Results
Phase 1: Laser fabrication and testing of ZnO thin films
We obtained ZnO thin films on stainless steel substrates by the PLD method, using a KrF* excimer laser source (λ = 248 nm, τFWHM ≤ 25 ns). The thin films were morphologically, compositionally and structurally characterized. SEM investigations performed on the sample obtained with the highest number of pulses, revealed a relatively uniform deposition, with specific ZnO structures and with a thickness of ~100 nm. The EDS spectra revealed both the substrate constituent elements and the ones characteristic of Zn and O. The crystalline structure of the ZnO thin films was revealed by XRD. By AFM it could be observed that the surface of the films was not smooth and the grains did not have a homogeneous distribution. The deposition of the multifunctional composites (BG57+0.01SIMV, BG57+0.02SIMV, BG57+NS) on stainless steel and Ti substrates was performed by the MAPLE method, using the same laser source. Also, within this phase, we developed a borate BG doped with Ce (BBGi); we deposited thin films of BBGi and BBGi+PVP. The surface morphology of the thin films deposited by MAPLE was examined by SEM. The MAPLE - obtained thin films were tested on the 3T3 osteoblast cell line. The results of the MTT assay demonstrated that the number of cells cultured on the BBGi films increased during the tested experimental period. LDH values obtained from cells grown on all films were not higher than those of the control, indicating no induction of cytotoxicity. BBGi-based films stimulated the production of reactive oxygen species by RAW macrophages and BG57-based films did not induce oxidative stress following co-cultivation with RAW macrophages. After the Live Dead test, it was observed that all MAPLE-obtained thin films are biocompatible, but the BBGi one presented the best degree of biocompatibility.
The results obtained in this phase allow the subsequent stages of the project to be carried out.