Papers by Author: Nader Nezafati

Abstract: Basic drawbacks of calcium phosphate cements (CPCs) are the brittleness and low strength behavior which prohibit their use in many stress-bearing locations, unsupported defects, or reconstruction of thin bones. Recently, to solve these problems, researchers investigated the incorporation of fibers into CPCs to improve their strength. In the present study, various amounts of a highly bioactive glass fiber were incorporated into calcium phosphate bone cement. The obtained results showed that the compressive strength of the set cements without any fibers optimally increased by further addition of the fiber phase. Also, both the work-of-fracture and elastic modulus of the cement were considerably increased after applying the fibers in the cement composition. Herein, with the aim of using the reinforced-CPC as appropriate bone filler, the prepared sample was evaluated in vitro using simulated body fluid (SBF) and osteoblast cells. The samples showed significant enhancement in bioactivity within few days of immersion in SBF solution. Also, in vitro experiments with osteoblast cells indicated an appropriate penetration of the cells, and also the continuous increase in cell aggregation on the samples during the incubation time demonstrated the ability of the reinforced-CPC to support cell growth. Therefore, we concluded that this filler and strong reinforced-CPC may be beneficial to be used as bone fillers in surgical sites that are not freely accessible by open surgery or when using minimally invasive techniques.

Abstract: Today, porous nanocomposite scaffolds play a key role in tissue engineering approaches and new processing methods and materials are constantly being developed to cater for the wide range of specifications and requirements. In addition, providing a structural support while maintaining bioactivity is one of the most important goals for these scaffolds, i.e. applying bioceramic into polymeric structures, facilitating the formation of functional tissues. In the last few years, hydroxyapatite (HAp) has been widely investigated as scaffolding material, mainly for its ability to bond to both hard and soft tissues. In this research, new bioactive scaffolds were successfully developed using poly(ε-caprolactone) (PCL), cross-linked gelatin and nanoparticles of HAp. After synthesis of nano HAp powder via chemical precipitation technique, the nanocomposites were prepared through layer solvent casting and lamination techniques. According to the obtained results, the amount of ultimate stress, stiffness and elastic modulus increased by addition of PCL. Also, the in vitro biocompatibility and cytocompatibility of the scaffolds were tested using mesenchymal stem cells (MSCs), and cells found to be attached to the scaffold walls.

Abstract: Human beings are often infected by microorganisms in the living environment. Among various natural and inorganic substances, silver or silver ions have a powerful antibacterial activity. In the present study, the bioactivity and antibacterial activity of the SiO₂–CaO–P₂O₅–Ag₂O was compared with that of its ternary counterpart glass system (as a control sample) in vitro. The molar ratio of silver oxide in the bioactive glass composition was considered as different amount (0.5%, 1% and 2%). The surface characterization was evaluated after soaking in simulated body fluid (SBF). The sharpest apatite peak in X-ray diffraction (XRD) analyse after 7 days soaking in SBF was observed for 2% Ag sample (2%Ag-BG). Hence, the antibacterial effects of 2%Ag-BG sample against 2 gram negatives bacterium were examined by agar plate test. The result showed that the amount of silver did not prevent the HAp formation. Also, the antibacterial properties of 2%Ag-BG sample indicated near 100% bactericidal ratio (according to the width of antibacterial halo).