الفهرس 
constituents: cortex and cancellous bone.
Borate glass structureOnly 14 pages are availabe for public view
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Abstract
Factors such as the increasing aged population, bone degenerative diseases, fractures, and injuries have led to a great demand for synthetic bone replacement materials. Of these, bioactive glasses have risen as a primary choice due to their ability to convert to bone-like hydroxycarbonate apatite (HCA) mineral in biological solutions, which allows them to both chemically and physically bond to bone. In addition, their ability to homogeneously release ions can help stimulate the body’s natural repair mechanisms. Borate glass is more favorable than silicate glasses as it allows rapid and complete conversion to bone-like minerals of lower chemical durability. After the implantation of biomaterial into a living organism, the biochemical process that is responsible for osseointegration starts with ion dissolution. During all the steps that lead to the formation of the apatite layer on the top of the implant, only certain proteins are able to bind selectively and irreversibly to the implant surface, and this is influenced by ions released by bioactive glass, surface morphology, particle size and roughness, as well as concentration. Bioglass with nanoscale sizes and micro-/nano-structured surface topography shows superior bioactivity and promotes adhesion, proliferation, and subsequently stimulates bone growth. Laser irradiation in glass has been discovered to be a new and controlled method for selective assembly of nanoparticles or deposition of metallic nanoparticles within an amorphous glass matrix. The addition of various ions to the composition of bioactive glasses (doping) at a very low concentration compared to the main constituents improves their physical properties and therapeutic efficacy. In this thesis, a new types of borate modified Hench Bioglass® with the content (x-45) B2O3-(24.5) CaO-(24.5) Na2O-(6) P2O5 with the addition of (x = 1,2,5,7.5, 10) ZnO or SrCO3 (weight%) as two separated system have been prepared and characterized in which the quantity of borate was decreased by the addition of a dopant, whereas retaining the initial proportions of CaO, Na2O, and P2O5 with an aim to explore their biological activity. Then, selected glass samples have been irradiated with a nanosecond Neodymium Doped Yttrium Aluminum Garnet (Nd: YAG) laser for surface modifications in order to improve their biological activity for bone tissue engineering applications. All the glasses were characterized by a wide array of complementary characterization techniques before and after nanosecond laser irradiation, such as X-ray diffraction (XRD), Fourier transform infrared (FTIR), Scanning electron microscope (SEM) supported by energy dispersive x-ray analysis (EDAX) to investigate microstructure of the glasses before and after nanosecond laser irradiation, and also before and after in vitro test. Optical absorption spectral data using Ultraviolet and visible spectroscopy (UV/Vis.) was used to estimate different physical parameters including band gap energy (Eg) and the absorption of light energies by borate glass samples in UV and visible areas that give information about bridging and non bridging oxygen. In vitro test were studied for their bioactivity through immersion in simulated body fluid (SBF) for different time intervals (1 week, 2 weeks, 3 weeks, and 4 weeks) before and after nano second laser irradiation. Different physical parameters including density, molar volume, Packing density, and free volume were calculated. FTIR data preserve the presence of main structural units which result from borate matrix with the appearance of the characteristic FT infrared bands due to calcium phosphate (hydroxyapatite (HA)) after immersion which is considered as the potential indication of bone bonding ability. The results were confirmed through calculation of the four coordinated boron number (N4) that changes dramatically after one week immersion. X-ray diffraction pattern reveals the presence of HA within the glassy matrix after immersion instead of amorphous pattern of ordinary glassy state. SEM combined with EDX support the presence of HA after immersion. Distinct changes in physical parameters with nano second laser irradiation of the previous oxides suggesting use of this method for surface treatment and increase bioactivity. In conclusion, this dissertation has introduced a new class of rapidly HCA converting bioactive glasses, provided by using nano second laser irradiation process, resulting in enhanced the structural properties and making MBHGs promising candidates for bone tissue engineering applications.