Electro-deposited Calcium-phosphate coatings for biomedical applications – DECaP

The consortium will thus use ElectroSpinning (ES) and Electrostatic Spray Deposition (ESD) to fabricate (and characterize) osseoconductive coatings of optimized architectures, compositions and structures (amorphous or crystalline), on biomedical grade titanium substrates. We will aim at biologically reactive coatings such as out-of-equilibrium or amorphous calcium phosphates (highly difficult to stabilize as coatings by any other technique, thus their potential as osseoconductive coatings could never be assessed) or bioactive glasses (whose synthesis has never been attempted using ESD). Moreover, we will look for architectures that promote reactivity and mechanical adhesion to bone tissues: dense coatings with arborescent surface, and porous coatings with a large amount of porosity (easily obtained with ES), or even with a multiscale architecture (network of tubular pores inside a coral-like dense matrix).

The main results expected form the project were to obtain amorphous or out-of-equilibrium calcium phosphate phases stable with time, which is a real challenge. UUnderstanding the stabilisation mechanisms of these phases will pave the way to new materials with original properties.
Our first results are promising, and demonstrate the feasability of the project.

After the necessary developments, DECaP results will allow the iindustrial mplementation opf new processes for more efficient and cheaper CaP coatings on biomedical implants.The improved osseoconductivity of thee coatings will allow faster healing of the patients, therebye reducing hospitalisaton costs.

communications in 3 international conferences.

Every year, more than 200 000 orthopaedic prostheses (knee, hip) and a huge (but unknown) number of dental implants are implanted in France. For an optimal efficiency, these implants have to be well integrated in bone. To favour osseointegration, dental implants rely on modification of their surface morphology, while a Calcium-Phosphate coating is often required on the surface of orthopaedic implants. Traditionally, these coatings are fabricated by plasma-spray, leading to well crystallized films in the most stable phases (mainly hydroxyapatite).Even though these plasma-sprayed coatings are commonly used on stems and metal-backs of hip prostheses, their efficiency is subject to controversy because of several drawbacks such as the excessive thickness of the coatings, their possible delamination leading to local inflammations, and the overly stable nature of the constitutive materials that do not favour reactivity.
DECaP project aims at developing alternative coating techniques, less costly and leading more efficient coatings (with higher adhesion to substrate, more reactive to allow faster bone ongrowth and faster healing of the patient) potentially applicable to both dental and orthopaedic implants.
The consortium will thus use ElectroSpinning (ES) and Electrostatic Spray Deposition (ESD) to fabricate (and characterize) osseoconductive coatings of optimized architectures, compositions and structures (amorphous or crystalline), on biomedical grade titanium substrates. We will aim at biologically reactive coatings such as out-of-equilibrium or amorphous calcium phosphates (highly difficult to stabilize as coatings by any other technique, thus their potential as osseoconductive coatings could never be assessed) or bioactive glasses (whose synthesis has never been attempted using ESD). Moreover, we will look for architectures that promote reactivity and mechanical adhesion to bone tissues: dense coatings with arborescent surface, and porous coatings with a large amount of porosity (easily obtained with ES), or even with a multiscale architecture (network of tubular pores inside a coral-like dense matrix).
As a proof of concept, these findings will be applied to a real dental implant.
The expected outputs of this project are:
- Scientific: obtaining stable over time, out-of-equilibrium, reactive CaP or bioactive glass phases is a scientific challenge. Understanding how these phases are stabilized during the process could open the way to new materials with original properties (reactivity, transport…)
- Industrial: after further development, the findings of DECaP project will allow biomaterial companies to implement new processes leading to innovative and efficient coatings for improved osseoconductivity of biomedical implants.
- Societal: the improved osseoconductiviy of these implants will allow faster healing of the patients, thus better comfort, shorter treatments thus lower treatment cost and hopefully better long term success. Besides these cheaper coatings will help reduce the price of implants.
DECaP consortium combines the competencies of three laboratories: MATEIS will bring its knowledge of calcium phosphates and extensive, in-situ characterization. LEPMI will use its in-depth understanding and practice of Electrostatic Spray Deposition, already applied with great success to the fabrication of Solid Oxide Fuel Cell components. LMI masters Electro Spinning, that was used (combined with sol-gel chemistry) to fabricate original and architectured materials.The synergy between the three laboratories will allow reaching our ambitious goals.