Synthesis of mesoporous CuFe2O4@SiO2 core-shell nanocomposite for simultaneous drug release and hyperthermia applications

In the present work, magnetic CuFe₂O₄ nanoparticles were synthesized through a sol-gel combustion. The synthesized CuFe₂O₄ were coated with mesoporous SiO₂. The synthesized CuFe₂O₄@SiO₂ nanocomposite was investigated for drug release and hyperthermia applications. The products were studied by X-ray diffraction analysis, Fourier-transform infrared spectroscopy, simultaneous thermal analysis, Brunauer-Emmett-Teller surface area, scanning electron microscopy, transmission electron microscopy, and vibrating sample magnetometer. TEM images showed the formation of silica coating with a thickness of 14 nm around copper ferrite. The surface area of the samples increases from 2.59 to 199.2 m²/g after the surface modification of ferrites nanoparticles with silica. The CuFe₂O₄@SiO₂ exhibited high ibuprofen loading and controlled drug release. These improvements resulted from the nanocomposite's mesoporous structure and high surface area. Coating CuFe₂O₄ nanoparticles with mesoporous silica reduced the cytotoxicity and improved drug release properties. However, this coating reduced the hyperthermia ability. The formed CuFe₂O₄@SiO₂ nanocomposites show high potential for simultaneous drug release and hyperthermia applications with prospective use for biomedical applications.     

Antibacterial and magnetic response of site-specific cobalt incorporated hydroxyapatite

Hydroxyapatite [HA, Ca₁₀(PO₄)₆(OH)₂] based ceramics are a potential candidate for orthopedic implants, bone cements, and bioactive coating over metallic implants due to their compositional similarities [Ca/P = 1.67] with human bone. Cobalt doping in HA can greatly enhance angiogenesis and vascularization along with incorporating antimicrobial properties to HA. For the first time, this work reports the importance of Co doping sites on biological and magnetic properties of HA. In the current work, Co doing in HA has been carried out according to the chemical formula Ca₁₀(PO₄)₆Co_x(OH)_2-α and Ca_10-x Co_x(PO₄)₆(OH)₂, (x = 0, 0.2 and 0.3) to assess the correlation of individual Co incorporation sites on crystal chemistry, cytotoxicity, magnetic properties, ion leaching and antibacterial efficacy. Dependence of antibacterial efficacy on different doping sites revealed that cytocompatible Co doped HA is antibacterial against E. coli, and S. aureus mainly after substitution of Co in Ca site. Additionally, a minor antibacterial effect has been noticed after Co doping in OH channels. Interestingly, the Ca substituted Co doped HA shows Co leaching up to ∼758 ppb (obtained from inductively coupled plasma-mass spectrometry), which comes to only ∼27 ppb after incorporating Co in OH channel. This higher Co leaching (when doped at Ca site in comparison to that at OH channels) is the major cause of better antibacterial efficacy. Vibrating sample magnetometer measurements showed that the order of m_r and m_s values significantly changes after altering the doping sites, due to change in local Co environment. Thus, this work proves that different doping sites of Co doped HA can greatly enhance its antibacterial properties with significant changes in crystallographic and magnetic properties, which make Co doped HA an ideal choice as a bone replacement material or drug delivery agent with tailored properties depending on the doping sites.     

Mechanosynthesis of nanostructured magnetic Ni-Zn ferrite

Nanocrystalline Ni-Zn ferrite (NiZnFe₂O₄) was directly produced by high energy ball milling of stoichiometric mixture of ZnO, NiO, Fe₂O₃ powders. X-ray powder diffractometry (XRD), scanning electron microscopy (SEM), simultaneous thermal analysing (STA), Fourier transform infrared spectroscopy (FTIR) and vibrating sample magnetometer (VSM) were carried out to characterize the structural, chemical and magnetic aspects of NiZnFe₂O₄ compound. The formation of NiZnFe₂O₄ phase appeared to involve two stages; development of Zn ferrite by diffusion of ZnO in Fe₂O₃ followed by diffusion of NiO in Zn ferrite to form Ni-Zn ferrite. The crystallite size of final product after 60 h of ball milling time was estimated to be 18 nm which increased to 45 nm after annealing at 800 °C for 4 h. After annealing of ball milled powders, the saturation magnetization was increased and coercivity was decreased as lattice defects and internal strain reduced.     

