Spectral Analysis of Strontium-Doped Calcium Phosphate/Chitosan Composite Films

Abstract

Strontium-doped calcium phosphate/chitosan films were synthetized on silicon substrates using the radio-frequency magnetron sputtering technique and the matrix-assisted pulsed laser evaporation technique. The deposition conditions associated with the radio-frequency magnetron sputtering discharge, in particular, include the high temperature at the substrate, which promotes the formation of strontium-doped tetra calcium phosphate layers. The physical and chemical processes associated with the deposition of chitosan on strontium-doped calcium phosphate layers were investigated using Fourier Transform Infrared Spectroscopy, Energy Dispersive X-ray Spectroscopy, and Scanning Electron Microscopy. Mass spectrometry coupled with laser induced ablation of the composite films proved to be a useful tool in the detection of the molecular ions characteristic to chitosan chemical structure.

Calcium Orthophosphate (CaPO4) Containing Composites for Biomedical Applications: Formulations, Properties, and Applications

“…The bands' shift in the fingerprint region suggested that hydroxides and orthophosphate on the HA surface can interact by nucleophilic addition with the plentiful carboxyl and amino groups of PA [269]. Similar conclusions were drawn for many other CaPO 4 -containing composites and hybrid formulations, namely: HA/PVA [626], CDHA/alginate [715], ACP/PPF [469], HA/maleic anhydride [302], HA/carboxylated PU [1198], HA/chitosan [821,1200,1201], and β-TCP/PLLA [405] biocomposites. It has been shown that weak chemical bonds are formed between Ca 2+ ions on the surfaces of HA, CDHA, ACP, or β-TCP, respectively, and the slightly polarized O atoms of C=O bonds in the surrounding bio-organic compounds.…”

“…FTIR spectroscopy appears to be a very useful technique for examining possible chemical bonding between phases in hybrid formulations and composites based on CaPO 4 [186,269,295,301,302,405,469,597,608,619,621,623,626,630,640,676,677,680,685,715,749,802,803,821,848,875,919,[1192][1193][1194][1195][1196][1197][1198][1199][1200][1201]. For example, in HA/PE biocomposites, the characteristic bands of the hydrocarbon backbone of PE at 2918, 2850, and 1472 cm −1 show zero shift, while, in HA/PA, bands at 3304, 1273, and 692 cm −1 derived from N-H stretching, C-N-H stretching, and N-H vibrations are observed in HA/PA, which move to 3306, 1275, and 690 cm −1 in biocomposites.…”

“…Furthermore, using ab initio techniques, the chemical interactions between HA and organic compounds have been clarified [1204]. Other measuring methods can also demonstrate proof of phase-to-phase chemica interactions in CaPO4-based composites and hybrid formulations [295,405,621,622,626,[1193][1194][1195][1196][1197][1198][1199][1200][1201][1202][1203]. For example, such evidence has been observed in nanosized crystals of CDHA/alendronate by thermogravimetric analysis: the DTG plots of the crystals appear quite different from those obtained from a mechanical mixture o CDHA and calcium alendronate of similar composition [1202].…”