Sharif Digital Repository

In order to improve its biological properties, graphene oxide can be modified with hydrophilic polymers. Therefore, in this study, the surface of graphene oxide was modified with polyethylene glycol and albumin by covalent methods. In the subsequent step, paclitaxel which is a hydrophobic anticancer drug was loaded onto the surface of the functionalized graphene by π-π interactions. The synthesis of the nanocarrier and its interaction with paclitaxel were evaluated by FT-IR, CD, TEM, UV, AFM, DLS and fluorescence experiments. Release of the loaded drug from albumin-graphene conjugate was investigated at pH 5.4, 6.8 and 7.4  

In this research, the effect of various surface treatments including laser processing, grit blasting and anodizing on chemical structure, surface topography, and bioactivity of Ti-6Al-4V was investigated. Six groups of samples were prepared by a combination of two alternative laser processes, grit blasting and anodizing. Selected samples were first evaluated using microanalysis techniques and contact roughness testing and were then exposed to in vitro environment. Scanning electron microscopy was used to characterize the corresponding final surface morphologies. Weight measurement and atomic absorption tests were employed for determination of bioactivity limits of different surface... 

This investigation focused on a comparison between hydroxyapatite (HA) and carbon-nanotube-reinforced hydroxyapatite composite (CNTs/HA) coatings. The HA and CNTs/HA composite (with 5wt% CNTs) coatings were prepared with the sol-gel method on 316L stainless steel. Phase evaluation by means of XRD and Raman spectroscopy was performed on the HA and CNTs/HA composite coatings. The coatings were immersed in simulated body fluid (SBF) in order to evaluate the biological properties of the coatings. During the first week of immersion, the increase in the amount of Ca2+ precipitation in the SBF when CNTs/HA was used was lower than for the HA coatings. This behavior can be related to the difference... 

This study, for the first time, reports the synthesis of CuO- and Cu2O nanoparticles (NPs) using the Salvia hispanica extract by a high-gravity technique. The original green synthesis procedure led to the formation of nanoparticles with promising catalytic and biological properties. The synthesized nanoparticles were fully characterized and their catalytic activity was evaluated through a typical Azide-Alkyne Cycloaddition (AAC) reaction. The potential antibacterial activity against gram positive (S. aureus) and gram negative (E. coli) bacteria were investigated. It was shown that the antibacterial properties were independent of the NP morphology as well as of the texture of the synthesis... 

Titanium carbonated hydroxyapatite (Ti/CHA) nanobiocomposites have extensive biological applications due to the excellent biocompatibility and similar characteristics to the human bone. Ti/CHA nanobiocomposite has good biological properties but it suffer from diverse characteristics especially in hardness, Young's modulus, apparent porosity and relative density. This investigation is an attempt to propose the predictive models using gene expression programming (GEP) to estimate these characteristics. In this regards, GEP is used to model and compare the effect of practical variables including pressure, Ti/CHA contents and sintering temperature on their monitored properties. To achieve this... 

A flexible, porous and biocompatible titanium dioxide nanotubes (TNT) - polyurethane (PU) film has been produced as a new scaffold for artificial vascular grafts. Synergistic improvements in the properties of vertical TNT and PU was reached, including enhancements in their biocompatibility, mechanical strength, flexibility and porosity. Open-ended (OE) TNT-PU and close-ended (CE) TNT-PU films were synthesized and their mechanical and biological properties were compared with their pure PU counterparts. TNT were attached to PU with a new strategy. The resulting flexible structure was hydrophilic and super hydrophilic in OE-TNT-PU and CE-TNT-PU scaffolds, respectively. The gas leakage during... 

In this study, magnesium oxide (MgO) nanoparticles are incorporated on carbon nanotubes (CNTs) to reinforce Mg-3Zn-1Mn alloy (ZM31 alloy) by semi-powder metallurgy, followed by hot extrusion, with the purpose of improving the mechanical and biological properties of Mg-based alloy. The microstructural analysis of the nanocomposites indicated a reduction in grain size of Mg alloy with the incorporation of CNTs with a maximum reduction of 61% (ZM31/CNTs), with further reduction in grain size (68%) detected when MgO integrated CNTs composites (ZM31/MgO-CNTs). The compression characteristics of the composites indicate an increase in ultimate compressive strength of 36% and 44%, respectively, with... 

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) was employed as a matrix and hydroxyapatite nanorods were used as a reinforcement element of the composite. HA/PCL nanocomposites were synthesized by a new in-situ sol-gel process using low cost chemicals. Chemical and physical characteristics of the nanocomposite were studied by X-ray diffraction (XRD),... 

Salep, known as a biodegradable polysaccharide, is hydrolyzed and used as both a reducing agent and stabilizer for graphene oxide (GO). The functionalized reduced graphene oxide (f-rGO) is homogenously dispersed in an aqueous solution of poly(vinyl alcohol) (PVA). PVA based hydrogel and film nanocomposites are prepared and proposed as new biomaterials for tissue engineering applications. The mechanical properties of the film nanocomposites are investigated with varying content of f-rGO, glycerol and citric acid as a reinforcing agent, a plasticizer agent and a cross linking agent respectively. For the first time, chemically cross linked PVA hydrogels are synthesized using... 