介孔羟基磷灰石的合成及药物释放性能研究

本文采用水热合成法,制备出介孔羟基磷灰石,该材料具有较高比表面积和较大的孔容,药物缓释性能测试表明,材料具有较高的药物组装率和较好药物缓释性能,因此,可以作为药物缓释载体,从而更好地实现对骨组织的修复。     

Synthesis and magneto-structural properties of chitosan coated ultrafine cobalt ferrite nanoparticles for magnetic fluid hyperthermia in viscous medium

AC induction heating mediated magnetic fluid hyperthermia of superparamagnetic nanoparticles (MNPs) is being widely explored for localized thermo-therapy of tumours. One of the primary hindrances for rapid adaptation of this technique is the loss of heating efficiency when the MNPs are placed within the viscous tissue medium, which necessitates undesired increase in MNP concentrations or exposure time during practical applications. With an objective to mitigate this, here we report the viscosity independent magnetic hyperthermia properties of biocompatible ultrafine (average size ～ 2.5 nm) chitosan-coated superparamagnetic CoFe₂O₄ MNPs synthesized using a low-cost co-precipitation technique. The presence of the chitosan coating is confirmed from Fourier transform infrared and X-ray photoelectron spectroscopy. The superparamagnetic nature of the synthesized MNPs at 300 K is confirmed from Mössbauer spectroscopy, isothermal and temperature dependent magnetization studies. Experimental findings indicate a higher field-induced heating efficiency for the chitosan-coated MNPs due to superior colloidal stability. The ultrafine size, combined with higher anisotropy energy density, results in viscosity independent Nèel relaxation-dominated magneto-thermal energy conversion for the CoFe₂O₄ MNPs. Experimental results reveal negligible loss of heating efficiency due to partial abrogation of Brownian relaxation when the chitosan-coated MNPs are immobilized in a tissue-equivalent agar medium, which is beneficial for practical applications. The heating efficiency of ～72.1 ± 2.8 W/g_Fe (at 33.1 kA/m and 126 kHz), obtained in the present study for the chitosan-coated MNPs, is higher than the previously documented values for ultrafine CoFe₂O₄ MNPs, which is useful for reducing the exposure time during practical applications. Further, the chitosan coating rendered the ultrafine CoFe₂O₄ MNPs bio-compatible against L929 cell line. The satisfactory magnetic fluid hyperthermia efficiency, negligible room temperature coercivity, retention of the field-induced heating efficiency in tissue-equivalent agar medium due to Nèel-dominated relaxation dynamics and superior biocompatibility, make the chitosan-coated ultrafine CoFe₂O₄ MNPs an attractive candidate for practical MFH applications.     

Study of microstructural,mechanical, and biomedical properties of zirconia/hydroxyapatite ceramic composites

In this study, hydroxyapatite was obtained by the sol-gel method, and zirconia/hydroxyapatite composites (YSZ/HAp) were produced with weight proportions of 95/5, 90/10, 85/15, and 80/20, respectively. The samples were characterized by X-ray diffraction (XRD), Archimedes' principle, Fourier-transform infrared spectroscopy (FT-IR), Vickers microhardness, scanning electron microscopy (SEM) and field emission scanning electron microscopy (FESEM). The calvarial critical-sized defect experimental model in rats was used to evaluate the biological interaction between YSZ/HAp scaffolds and bone tissue by Micro CT analysis. The XRD patterns of composites showed the major intensity of the zirconia phase and lower intensity of the hydroxyapatite phase, but the FT-IR analysis confirmed the presence of hydroxyapatite. Dense composite materials were verified by way of the Archimedes’ principle, where the YSZ/HAp 85/15 sample had lower apparent porosity (0.60%) and water absorption (0.10%). Vickers microhardness showed that composite material hardness decreased with the increase of hydroxyapatite, varying from 1367.43 to 711.37 HV. SEM images were possible to quantify the crack sizes in the indentations and to identify the elements presents by EDS, while FESEM was applied to analyze the morphology of the powders and microstructure of the composites. Among the composite studied, YSZ/HAp 85/15 and YSZ/HAp 80/20 samples were the compositions that demonstrated the best mechanical behavior with a fracture toughness of 9.2 and 9.3 MPa m^1/2, respectively. The YSZ/HAp scaffold showed an interaction with bone tissue. The percent bone volume (BV/TV, p < 0.001) and bone mineral density (BMD, p < 0.01) were significantly increased in Zirconia/hydroxyapatite scaffold.     

