Cell behavior at surface of polyelectrolyte films deposited on titanium

OBJECTIVES: Optimization of surface properties is a recent and crucial issue in the biomaterial fields applied to Odontology. The reference biomaterial in dental implantology is titanium. The principal objective is a perfect bio-integration of such a material in the oral ecosystem, both in terms of mucosal and bone tissues.The aim of this work was to optimize tissue-titanium interface by applying polyelectrolyte multilayer films on the surface of titanium. METHODS: The experimental study was undertaken on pure titanium samples with an average surface roughness of Ra = 0,3 µm. Four types of polyelectrolyte films were initially built, all with a first poly-ethylene-imine (PEI) base layer, then composed either of poly-styrene-sulphonate (PSS) and poly-allylamine-hydrochlorid (PAH) or of hyaluronan acid (HA) and poly-L-lysin (PLL) layers. Final architectures were as follows : PEI-(PSS/PAH)10, or PEI-(PSS/PAH)10-PSS, or chemically cross-linked PEI-(HA/PLL)10 or chemicaly cross-linked PEI-(HA/PLL)10-HA. An analysis of the physicochemical characteristics of the surfaces was carried out by tensiometry measurments, atomic force microscopy and confocal microscopy. A biological study with human fibroblasts was undertaken at J0, J2, J4 and J7 to observe the cellular response in terms of morphology (scanning electron microscopy), adhesion (fluorescence microscopy image analysis) and proliferation (Mosmann's test). RESULTS: The results showed that polyelectrolyte multilayer films can be successfully deposited onto titanium as previously described for glass or composite. Furthermore, films containing PSS/PAH generate a better cellular response than films containing cross-linked HA/PLL as shown by an increase in both fibroblast cell adhesion and proliferation. CONCLUSIONS: Biomaterials coatings using PSS/PAH polyelectrolytes films represent a new approach for oral bio-integration with great potential for clinical application in implantology. More particularly, specific biofuctionalization of these films can be envisioned by introducing between the films layers molecules that encourage the bio-integration process.