towArd a sWitchable biO-activity of metalliC glass surfAces by ultrashort laser irradiaTion – AWOCAT

Biomaterials, as well as nosocomial diseases got in contaminated environments, are two high-societal impact issues, where development of new metallic glasses (MGs) may contribute to improve significantly the performance of medical devices. Indeed, these innovative homogeneous defect-free materials may present a really versatile behaviour, depending on their chemical composition. Nevertheless, if MGs show unique mechanical and corrosion properties, synthesis of bulk MGs is very complicated and expensive, so that their industrial development still remains limited. to date, two distinct ways are studied involving (i) biomaterials attesting high physico-chemical properties but which are expensive and difficult to synthesize, or (ii) functionalisation and/modification of the surface, but through processes susceptible to affect its initial characteristics.
The alternative proposed within AWOCAT's project is twofold, and relies on the development of metallic glasses under the form of thin micrometric films by vacuum processes (PVD), combined with a ultrashort post-irradiation leading to a controlled texturing of the surface. The control of these two independent parameters gives to the modified surface a versatile bio-activity, while its other high functional properties inherent to the MG structure are preserved. Through such a dual PVD vs laser process, all parameters governing the modified surface nature (substrate nature, film's chemical composition, microstructure, durability…) and texture (design, local induced devitrification, wettability…) are thoroughly under control. Three types of coatings will be analysed: Zr-Cu-Ag, Zr-Ti-Al et Mg-Cu-Ca alloys, investigated for their antimicrobial, biostatical and biocompatible capabilities, respectively. Regarding the ultrashort laser treatments, several surface structuring will be investigated with dimensions designed to prevent microbes adhesion, or, in opposite, with a complex multiscale texture to favor cellular attachment and proliferation.
It is established that both the film's chemistry and its topography may influence the biological affinity of the surface. In this context, AWOCAT's objective is then to explain the respective role of the MG's chemical composition on the one hand, of the ultrashort laser nanostructuring on the other hand, on the micro-organisms dynamics. Not only human cells and bacteria will be considered, but also viruses, which are most often neglected. Therefore, AWOCAT's objective consists to deliberately switch the biological behaviour of a material, from a biocide character prone to fight hospital-acquired infections, to, in opposite, a total biocompatibility as a breakthrough solution to promote biomaterials.
To undertake such challenges, AWOCAT gathers complementary competencies of four academic laboratories (MATEIS, Lyon-Microstructural and biological characterisation ; LabHC, St Etienne- ultrashort laser/film interaction ; IJL, Nancy- films deposition and analysis ; Sainbiose, St Etienne-Biocompatibility characterization), associated with a socio-economical partner, Anthogyr (Sallanches), world-known end-user in the field of dental surgery and implantology. AWOCAT is structured into four tasks, dedicated: to PVD deposition process and characterization (T1), to the laser treatment of nanostructuration (T2), to the biological characterization of modified surfaces at the laboratory-scale (T3) and face to industrial realistic conditions (T4). The project duration is 48 months, and involves one PhD, 2 18-month post-doctorants and 2 master students.