Synthesis and potential applications of silicon carbide nanomaterials / nanocomposites

The rapid development of nanotechnologies has accelerated the research in silicon carbide (SiC) nanomaterial synthesis and application. SiC nanomaterials have unique chemical and physical properties, such as distinctive electronic and optical properties, good chemical resistance, high thermal stability, and low dimensionality. These properties lead to a wide range of applications. The progress in SiC nanomaterials in recent years is significant, but a review of the progress is lacking. This article is designed to fill the gap. The review first summarizes various methods for preparing different SiC nanomaterials/nanocomposites, including the carbothermal method, chemical vapor deposition method, and other synthesis techniques using unconventional energy sources such as microwave, plasma, solar energy, and neutron irradiation. Discussion is then made on the significant applications of the SiC nanomaterials/nanocomposites, especially in sensors, catalyst supports, energy storage materials, structural reinforcement, and semiconductor materials. Finally, the conclusion of this review is made with the possible future development trends.     

Synthesis and characterization of Tb/Gd dual-doped multifunctional hydroxyapatite nanoparticles

Tb³⁺/Gd³⁺ dual-doped multifunctional hydroxyapatite (Tb³⁺/Gd³⁺-HAp) nanoparticles with magnetic and luminescent properties were prepared by the co-precipitation method using CaCl₂ and Na₂HPO₄·12H₂O as raw materials and CTAB as a template in alkaline conditions. The products were characterized by X-ray diffractometry (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM). Single hexagonal phase Tb³⁺/Gd³⁺-HAp nanoparticles were obtained by the co-precipitation method and the products were sphere-like morphology with particle sizes ranging from 40 to 100 nm. Crystallinity degree of the products decreased with the Tb³⁺/Gd³⁺ substitute increasing. Photoluminescence (PL) and magnetic properties of the products were also investigated. The results show Tb³⁺/Gd³⁺-HAp nanoparticles are endowed with strong luminescence at 544 nm and prominent paramagnetic behavior, allowing their potential applications in biological labeling. Gd³⁺ ions sensitize the ⁵D₄-⁷F₅ transition emission of Tb³⁺ ions in HAp nanoparticles, and the PL emission intensity increases along with increasing concentration of Gd³⁺ ions. Concentration quenching occurs when the Gd³⁺ concentration exceeds 10 mol%. The magnetization level of Tb³⁺/Gd³⁺-HAp increased steadily with the doping concentration of Gd³⁺ ions.     

Microwave-assisted solution synthesis,microwave sintering and magnetic properties of cobalt ferrite

A simple, soft, and fast microwave-assisted hydrothermal method was used for the preparation of nanocrystalline cobalt ferrite powders from commercially-available Fe(NO₃)₃?9H₂O, Co(NO₃)₂?6H₂O, ammonium hydroxide, and tetrapropylammonium hydroxide (TPAH). The synthesis was conducted in a sealed-vessel microwave reactor specifically designed for synthetic applications, and the resulting products were characterized by XRD, FE-SEM, TEM, and HR-TEM. After a systematic study of the influence of the microwave variables (temperature, reaction time and nature of the bases), highly crystalline CoFe₂O₄ nanoparticles with a high uniformity in morphology and size, were directly obtained by heating at 130?°C for 20?min using the base TPAH. Dense ceramics of cobalt ferrite were prepared by non-conventional, microwave sintering of synthesized nanopowders at temperatures of 850–900?°C. The magnetic properties of both the nanopowders and the sintered specimens were determined in order to establish their feasibility as a permanent magnet.     

