Hydroxyapatite (Ca10(PO4)6(OH)2) with the hexagonal crystal structure is the only identifiable mineral phase of bone. In this work, magnesium ferrite-hydroxyapatite nanocomposites were synthesized for the purpose of medical applications. The first step of this work is the synthesis of mesoporous hydroxyapatite nanorods via co-precipitation method in combination with micelles template. Non-ionic surfactant Pluronic P123 was used as a micelles template. At the second step, magnesium ferrite-hydroxyapatite nanocomposites were synthesized by the sonochemical method. The crystal structure of nanopowders was determined using X-ray diffraction pattern. Transmission electron microscopy was also applied for the morphology of the samples. From TEM image of the nanocomposite, it was observed that magnesium ferrite nanopaticles have spherical shape with diameter of about 8 nm on the surface of hydroxyapatite nanorods. Hysteresis loops (M-H) of magnesium ferrite nanoparticles and magnesium ferrite-hydroxyapatite nanocomposites were measured at room temperature by a vibrating sample magnetometer. The results revealed the superparamagnetic behavior of the produced nanostructures.

Magnetic hydroxyapatite nanoparticles (Fe3O4/HAP) are prepared in the present work to remove uranyl ions via copercipitation method for the first time. The sorbent was prepared with the weight ratio of magnetic nanoparticles to hydroxyapatite (Fe3O4/HAP) as (1: 1), (1: 2), (1: 3), and (1: 5). After finding physical, chemical, and magnetic features, their ability to absorb uranyl ions was examined via UV-Vis method, measuring the absorbance of element complex with arsenazo (III). The effects of parameters such as temperature, pH, contact time, rate of the adsorbent, the concentration of uranyl, and the effects of interference of other ions on the removal of uranyl were analyzed. Also, the experiments showed that the highest rate of uranyl was absorbed by using 0. 015 g Fe3O4/HAP (1: 5) during 150 min at pH equal to 7. The prepared nanoparticles in 17±, 2 nm could absorb uranyl in the concentration range of 0. 2-100 ppm, eliminating over 96% of uranyl. The absorbing capability of 99. 82 mg/g was obtained at 25°, C. The results indicate the high potential of the prepared nano-particles in absorbing and eliminating uranyl and show its capability in the waste water containing uranyl.

IntroductionEnvironmental pollution by heavy metals is one of the most commonly-encountered problems in many areas in which biological controls have not been implemented. As these metals are non-biodegradable, they remain in the nature for a long time, and through deep percolation into underground water they can cause degradation of ecosystems. The uptake of these elements by plants and their inclusion in the chain of human and animal food is a great risk for the environment and the human being health. Due to non-biodegradable property of Cadmium and some other toxic heavy metals, these metals remain in the environment for a long time. Cadmium is one of the most toxic heavy metals and it has been reported to cause renal dysfunction.

Nanocrystalline Magnetic Hydroxyapatite (MHAp) was synthesized through co-precipitation method and the subsequent heat treatment. Phase analysis, particle morphology, chemical bonding, and magnetic properties were studied using XRD, FESEM, FTIR, and VSM, respectively. The XRD results showed that MHAp was formed by heat treatment at 1100 ° C. The samples heat-treated at 500 and 1100 ° C incorporated a plate-like morphology with a mean crystallite size of 11. 7 and 59. 9 nm, respectively. In addition, the VSM results indicated that the synthesized MHAp was characterized by magnetic features after heat treatment. According to the findings in this study, the coercive field (Hc), saturation magnetization (Ms), and magnetism stayed (Mr) were 0. 175 kOe, 0. 00147, and 0. 02615 emug-1, respectively, in-10 to 10 kOe magnetic field. The growth kinetics of the MHAp was alo studied. According to the results, the growth activation energies for low and high temperatures were 45. 51 and 67. 33 kJ/mol, respectively. Owing to several properties already proven, the MHAp powder was successfully synthesized.

Herein, impedimetric determination of uranyl ions (UO22+) by using a modified magnetically carbon paste electrode (MCPE) with hydroxyapatite magnetic nanoparticles (MNP/HAP) was reported for the first time. Firstly, magnetic nanoparticles were synthesized and then hydroxyapatite nanoparticles were precipitated on them via the chemical precipitation method. After that, the MCPE electrode was modified by MNP/HAP to collect UO22+ from an aqueous solution. Modification of the electrode and its interaction with UO22+ ions were studied by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) in the presence of a Fe[(CN)6]3-/4- and PBQ/H2Q, as a redox probe. Electrochemical impedance change against the concentration of UO22+ ions in the presence of electrochemical probes was selected as an analytical signal of this procedure. Optimized response for modified electrode with 100 µg MNP/HAP was observed after preconcentration of UO22+ for 30 min at pH 7, and for 35 min at pH 6 for Fe[(CN)6]3-/4- and PBQ/H2Q as a redox probe, respectively. The applicability of the impedimetric method in the determination of uranyl by using the proposed electrode was shown by drawing a linear calibration curve in the concentration range between 1×10-10 to 4×10-4 M of UO22+ in the presence of both probes. Detection limits as 7.58×10-11 M and 9.12×10-11 M and relative standard deviation (RSD) for n = 5 as %0.82 and % 1.05 were observed for Fe[(CN)6]3-/4- and PBQ/H2Q as a redox probe, respectively.