For a successful repair and reconstruction of bladder tissue, fabrication of scaffolds with proper biochemical and biomechanical characteristics is necessary. Decellularized bladder tissue has been proposed in previous studies as a gold standard material for scaffold fabrication. However, weak mechanical properties of such a load-bearing tissue has remained a challenge. Incorporation of both biological and synthetic materials has been known as an effective strategy for improving mechanical and biological properties of the scaffolds. In the present work, a simple process was developed to fabricate hybrid hydrogel scaffolds with a biomimetic architecture from the natural urinary bladder... 

Progress in tissue engineering and regenerative medicine necessitates the use of novel materials with promising bio-surface for biomedical applications. In this work, TixNy thin films are applied on biological TC4 substrates in a mixed atmosphere of Ar and N2 via magnetron sputtering system for the protection of TC4 alloy. The effects of N/Ti ratio on the phase structure, growth orientation, contact angle, and the mechanical and corrosion performances of thin films are discussed by implementation of composition-microstructure-property interrelationships. The phase structure of TixNy thin films is changed from amorphous-like to single phase Ti2N structure with increasing N/Ti ratio. In the... 

Medical engineering advances in total joint replacements and societies’ rising demand for long-lasting materials have proven it essential to manufacture materials that are more similar to the original tissue in the fields of mechanical, tribological, and biological properties. Ultra-high molecular weight polyethylene (UHMWPE) is a polymer widely used in arthroplasty applications due to its biocompatibility, chemical stability, and reasonable mechanical properties; however, it still fails to entirely meet the standards of the hip joint implant. In this study, different concentrations of nanosized zirconia were added to UHMWPE and HAp matrix with an intended application in arthroplasty.... 

The present study focuses on simultaneous influence of graphene nanoplatelets (GNP) and hydroxyapatite (HAp) nanopowder on microstructural, wear, tensile and biofunctional behavior of UHMWPE based nanocomposites used in biomedical applications, with the aim to utilize GNP's mechanical strength and wear resistance, while benefitting from HAp's biocompatibility at the same time. 0.1, 0.5 and 1 wt% GNP with 10 wt% optimized concentration of HAp were added to the UHMWPE matrix through an easy two-step approach consisting of solvent mixing and ultrasonication in ethanol as a liquid media. The dried nanocomposite samples of powder were then hot pressed at an optimized temperature and pressure to... 

Medical engineering advances in total joint replacements and societies’ rising demand for long-lasting materials have proven it essential to manufacture materials that are more similar to the original tissue in the fields of mechanical, tribological, and biological properties. Ultra-high molecular weight polyethylene (UHMWPE) is a polymer widely used in arthroplasty applications due to its biocompatibility, chemical stability, and reasonable mechanical properties; however, it still fails to entirely meet the standards of the hip joint implant. In this study, different concentrations of nanosized zirconia were added to UHMWPE and HAp matrix with an intended application in arthroplasty.... 

Two main origins of failure for hard tissue replacements are structural loosening and prosthetic implant infections (PIIs). Bioinspired multifunctional TiO2 hierarchical micro/nanostructures of conical-shaped TiO2 (CTO), regular TiO2 nanotubes (RTO) and irregular TiO2 nanotubes (ITO) with tunable improved cell growth and inhibited bacteria adhesion were synthesized. CTO and ITO samples indicated superhydrophilicity with contact angles of less than 5°. The MTT assay demonstrated excellent biological performance for RTO and CTO sample with 98.1% and 103.1% of cell viability, respectively. The bridging force for osteoblast cell attachment onto the synthesized porous coatings was presented as a... 

In the present study, the effects of Sr and Mg were investigated on mechanical and biological properties of 58S bioactive glass (BG). SiO2-P2O5-CaO BG with different contents of Sr and Mg were synthesized via the sol-gel method and immersed in simulated body fluid (SBF) for several days to explore their biocompatibility. Precise analyses of the BG using X-ray powder diffraction, scanning electron microscopy, and transmission electron microscopy showed that the Mg-doped BG containing 8 wt % MgO possessed better biocompatibility. It was also found that mechanical properties of the BG could be improved by increasing the amounts of MgO and SrO. Both 5Sr-BG and 8Mg-BG samples did not exhibit any... 

In the last three decades, nanoclay fillers have been increasingly used to improve the mechanical, thermal, barrier and biological properties of the polymers. Nevertheless, incorporation of clays into the hydrophobic polymer matrices leads to the formation of the microcomposites with the minimal improvement in properties. To overcome the intrinsic incompatibility between the clays and the hydrophobic polymers, clay particles are organophilized using organic modifiers. The organic modifier should be thermodynamically miscible with the polymer. In the case of the composites prepared at high temperatures, the organic modifier should also have a high thermal stability to withstand the processing... 

Several pieces of research have been done on transition metal nanoparticles and their nanocomplexes as research on their physical and chemical properties and their relationship to biological features are of great importance. Among all their biological properties, the antibacterial and antimicrobial are especially important due to their high use for human needs. In this article, we will discuss the different synthesis and modification methods of silver (Ag) and gold (Au) nanoparticles and their physicochemical properties. We will also review some state-of-art studies and find the best relationship between the nanoparticles’ physicochemical properties and potential antimicrobial activity. The...