Synthesis of ordered mesoporous carbon/cobalt oxide nanocomposite for determination of glutathione

In the paper, a novel ordered mesoporous carbon/cobalt oxide nanocomposite (OMC–Co) was easily synthesized. After encapsulating cobalt oxide nanoparticles in the wall of the ordered mesoporous carbon (OMC), the mesostructure of the nanocomposite material remained highly ordered and intact. For the first time, OMC–Co material was used to modify the glassy carbon (GC) electrode, and the obtained OMC–Co/GC modified electrode showed strong electrocatalytic properties towards glutathione (GSH). The use of OMC–Co film to mediate the GSH oxidation exhibited remarkably strong and stable electrocatalytic response compared to that seen at OMC/GC electrode. These results showed that the electrocatalytic properties of OMC could be improved when the cobalt oxide nanoparticles were incorporated into this new material. A sensitive GSH sensor was developed based on the OMC–Co/GC electrode, which showed a high sensitivity and a remarkably low detection limit. Moreover, OMC–Co/GC modified electrode can be used for selective amperometric determination of GSH in the presence of glucose, dopamine (DA) and uric acid (UA).     

Effect of the thermal treatment on the magnetic and structural properties of cobalt ferrite particles

We herein report a study on the sol-gel synthesis of CoFe₂O₄ and the effect of thermal treatment on the product outcome. Xerogels treated at 750, 800 and 850 °C had their structural and magnetic properties thoroughly studied, in order to correlate their synthesis conditions to the positions in which the cations are inserted in the spinel structure. X-ray diffractograms exhibit reflections representative of the spinel structure and demonstrate that the thermal treatment does not affect the lattice parameters of the material. Mossbauer spectroscopy studies indicate a very low inversion degree in the synthesized spinels, which is very unusual for CoFe₂O₄. A maximum in coercivity of 1405.2 Oersted was achieved for the sample treated at 800 °C.     

Development of multifunctional cobalt ferrite/hydroxyapatite nanocomposites by microwave assisted wet precipitation method: A promising platform for synergistic chemo-hyperthermia therapy

Functional nanocomposites capable of multimodal therapy hold great potential to improve the efficiency of cancer therapy. Herein, we report a magnetic nanocomposite of cobalt ferrite/hydroxyapatite followed by loading a chemotherapeutic drug (5-fluorouracil, FU) to construct the intelligent drug delivery system and/or hyperthermia carrier. To do that, cobalt ferrite/hydroxyapatite nanocomposite was successfully synthesized by microwave assisted wet precipitation method, subsequently, FU loaded onto the formed composites through adsorption method. This nanocomposite exhibits ferromagnetic behaviour with a magnetic saturation value of approximately 2.5–8.2 emu/g. Upon alternating magnetic field, it could generate hyperthermia temperature within a short time (43°C in 4.5 min) and facilitate the release of encapsulated FU from the composite with enhanced release rate. These multifunctional carriers also demonstrate a noticeable proliferative activity against healthy fibroblast cells (L929) and suppressed growth against osteosarcoma cells (MG63). Therefore, this studied nanoplatform might be a promising candidate for synergistic chemo-hyperthermia therapy.     

Synthesis and properties of HA/ZnO/CNT nanocomposite

The goal of this study was to examine the tribomechanical properties of hydroxyapatite (HA)/ZnO and HA/ZnO/CNT composite ceramics (carbon nanotubes; with different ratios 0.5?wt%, 1.0?wt%, and 1.5?wt%). The composites were synthesized using the hydrothermal method in an autoclave. The structure and morphology of the composites were analyzed using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), energy-dispersive X-ray analysis (EDX) and transmission electron microscope (TEM). The consolidation process was performed by sintering the compounds at 1150?°C under an argon gas atmosphere. The effects of ZnO and CNT on the mechanical properties and wear resistance of the HA-nanoparticle-based ceramic composites were investigated using a Vickers hardness tester, nanoindentation, and reciprocating wear tester equipment. The nanohardness and elastic modulus of the sintered samples increased and the friction coefficient of the sintered samples decreased as the fraction of CNTs increased compared to the pure HA and HA/ZnO compounds. Furthermore, the wear loss of HA/ZnO/CNT composites decreased with the increase in the CNT content compared to the HA and HA/ZnO samples.     

