جستجوی مقالات مرتبط با کلیدواژه "biocompatibility" در نشریات گروه "مواد و متالورژی"

In this study, intending to control the corrosion of magnesium and its clinical application, a double-layer coating of Hydroxyapatite- Poly lactic-co-glycolic acid was applied on Mg by means of the electrodeposition and the dip method, respectively. X-ray diffraction (XRD) and scanning electron microscopy (SEM) are used to characterize the phase and morphology of the coatings. The results show a homogeneous coating with a thickness of 20-30 µm. Potentiodynamic polarization of the samples revealed that the double-layer coating exhibited a significant increase in corrosion potential, ranging from -1.82 to -1.4 V, and a decrease in corrosion current, ranging from 2.3 to 0.37 µA/cm2. Moreover, the MTT assay of the samples revealed that the amount of cell proliferation in the vicinity of the 48-hour extract of magnesium samples with double-layer coating had increased, indicating a decrease in the amount of ions released from the surface of magnesium by applying this coating.

Magnesium and its alloys are very suitable for making implants in physiological environments such as the human body from the point of view of being biodegradable, and they also have a hardness close to the bone. In addition, the characteristics of magnesium include lightweight, high strength, and good biocompatibility, which has created a tremendous change in the field of medicine for the new generation of biomaterials. However, magnesium alloys are associated with high degradation due to the release of hydrogen gas and the improvement of the surrounding tissues. Magnesium implants lose their mechanical integrity during the healing period before the bone heals due to the high degradation process. Various methods and techniques have been proposed to control the amount of magnesium degradation to acceptable levels. This article discusses an overview of the types of conversion coatings, effective methods to increase the quality of these coatings, and the factors affecting the performance of conversion coatings in improving the corrosion resistance of magnesium alloys. Among the different approaches, chemical conversion coatings are the most simple and cost-effective method, which even can remove the weak points of components with complex designs such as implants and stents. The conversion coatings are uniform and very sticky, and the expected characteristics of the coating can be obtained easily by changing the temperature, pH of the bath, and other compelling features. In this research, the types of conversion coatings and the strengths and weaknesses of each of these coatings have been investigated.

Cardiovascular diseases, including ischemic heart disease and stroke, are responsible for nearly 25% of all deaths worldwide. Globally, their prevalence continues to increase, despite enormous progress in cardiovascular diagnostics and therapy. For therapeutic and regenerative purposes, biomaterials promise solutions with multiple advantages over synthetic materials. Furthermore, their easy availability as nanoformulations recommends their application as drug carriers or protective nanoshells improving the biocompatibility of imaging agents. For example, compared to traditional drug delivery methods, nano-drug delivery introduces different ligands into corresponding nanocarriers according to pathological mechanisms and different therapeutic strategies to directly target the lesion site. This strategy more effectively targets the atherosclerotic plaque area and increases drug concentration to improve myocardial blood flow.

Nanocomposites are used in biological research due to their unique properties like non-toxicity and biocompatibility. In this study, a new nanocomposite was prepared using polyurethane polymer, and the meaty middle part of the pomegranate which infixed with nano-silver particles.

The nanocomposites containing polyurethane polymer, meaty shortcut part of pomegranate fruit, silver nanoparticles, and ciprofloxacin (drug) were chemically synthesized. SEM photomicrographs confirmed the presence of spherically dispersed silver nanoparticles. The combination of polyurethane with different weight percentages of pomegranate broiler was studied.

The best performance for drug uptake (4.85 g/g) and release (0.45 g/l) was obtained using a combination of polyurethane polymer with 5 g of pomegranate middling meat, and 1 g of silver nanoparticles (NC3). SEM analysis determined the morphology and dispersion of nanoparticles. FTIR and XRD analysis showed specific peaks (at 2-thetas of 27.01, 38.103, 44.374, 64.541) of silver indicating successful synthesis of the nanocomposites. By studying the particle size distribution (PSD) of silver nanoparticles, SEM image analyses and XRD crystalline size analysis showed that there was a very good match between these two PSDs. This indicates the high dispersion of nanoparticles in composite paste without agglomeration, which was the main reason for the high efficiency of nanocomposite in drug adsorption and dispersion in an aqueous environment. The soluble calibration curve with specified percentages of this drug was used to measure the quantitative dissolution of ciprofloxacin. The maximum wavelength of ciprofloxacin absorption was 270 nm in UV-Vis spectrophotometry analysis.

Considering the high importance of pure titanium in the medical industry and the weak mechanical and physical properties of this metal, in this research, in order to develop mechanical properties and at the same time improve biological properties, pure titanium composite reinforced with regenerated graphene oxide nanoparticles using the method SPS was fabricated and subjected to severe plastic deformation at room temperature by a simple shear extrusion method. The effect of plasma sintering, severe plastic deformation process and placement in a body simulating solution on changes in the mechanical, corrosion and biological properties of this titanium grade was investigated. As a result of adding 0.1% by weight of RGO to pure titanium and then fine-granulating the produced composite structure, with a simple shear extrusion step, the amount of calcium (bone formation) in the body and after 28 days in the body simulating solution, more and it has a higher quality than the pure sintered sample. Also, the tensile strength of this sample after 28 days in the body simulating solution was higher than the pure sintered sample, so that the tensile strength of the pure sample and the sample with fine-grained RGO were recorded as 750 and 1089.4 MPa, respectively.

Abstract     Nowadays, magnesium alloys such as a new generation of biodegradable materials have been noticed by researchers. In this study, to the sanitation of biodegradability and biocompatibility of magnesium alloys, TiO2/MgO dual layer coating was formed by magnetron sputtering on AZ91 and the microstructure, corrosion behavior and biocompatibility properties of coating were investigated. The coating microstructure was studied via field emission scanning electron microscopy (FESEM) X-ray diffraction (XRD). The corrosion resistance of the substrate and coated sample was evaluated by electrochemical polarization test in simulated body solution (SBF). To evaluate biocompatibility MTT and cell viability tests were used. The results showed that the corrosion potential after the surface coating with TiO2/ MgO was more positive, changing from 1.532 V for the uncoated sample to 1.436 V for the coated sample.. The coating was observed in quasi-spherical morphology with MgTi2O5 and MgTiO3 phases in interface of coating and substrate and two layers of coating too according to XRD analysis results. The results of the biocompatibility tests also showed that the viability of the osteoblastic cells on the coated sample increased compared to substrate.

Improved magnetic characters of graphene oxides besides its unique biocompatibility make this compound as a theranostics agent could be so practical in the medicine fields. Oxygen functionalities with disturbing the symmetry of graphene sublattices could induce magnetic moments and improve magnetic properties in these structures . While that, vacancies and distortions, created by oxygen release, are also considered as factor disturbing the symmetry of graphene structure and increase its magnetic characters. To consider the effect of oxygen functionalities and deoxygenated defects on the magnetic properties of graphene structure, graphene oxide was synthesized by modified-Hummer method, reduced by distilled water and finally annealed in Argon furnaces. The variation in oxygen bond intensities and level of structural defects was evaluated by Fourier Inferred Transformer and Raman spectroscopy, respectively. And then, their results was matched by vibrating sample magnetometer. The result revealed that the competition between the effect of oxygen groups and deoxygenated defects on the graphene symmetry determinates the magnetic properties of RGOs.