Bioglass Thin Films For Biomimetic Implants

摘要

Pulsed laser deposition (PLD) method was used to obtain bioglass (BG) thin film coatings on titanium substrates. An UV excimer laser KrF~* (λ = 248 ran, τ = 25 ns) was used for the multi-pulse irradiation of the BG targets with 57 or 61 wt.% SiO_2 content (and Na_2O-K_2O-CaO-MgO-P_2O_5 oxides). The depositions were performed in oxygen atmosphere at 13 Pa and for substrates temperature of 400 ℃. The PLD films displayed typical BG of 2-5 μm particulates nucleated on the film surface or embedded in. The PLD films stoichiometry was found to be the same as the targets. XRD spectra have shown, the glass coatings obtained, had an amorphous structure. One set of samples, deposited in the same conditions, were dipped in simulated body fluids (SBFs) and subsequently extracted one by one after several time intervals 1,3,7, 14 and 21 days. After washing in deionized water and drying, the surface morphology of the samples and theirs composition were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), 1R spectroscopy (FTIR) and energy dispersive X-ray analysis (EDX). After 3-7 days the Si content substantially decreases in the coatings and PO_4~(3-) maxima start to increase in FTIR spectra. The XRD spectra also confirm this evolution. After 14-21 days the XRD peaks show a crystallized fraction of the carbonated hydroxyapatite (HAP). The SEM micrographs show also significant changes of the films surface morphology. The coalescence of the BG droplets can be seen. The dissolution and growth processes could be assigned to the ionic exchange between BG and SBFs.