Modeling and optimization of combustion synthesis for hydroxyapatite production

In this study, the combustion synthesis of hydroxyapatite was studied and optimized under controlled experimental conditions. The hydroxyapatite content, crystallinity and crystallite size were monitored under changes in type of fuel, pH or red/ox ratio, muffle temperature, and reaction time. The products were characterized by X-ray diffraction, refinement of crystalline phases by the Rietveld method, scanning electron microscopy, and infrared spectroscopy with the Fourier transform. The decomposition of hydroxyapatite, which was the major phase, produced beta tricalcium phosphate in all samples, as indicated by their diffractograms. Infrared spectroscopy analysis revealed the presence of b-type carbonate groups in the structure; thus, the synthesized compound has the following chemical formula: Ca_10-x (PO₄)_6-x (CO₃)_x (OH)_2-x, where 0 < x < 2, which corresponds to carbonated hydroxyapatite (CHAp). The combustion process was modeled using a first-degree polynomial, and we found that the interaction between time and temperature to be the most influential parameter. Optimization indicated that processing conditions at 650 °C for 30 min, using urea at pH = 2 and ϕ_e = 1.134, produced the best result in terms of HAp composition, yielding 89.25% wt.     

Sintering and mechanical properties of MgO-doped nanocrystalline hydroxyapatite

Hydroxyapatite (HA) has been extensively studied for its exceptional ability in promoting osseointegration as in bone graft substitute and biomimetic coating of prosthetic implants. However poor mechanical properties of HA, in particular its low fracture toughness, has made its widespread adaption in a number of biomedical applications challenging. Here we employ an optimized wet precipitation method to synthesize nanocrystalline HA with significantly improved mechanical properties. In addition doping by MgO is found to effectively suppress grain growth and enhance fracture toughness by nearly 50% while good densification and phase stability in all samples regardless of concentration of dopant are fully maintained. Microstructural analysis further suggests that the exceptionally superior mechanical properties can be explained by migration of MgO to grain boundaries where they transform the more common transgranular fracture into an intergranular mode. Our biodegradation tests also confirm that MgO-doped HA is indeed a suitable candidate for load bearing implants.     

Effect of fluoride additive on the mechanical properties of hydroxyapatite/alumina composites

The effect of fluoride additives on the mechanical properties of hydroxyapatite/alumina composites was investigated. When MgF₂ (5 vol%) was added to hydroxyapatite/alumina composites, the decomposition of hydroxyapatite was suppressed due to the substitution of F⁻ for OH⁻ in the crystal structure. Comparing two additives, such as MgF₂ and CaF₂, MgF₂ showed much more effective for the suppression of phase decomposition in the hydroxyapatite/alumina composites due to the enhanced substitution of F⁻ for OH⁻. In the case of MgF₂ addition, a relatively high-mechanical properties (flexural strength: ∼170 MPa; Vickers hardness: ∼7 GPa) was obtained compared to MgF₂-free composites.     

Design,fabrication, and magnetic properties of novel (Ni,Cr,Zr)-co-doped M-type barium ferrite ceramics

Multicomponent co-doping is an effective method to balance the counteracting magnetic properties of ferrite ceramics. In this work, novel (Ni,Cr,Zr)-co-doped M-type barium hexaferrites (BaFe_12-3xNi_xCr_xZr_xO₁₉, x = 0–0.8) were designed and synthesized by traditional solid-state reaction. Thermogravimetric analysis indicated that NiO would participate in the formation of secondary phase NiFe₂O₄ in the as-synthesized powder. Through traditional solid-state sintering, by using the synthesized pure-phase magnetic powders, almost full-dense ceramics were fabricated. Visual high-temperature deformation analysis revealed that there was no obvious difference in the sintering behavior and densification temperature of the ceramics with different compositional x, due to the low sintering activity of the as-synthesized magnetic powders. And X-ray diffraction analysis indicated that all the fabricated ceramics are of pure-phase M-type barium ferrite, and the lattice parameter c/a firstly increased as x raised up to 0.4 and then remained almost unchanged with further increased x, even if the lattice distortion became heavier. Microstructure examination revealed that the grain size monotonously decreased as the quantity of the substituent ions increased. The remnant magnetization and coercivity of the fabricated ceramics decreased monotonously as x increased, while the saturated magnetization could be maintained till the samples with x ≤ 0.4. Taking all the parameters into consideration, the samples with x = 0.4 might be a good candidate for transformer cores.     

