ABSTRACT
Calcium phosphate layers were deposited on Ti6Al4V substrates with TiN buffer layers by use of pulsed laser deposition method. With this technique three pressed pellets consisted of tricalcium phosphate (TCP, Ca(3)(PO(4))(2)), hydroxyapatite (HA, Ca(10)(PO(4))(6)(OH)(2)) and hydroxyapatite-doped with magnesium (HA with 4% of Mg and trace amount of (Ca,Mg)(3)(PO(4))(2)) were ablated using ArF excimer laser (lambda=193 nm). The using of different targets enabled to determine the influence of target composition on the nature of deposited layers. The obtained deposits were characterized by means of Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction method (XRD). The obtained Fourier spectras revealed differences in terms of intensity of spectral bands of different layers. The analysis from XRD showed that Mg-doped HA layer has crystalline structure and TCP and HA layers composition is characterized by amorphous nature.
ABSTRACT
Thin films of ZrO2 and hydroxyapatite/ZrO2 were created by excimer laser ablation on Ti6Al4V substrates. ZrO2 layers were fabricated in vacuum by KrF laser at various substrate temperatures and hydroxyapatite (HA) layers were fabricated in water vapor ambient by ArF laser and in water vapor/argon ambient by KrF excimer laser. Film properties were evaluated by XRD, SEM and WDX methods. The test of mechanical adhesion was proceeded on ZrO2 films. XRD analysis proved the presence of amorphous or crystalline HA in the deposited films. SEM method demonstrated smooth surface covered by droplets for both HA and ZrO2 films. Ca/P ratio of the HA films is higher than that of the natural HA and is within the range of 2.8-3.0. The HA/ZrO2 and ZrO2 samples were tested in vitro for cytotoxicity. The best results were received by the HA/ZrO2 samples in the test of cytotoxicity. Fibroblasts cultivating with HA/ZrO2 samples exhibited subconfluent and confluent growth and showed fibronectin homogenously.
Subject(s)
Coated Materials, Biocompatible/chemistry , Durapatite/chemistry , Membranes, Artificial , Nanostructures/chemistry , Prostheses and Implants , Zirconium/chemistry , Durapatite/radiation effects , Hardness , Lasers , Materials Testing , Nanostructures/radiation effects , Nanostructures/ultrastructure , Surface Properties , Zirconium/radiation effectsABSTRACT
Guanine-based purines have been shown to modulate the effects of glutamate, which is essential for brain function and mediates excitotoxicity. In the search for a mechanism involving the interaction between purine nucleoside guanosine and glutamate, we found that guanosine dose-dependently, significantly (63%) and potently (EC50 =2.47 microM) enhanced glutamate uptake in cultured astrocytes. This effect was not inhibited by the blocker of nucleoside transporter dipyridamole nor by the adenosine antagonist theophylline, suggesting an extracellular site of action without the involvement of adenosine receptors. These results indicate a regulatory role of guanosine on extracellular levels of glutamate, possibly contributing for protecting neural cells against glutamate-induced excitotoxicity.
