The Effects of Electron Beam Irradiation on the Morphological and Physicochemical Properties of Magnesium-Doped Hydroxyapatite/Chitosan Composite Coatings

Abstract

This work reports on the influence of 5 MeV electron beam radiations on the morphological features and chemical structure of magnesium-doped hydroxyapatite/chitosan composite coatings generated by the magnetron sputtering technique. The exposure to ionizing radiation in a linear electron accelerator dedicated to medical use has been performed in a controllable manner by delivering up to 50 Gy radiation dose in fractions of 2 Gy radiation dose per 40 s. After the irradiation with electron beams, the surface of layers became nano-size structured. The partial detachment of irradiated layers from the substrates has been revealed only after visualizing their cross sections by scanning electron microscopy. The energy dispersive X-ray spectral analysis of layer cross-sections indicated that the distribution of chemical elements in the samples depends on the radiation dose. The X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and X-ray diffraction analysis have shown that the physicochemical processes induced by the ionizing radiation in the magnesium doped hydroxyapatite/chitosan composite coatings do not alter the apatite structure, and Mg remains bonded with the phosphate groups.

Keywords: electron beam irradiations; magnesium-doped hydroxyapatite/chitosan composite coatings; magnetron sputtering technique.

Figure 1

SEM images of: (a) unirradiated; (c) 2 Gy irradiated; (e) 50 Gy irradiated; MgHApCs layers. 3D surface plot of SEM images of: (b) unirradiated; (d) 2 Gy irradiated; (f) 50 Gy irradiated; MgHApCs layers.

Figure 2

SEM depth profiles and cross-section images of: (a) unirradiated; (b) 2 Gy irradiated; (c) 50 Gy irradiated; MgHApCs layers. EDS depth profiles of (a) unirradiated; (b) 2 Gy irradiated; (c) 50 Gy irradiated; MgHApCs layers.

Figure 3

Evolution of atomic percentage of the following elements: (a) Ca; (b) P; (c)Mg; (d) C; (e) O; (f) N; (g) Si in unirradiated and irradiated MgHApCs coatings deposited on Si substrates. 3(h) EDS spectrum of unirradiated MgHApCs layer.

Figure 4

SEM images of adhesion tape tests of: (a) unirradiated MgHApCs; (b) 2 Gy irradiated MgHApCs; (c) 50 Gy irradiated MgHApCs; layers.

Figure 5

XPS Survey spectra of unirradiated and irradiated MgHApCs layers.

Figure 6

High-resolution XPS lines of: (a–c) Mg 2p in unirradiated and irradiated MgHApCs samples; (d–f) P 2p in unirradiated and irradiated MgHApCs samples; (g–i) N 1s in unirradiated and irradiated MgHApCs samples.

Figure 7

FTIR absorbance spectra of sputtering target, unirradiated and irradiated MgHApCs layers.

Figure 8

Second order derivative of: (a) sputtering target; (c) unirradiated; (e) 2 Gy irradiated; (g) 50 Gy irradiated; MgHApCs layer. Deconvoluted IR bands of: (b) sputtering target; (d) unirradiated; (f) 2 Gy irradiated; (h) 50 Gy irradiated; MgHApCs layer.

Figure 9

XRD patterns of the: (a) unirradiated; (b) 2 Gy irradiated; (c) 50 Gy irradiated; MgHApCs layers.