Sharif Digital Repository

With the increase in the average age of the world's population, osteoporosis is a worldwide incidence. This disease, along with natural disasters, are important factors in the occurrence of fractures in various bones of the body. One of the methods for solving this problem and replacing with broken body bones is the use of metal implants with hydroxyapatite-based coatings. One of the common problems with using implants in the body is the infection in the adjacent parts of the implant. To overcome this problem, several studies have been carried out on the use of hydroxyapatite coatings with metal ions or antibacterial oxide compounds. In the present study, the influence of factors such as the... 

The purpose of this study was aimed to evaluate the effect of Alumina on the sintering, phase development, mechanical properties and biocompatibility of fluoridated hyroxyapatite sintered via conventional furnace and microwave assisted oven. Green compacts having 30wt% Alumina nanoparticles were sintered without pressure at various temperatures (1000-1400°C) for one hour in conventional furnace. Phase composition, thermal behavior and morphological analyses were performed using X-ray diffraction (XRD), simultaneous thermogravimetry and differential thermal analysis (STA), and Scanning Electron Microscopy (SEM), respectively. With the increase in temperature and the Alumina content, severe... 

Fixation devices and implants are the most applied devices in orthopedic operation and dentistry. Interference screw is one of these devices that is made by biodegradable nanocomposite polymeric materials in this project. The purpose of this project is designing interference screw, applicable to body, and doing related tests since in vivo tests. For this purpose, hand injection molding, was designed to prepare screws in laboratory scale, first. For making samples, poly(D,L) lacticacid, nano hydroxyapatite as reinforce and polyethylene glycol as plasticizer were used. These samples were made by combination of solvent casting and melt processing methods. Adding nano hydroxyapatite and... 

Hydroxyapatite (HA) is an attractive biomaterial due to its close chemical composition to bone and teeth. However, HA is brittle and has low strength under bearing loads, resulting in limition for orthopedic and dental applications. Two creative approaches have been developed to overcome this problem, using bioactive HA as coatings on metallic implants or as ceramic/metal composites. Carbon nanotubes (CNT) possess excellent mechanical properties to play the role as reinforcement for imparting strength and toughness to brittle hydroxyapatite (HA) bioceramic coating. Moreover, The addition of TiO2 to HA coatings has attracted considerable attention, since TiO2 is capable of increasing the... 

Hydroxyapatite (HA) is the most substantial mineral constituent of a bone which displays splendid biocompatibility and bioactivity properties. Nevertheless, its mechanical property is not utmost appropriate for a bone substitution. Therefore, a composite consist of HA and a biodegradable polymer is usually prepared to generate an apt bone scaffold. In the present work polycaprolactone (PCL), a newly remarkable biocompatible and biodegradable polymer, was employed as a matrix and hydroxyapatite nanoparticles and nanorods were used as a reinforcement element of the composite. HA/PCL nanocomposites were synthesized by three new in-situ sol-gel processes using a diverse range of phosphorus and... 

This study investigates the effect of titanium dioxide and magnesium oxide additives on hydroxyapatite synthesized by sol-gel and composite with the predominant phase of hydroxyapatite by in situ method to improve mechanical properties. Scaffold samples were synthesized with nanometer-sized hydroxyapatite and composite powder particles by gel casting and sintered at 1200 ° C. Then, to evaluate the synthesized powders, simultaneous thermal analysis (STA), X-ray diffraction test, FTIR test, FESEM, EDS, and MAP analysis were used. Also, to evaluate the mechanical properties of the scaffolds, a compressive test was used, and to evaluate the scaffolds' density, the Archimedes method was used.... 

Successful treatment of bone infections is a major orthopedic challenge due to the physiological and anatomical features of bone. In this project, we prepared a drug delivery system with injectable and biodegradable polysaccharide agar containing alginate, polyvinyl alcohol and hydroxyapatite nanocarriers composite microspheres. Alginate and polyvinyl alcohol composite microspheres are crosslinked by calcium and freeze-thawing technique. Using the freeze thawing process for polyvinyl alcohol crosslinking, in addition to alginate crosslinking, improved hydrogel swelling behavior and enhanced drug loading and thus slowed drug release, drug loading increased with increasing PVA percentage from ... 

Bone scaffolds are used to regenerate bone tissue and accelerate bone healing, for this purpose, an attempt was made to prepare biocompatible, biodegradable, low toxicity and non-allergenic scaffolds to help increase osteogenesis and improve bone infections. A porous multi-component composite of chitosan, hydroxyapatite, graphene oxide functionalized with silver was made to make the desired scaffolds. At first, graphene oxide was functionalized by silver ions using silver nitrate. The structure of silver graphene oxide nanocomposite was confirmed by scanning electron microscope (SEM), Fourier infrared spectroscopy (FT-IR), and ultraviolet (UV-Visible) spectroscopy. In the next step, a... 

In this study, biocompatible ceramic coating, containing hydroxyapatite particles (HA), was successfully created by AC anodizing, on the surface of commercially pure titanium grades 2. Coating process basically consisted of three methods. In Method 1, samples were anodized in a salty electrolyte containing calcium – phosphate base and in method 2 samples were anodized as initial process, following cathodic polarisation deposition of HA particles. Finally in method 3, samples were anodized in an electrolyte containing of HA particles suspension.Parameters such as current density and time of anodizing process, in first procedure, and time of cathodic deposition process in second procedure, and... 

Plasma electrolyte oxidation process is one of the surface coating methods which is recommended to use as a surface preparation before applying the final coating on magnesium alloys due to its unique properties such as excellent adhesion.The aim of this study was to create an oxide layer on the AZ91 substrate and after optimizing the PEO coating conditions and choosing the best coating in order to increase adhesion and corrosion resistance, the composite coating of graphene oxide, hydroxyapatite and chitosan was applied by electrophoretic method. After studying the morphology of PEO oxide coating at current densities of 0.25, 0.35, 0.4, 0.5 and 0.6 amp/cm2 during times of 5 and 8 minutes, it...