ABSTRACT
Herein, we studied light induced interactions between two well-known luminescent materials, SrAl2O4:Eu2+, Dy3+ and nano-scale TiO2 in poly(methyl methacrylate) (PMMA). These two materials were chosen due to their stable nature, efficient spectral properties and more specifically, overlapping excitation/emission bands. When these materials were used together in 1:1 ratio by weight (w/w), the composite exhibited 76% enhancement in the emission intensity with respect to the individual phosphor. Although the luminescence mechanism of both materials is clarified in the literature, spectral interactions of them have not been studied up to now. In our opinion, the TiO2 nano-particles (TiO2 NPs) act as light-harvesting agents for the phosphor particles creating a substantial enhancement on the light absorption efficiency of the phosphor. Additionally, the TiO2 nanoparticles suggest a promising way to boost the phosphorescent activity of the SrAl2O4:Eu2+, Dy3+ by a cost-effective way and further investigation of the mechanism may be subject of future studies.
ABSTRACT
Hydroxyapatite (HAP) coatings are applied on metallic implant materials to combine mechanical properties of metallic material with bioactivity abilities of HAP ceramic. In this study, HAP coatings with additions of Si and Mg are proposed to be deposited on Ti6Al4V substrates by RF magnetron sputtering. Chemical bonding, morphology, topography and corrosion resistance in simulated body fluids (SBF) of the coatings were investigated. Additionally, mechanical and biological properties of the coatings were evaluated. It was found that the addition of Si and Mg does not influence the formation of a HAP phase. All the coatings exhibited smooth surface and uniform growth, without defects or cracks. Both hardness and elastic modulus of the coated samples decrease with Mg addition in the HAP-Si structure. Both Mg and Si addition into HAP coatings were found to enhance the corrosion resistance of the Ti6Al4V alloy in the SBF solution. Coatings with low Mg content exhibited better corrosion performance. All the coatings investigated were biocompatible, as demonstrated by SaOS-2 bone cell attachment and growth. However, cell proliferation and morphology were inferior on samples with the highest Mg content.
Subject(s)
Coated Materials, Biocompatible/chemistry , Durapatite/chemistry , Magnesium/chemistry , Silicon/chemistry , Alloys , Body Fluids/metabolism , Bone and Bones , Cell Adhesion , Cell Line, Tumor , Cell Proliferation , Corrosion , Elasticity , Electrochemical Techniques , Hardness , Humans , Materials Testing , Microscopy, Fluorescence , Osteoblasts/cytology , Osteoblasts/drug effects , Stress, Mechanical , Surface Properties , Titanium/chemistry , X-Ray DiffractionABSTRACT
Bioactive coatings are frequently used to improve the osseointegration of the metallic implants used in dentistry or orthopaedics. Among different types of bioactive coatings, hydroxyapatite (Ca10(PO4)6(OH)2) is one of the most extensively used due to its chemical similarities to the components of bones and teeth. In this article, production and characterization of hydroxyapatite films deposited on Ti6Al4V alloy prepared by magnetron sputtering were reported. Besides, SiC was deposited on substrate surface to study the interlayer effect. Obtained coatings were annealed at 600 °C for 30 and 120 min in a mixed atmosphere of N2 + H2O vapours with the heating rate of 12 °C min(-1). The effects of SiC interlayer and heat treatment parameters on the structural, mechanical and corrosion properties were investigated. After heat treatment process, the crystalline hydroxyapatite was obtained. Additionally, cell viability tests were performed. The results show that the presence of the SiC interlayer contributes a decrease in surface roughness and improves the mechanical properties and corrosion performance of the hydroxyapatite coatings. Biological properties were not affected by the presence of the SiC interlayer.
