Bruno Bujoli

Characterization and properties of novel gallium-doped calcium phosphate ceramics.

Addition of a gallium (Ga) precursor in the typical reaction protocols used for the preparation of β-tricalcium phosphate (β-TCP) led to novel Ga-doped β-TCP ceramics with rhombohedral structures (R3c space group). From the refinement of their X-ray diffraction patterns, it was found that the incorporation of Ga in the β-TCP network occurs by substitution of one of the five calcium (Ca) sites, while occupation of another Ca site decreases in inverse proportion to the Ga content in the structure. The Ga local environment and the modification of the phosphorus environments due to the Ga/Ca substitution in Ga-doped β-TCP compounds are probed using (31)P and (71)Ga magic-angle spinning NMR. A decrease of the unit cell volume is observed with increasing Ga content, together with improved mechanical properties. Indeed, the compressive strength of these new bioceramics is enhanced in direct proportion of the Ga content, up to a 2.6-fold increase as compared to pure β-TCP.

Chapter 13:Application of Metal Phosphonates to Biotechnologies

Since the late 70s, it has been demonstrated that phosphonic acids, RPO3H2[R is an organic component], have the ability to coordinate a wide range of cations, leading to the formation of PO–metal bonds which in some cases can be highly covalent. During the last two decades, this unique property has quite naturally led to the use of phosphonic acids as a route to functional materials by surface modification of metals and metal oxides, as well as any type of solid having surface exposed metal centers. This chapter will highlight how metal phosphonate chemistry can be used for the design of novel materials in the area of biotechnologies.Particular emphasis will be given to:the surface modification of various implants: with suitable terminal functions capable of inhibiting bacterial adhesion thus preventing biofilm formation and risks of infection, orwith bioactive molecules to favor interaction of the implant with cells or with drugs for the subsequent use of the implants as local drug delivery systems.the use of metal phosphonate surfaces for the purification of complex biological media, upon selective interaction with specific target molecules on the surface, orthe efficient and oriented immobilization of biological probes for the design of DNA or protein microarrays.the bioconjugation of nanoparticles for the design of platforms towards diagnosis or therapy.