The influence of cationic surfactant CTAB on optical,dielectric and magnetic properties of cobalt ferrite nanoparticles

In the present work, the influence of cationic surfactant CTAB (cetyltrimethylammonium bromide) on size, shape and coalescence behaviour of cobalt ferrite nanoparticles (CFNPs) synthesized via hydrothermal method is reported. Pure CFNPs show no additional peaks, whereas α-Fe₂O₃ phase is observed in CTAB added CFNPs upon annealing. FT-IR analysis confirms the formation of M − O vibrational bands (metal -oxygen) at tetrahedral A-site and octahedral B-site for both samples. SEM observations reveal less agglomeration and smaller particle size for surfactant added CFNPs. Raman spectral study confirms the formation of cubic spinel structure and Raman active modes of CTAB added CFNPs. UV–Vis spectra indicate a decrease in the energy band gap with annealing. The dielectric constant of surfactant added CFNPs decreases with increasing applied frequencies for both real and imaginary, but ac conductivity increases with increasing frequencies. Two sextet patterns of Fe³⁺ trivalent ions from tetrahedral and octahedral sites are observed in Mössbauer spectra. VSM study indicate the ferrimagnetic nature of CTAB added CFNPs. The electrochemical analysis reveals the pseudocapacitive nature of working electrode prepared by CTAB added CFNPs.     

Synthesis and characterization of polypyrrole/graphitic carbon nitride/niobium pentoxide nanocomposite for high-performance energy storage applications

Graphitic carbon nitride (GCN) has been employed as a supercapacitor electrode because of its high carbon-to-nitrogen ratio and flexible structure. However, its low surface area and poor conductivity continue to be obstacles for practical usage. GCN's electrochemical characteristics are enhanced by the hybrid structure it forms with polypyrrole and Nb₂O₅. The synthesized polypyrrole (Ppy)/GCN/niobium pentoxide (Nb₂O₅) (Ppy/GCN/Nb₂O₅) nanocomposite electrode was tested for supercapacitance by cyclic voltammetry (CV) and Alternating current impedance techniques in 6 M Potassium hydroxide(KOH) electrolyte. The Ppy/GCN/Nb₂O₅ is linked to a network of agglomerated GCN and Nb₂O₅ nanoparticles with additional spherical shapes. The specific capacitance of Ppy/GCN/Nb₂O₅ was determined to be 1177 Fg⁻¹ at a current density of 5 Ag⁻¹. The Ppy/GCN/Nb₂O₅ electrode in KOH has average specific energy and specific power densities of 33 Wh kg⁻¹ and 2991 W kg⁻¹, respectively. The electrode showed excellent capacitance-retention ability of 97% after 10,000 cycles. The results demonstrate the high stability and efficient performance of the Ppy/GCN/Nb₂O₅ electrode employed in supercapacitors. The performance of the Ppy/GCN/Nb₂O₅ electrode was found to be superior to those reported for other carbon-based materials.     

Synthesis and characterization of ceramic - polymer composites containing bioactive synthetic hydroxyapatite for biomedical applications

Presented research involved preparation of hydroxyapatite and synthesis of composites based on gelatin, albumin and polyvinylpyrrolidone (PVP) modified with the obtained compound. Hydroxyapatite was attained as a product of two-stage processing of pig bones. Applied procedure involved hydrolysis of the raw material in acidic environment and double calcination. Molar ratio Ca/P of hydroxyapatite has been determined and its chemical structure has been characterized using X-ray diffraction and FT-IR spectroscopy. Ratio Ca/P calculated on the basis of conducted research was 1.50?±?0.05. Thus prepared material met the ISO requirements, which assume that the Ca/P ratio should be in the range 1.5–2.0, which qualifies the material for further studies. Next, series of polymer matrix on the basis of gelatin, albumin and polyvinylpyrrolidone (PVP) has been synthesized and subjected to some analyzes. On the basis of the conducted studies, matrixes with the most favorable features such as desirable strength, flexibility and crosslinking degree were modified with previously prepared hydroxyapatite. Surface morphology and elemental composition of the composites have been analyzed using SEM-EDS method. Additionally, sorption capacity of modified composites and their behavior in simulated body fluids have been determined. Based on the conducted research it can be concluded that pig bones represent a good material for preparation of hydroxyapatite. Furthermore, composites based on proteins of natural origin modified with attained hydroxyapatite constitute a promising material that can be used for biomedical purposes.