Background and purpose: Magnetite hydroxyapatite (m-Hap) as a magnetic nano-adsorbent was synthesized for the removal of tetracycline (TC) from aqueous solutions.Materials and methods: The properties of m-Hap were investigated by scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR). Factors affecting the adsorption of TC including pH (3-10), adsorbent dosage (0.1-5 g/L), contact time (5-120 min) and initial concentration of TC (10-25 mg/L) were investigated. The effect of adsorbent on the removal of tetracycline from real wastewater was also studied.Results: The nanocomposite was almost spherical in shape and about 20-30 nm in diameter. In optimum conditions more than 99% of TC was removed (contact time 60 min, adsorbent dose 1g/L, and pH 7.5). The equilibrium data were well fitted into Langmuir model (R2=0.977) and the maximum adsorption capacity was 64.4 mg g-1 at pH 7.5 and 298 K. Adsorption experiments on hospital wastewater indicated a slight decrease in adsorption removal of TC (85%).Conclusion: This study showed that the magnetic Hydroxyapatite nanoparticles could be used as a highly efficient and promising adsorbent in water and wastewater treatment systems.

Core–shell magnetosensitive nanocomposites (NC) based on single-domain magnetite (Fe3O4, core), with a shell consisting of hydroxyapatite (HA) and cytotoxic drug doxorubicin (DOX) layers have been synthesized. The processes of DOX adsorption on Fe3O4/HA surface from physiologic solution have been studied. DOX release into saline was found to decrease with growing of its quantity on NC surface. It has been determined that cytotoxic influence and antiproliferative activity of Fe3O4/HA/DOX NC with respect toSaccharomyces cerevisiae cells are characteristic for interaction of these cells with a free form of doxorubicin. Magnetic liquids containing Fe3O4/HA/ DOX NC stabilized by sodium oleate and polyethylene glycol were prepared and investigated. It is shown that using the ensemble of Fe3O4 carriers as a superparamagnetic probe, the Langevin’s paramagnetism theory, and the values of density of nanocomposite constituents, one can evaluate the size parameters of their shell, which has been corroborated by independent measurements of specific surface area of nanostructures and kinetic stability of the corresponding magnetic liquids. The obtained results may be useful for development and optimization of novel forms of magnetocarried medical remedies of targeted delivery and adsorbents based on nanocomposites of superparamagnetic core–shell type with multilevel nanoarchitecture, as well as for determination and control of the size parameters of its components.

This study focuses on the physical, magnetic, biological and antibacterial behavior of cobalt-doped hydroxyapatite (HAp) powder samples. Pure and cobalt-doped HAp nanoparticles were synthesized by hydrothermal method. Calcium nitrate, di-ammonium hydrogen phosphate and cobalt nitrate were used as precursor materials. The synthesized powders were characterized using x-ray diffraction pattern (XRD), fourier transform infrared spectroscopy (FTIR), eld emission scanning electron microscopy (FESEM), vibrating sample magnetometer (VSM), raman spectroscopy as well as MTT assay and cell adhesion test. Disc diffusion method was used to investigate antibacterial activity of the samples. The results conrmed the substitution of Ca by Co ions in the HAp lattice. In addition, this substitution induced size reduction and morphology change in HAp particles. All cobalt substituted HAp powder samples displayed paramagnetic properties, as opposed to the diamagnetic behavior observed in the pure HAp samples. In addition, these nanoparticles exhibited cell adhesion, cell viability and antibacterial activity against S. aureus bacteria.

Synthesis of HAp is of considerable interest because of its similarity to mineral component of bone. It has good biocompatibility and bioactivity for bone tissue therapy. In this project, we looked at the effect of calcium substitution with cobalt divalent cation on the structure and magnetic property of HAp. Cobalt- doped HAp nanoparticles was synthesized via hydrothermal condition. First, Calcium nitrate and Cobalt nitrate was mixed. Then diammonium hydrogen phosphate was added drop by drop and finally Co-HAp was precipitated from the solution. The precipitate was heated at 200°C under hydrothermal condition. XRD pattern analysis verified the substitution of cobalt in HAp structure by showing a shift in the peak positions in the pattern. Furthermore, broadening and reduction in the peak intensities of the peaks with cobalt substitution was also observed in this study. The presence of functional groups related to HAp structure (PO4 3-, OH-) were confirmed by FTIR analysis. The size and morphology of nanoparticle HAp particles were evaluated by FESEM analysis. Calcium substitution with cobalt induced size reduction and morphology change in HAp particles. VSM analysis was carried out to investigate the magnetization of HAp and Co-HAp nanoparticles. The results showed that cobalt substituted nanoparticles displayed paramagnetic properties, as opposed to the diamagnetism of pure HAp. Cobalt doped HAp, a biomaterial with magnetic properties, could be used in a variety of biomedical applications, including magnetic imaging, drug delivery and hyperthermia based cancer treatment.