release of therapeutic agents that, in turn, stimulate further cell proliferation. This constitutes the first instance of a smart living nanostructured hybrid membrane for regenerative medicine. The cell contact-dependent bioerodable nanoreservoirs described here will permit sustained release of drugs, genes, growth factors, etc., opening a general route to the design of sophisticated cell-therapy implants capable of robust and durable regeneration of a broad variety of tissues.

'All-supramolecular' nanocapsules from low-molecular weight ureas through interfacial addition reaction in miniemulsion.

This contribution presents a new strategy for preparing nanocapsules with a shell made of a supramolecular polymer which repeating units are held together by reversible interactions rather than covalent bonds. These nanocapsules were prepared in classical miniemulsion through interfacial addition reaction of a diisocyanate (IPDI) and a monoamine (iBA), forming low-molecular weight bis-ureas moieties which are strong self-complementary interacting molecules through hydrogen-bonding. The nanocapsules present a diameter around 100 nm, and MALDI-TOF MS and (1)H NMR analyses confirm the expected molecular characteristics for the shell. This strategy opens the scope of a new type of nanomaterials exhibiting stimuli-responsiveness due to the reversible interaction linking the repeating units.