Papers by Keyword: Biomimetism

Abstract: This contribution gathers various examples illustrating the fact that nanocrystalline apatites represent a genuine multi-functionalizable platform for a wide range of biomedical applications. It is indeed possible to convey additional functionalities to the already appealing properties of biomimetic apatites, via appropriate ionic substitutions and/or through controlled molecular adsorptions. In link with bone regeneration, we depict here examples of enhanced osteoconduction/induction and of the addition of antibacterial features to bone implants. But we also point out the promise of apatite-based colloidal nanoparticles in other domains not related to bone, such as nanomedicine (cell diagnosis/therapy), which we address by conferring luminescence properties and by adding cell recognition abilities.

Abstract: Long-term studies in the non-human primate Papio ursinus were set to investigate the induction of bone formation in biphasic hydroxyapatite tricalcium phosphate (HA/TCP) biomimetic matrices, 20/80 and 40/60, respectively. Biomimetic matrices were implanted in the rectus abdominis and in calvarial defects of 4 adult Papio ursinus. Morphological analyses on day 90 and 365 showed significant induction of bone formation within concavities of the biomimetic matrices implanted in both heterotopic and orthotopic sites with resorption of the implanted biomimetic matrices. The smart biomimetic matrices induced de novo bone formation even in the absence of exogenously applied osteogenic proteins of the transforming growth factor-β superfamily.

Abstract: ACP (amorphous calcium phosphate) and DCPD (dicalcium phosphate dihydrate, or Brushite) powders were high energy dry ball milled at a 1:1 ratio for 1, 2, 3, 4, 10, or 24 hours to produce a variety of powders for use as calcium phosphate cements (CPC). A 1:1 blend of powders not subjected to milling was used as baseline material (control). Physicochemical and mechanical characterization was performed on the powder or cement at each milling time point and compared to control. The following changes were noted after 24 hours of milling: the crystallinity was reduced to a fully amorphous phase, the tap density increased by 89%, the specific surface area decreased by a factor of 7, and the total porosity of hardened cement decreased by 50%. Additionally, the compressive strength of hardened CPC increased from 2.6 MPa to a peak of 50 MPa after 10-h milling. The rate of paste hardening increased throughout the 24-h period. Full conversion of each milled material produced a similar composition low-crystalline calcium deficiency apatite with Ca/P atomic ratio of 1.45 and specific surface area around 195 m2/g. The specific structure of these CPC, with high surface area and reactivity of nano-crystals, is ideal for in vivo remodeling of new bone and controlled release of protein and growth factors.