Crystalline selenite substituted carbonated hydroxyapatite nanorods: Synthesis,characterization, evaluation of bioactivity and cytotoxicity

Synthesis of pure and selenite substituted hydroxyapatites (HAP and Se‐HAP with 0.02–0.10 Se) by sol–gel method and evaluation of their morphological features, nature of functional groups, phase purity, in vitro bioactivity and cytotoxicity are addressed. Spectral studies confirm the incorporation of selenite into the HAP lattice, accompanied by an increase in CO₃^2? content to maintain the charge imbalance following replacement of P⁵⁺ with Se⁴⁺, thus making the formation of selenite substituted carbonated HAP. Selenite substitution in the HAP lattice has led to a higher crystallinity and increased the crystallite size. The morphology of HAP is changed from sphere to rod‐like structure upon substitution by selenite and the size of the rod is increased with an increase in the selenite content. Among the Se‐HAPs, a better in vitro bioactivity and cell viability are observed for 0.02 Se‐HAP and 0.04 Se‐HAP while the trend is reversed when the extent of selenite substitution becomes higher.     

Ni2P/Fe-HAP催化剂的表征及其苯酚加氢表面作用机理

以低品级羟基磷灰石(HAP)为原料,通过离子交换法合成载体Fe-HAP,然后用浸渍法制备出负载型Ni_2P/HAP和Ni_2P/Fe-HAP催化剂。通过BET、SEM、XRD、FTIR和TG等手段对催化剂进行了表征。Fe~(3+)的引入极大地提高了载体的比表面积,Ni_2P分散在Fe-HAP表面,热稳定性较好。以苯酚加氢制备环己酮为反应体系,在反应温度为150℃、压力为0.5 MPa、时间为3.5 h的条件下,对比了Ni_2P/HAP和Ni_2P/Fe-HAP催化剂的催化性能。结果发现,Ni_2P/Fe-HAP催化剂对苯酚的转化率为65.73%,环己酮选择性为85.47%,催化性能相对良好。     

Sodium dodecyl sulfate mediated microwave synthesis of biocompatible superparamagnetic mesoporous hydroxyapatite nanoparticles using black Chlamys varia seashell as a calcium source for biomedical applications

Designing biocompatible superparamagnetic mesoporous nanoparticles for advanced healthcare applications has received much attention. In this research, we have synthesized intrinsic mesoporous superparamagnetic hydroxyapatite (HAp) nanoparticles using bio-waste of black Chlamys varia seashell as a calcium source by sodium dodecyl sulfate (SDS)–enabled microwave-assisted synthesis approach. The synthesized Fe-doped HAp nanoparticles were characterized using various characterization techniques to know the phase purity and morphological features. The incorporation of Fe greatly affected the morphology of HAp nanoparticles without affecting their crystalline phase. Superparamagnetic behavior was observed with the incorporation of Fe in the HAp nanoparticles. Further, saturation magnetization was enhanced with higher incorporation of Fe ions. The cytotoxicity studies of the synthesized pure and Fe-doped HAp samples conducted using a human osteoblasts cell line (MG63), which indicated that Fe-doped HAp nanoparticles are biocompatible. Further, antibacterial activity analysis also confirmed their excellent antibacterial performance against different pathogens. Hence, SDS-enabled microwave-assisted synthesis approach using seashell as a calcium source would be a better approach for the production of intrinsic mesoporous superparamagnetic HAp nanoparticles for various biomedical applications, such as drug targeting, hyperthermia cancer therapy, and magnetic resonance imaging.     

Effect of concentration of Fe-dopant on the photoelectrochemical properties of Titania nanotube arrays

TiO₂ nanotubes have attracted great attention because of their photoelectrochemical activity. Metallic doping using a simple and rapid synthesizing approach can be a way to enhance this application. This paper describes a novel one-step anodization synthesis of Fe-doped TiO₂ nanotubes with various concentrations of iron doping. FESEM, XRD, and EDX were used to analyze the effect of doping concentration on the morphology, structure, and composition of the prepared samples respectively, and the results showed the formation of the anatase phase of TiO₂ nanotube arrays with Fe incorporation in the TiO₂ lattice. Although the Fe insertion in the TiO₂ lattice leads to better crystallinity, the non-uniformity in the morphology of doped samples suggests that adequate doping is required to maintain uniformity in the morphology. The absorption spectra of all the Fe-doped TiO₂ samples showed a red shift in their absorption edges compared to pristine TiO₂. This shift was observed more in the samples with higher doping concentrations. The photocurrent density of Fe-doped samples was observed to be significantly higher than that of the pristine TiO2 sample. This improvement was found to be concentration-dependent, with the best results being obtained from a sample doped at a level of 0.5%. The samples also showed high photostability, which, together with the increased photocurrent density, points to Fe-doped TiO₂ as a promising photoanode material.     

Mechanical characterization of high‐performance graphene oxide incorporated aligned fibroporous poly(carbonate urethane) membrane for potential biomedical applications

In this article, we report the development of graphene oxide (GO) reinforced electrospun poly(carbonate urethane) (PCU) nanocomposite membranes intended for biomedical applications. In this study, we aimed to improve the mechanical properties of PCU fibroporous electrospun membranes through fiber alignment and GO incorporation. Membranes with 1, 1.5, and 3% loadings of GO were evaluated for their morphology, mechanical properties, crystallinity, biocompatibility, and hemocompatibility. The mechanical properties were assessed under both static and dynamic conditions to explore the tensile characteristics and viscoelastic properties. The results show that GO presented a good dispersion and exfoliation in the PCU matrix, contributing to an increase in the mechanical performance. The static mechanical properties indicated a 55% increase in the tensile strength, a 127% increase in toughness for 1.5 wt % GO loading and the achievement of a maximum strength reinforcement efficiency value at the same loading. Crystallinity changes in membranes were examined by X‐ray diffraction analysis. In vitro cytotoxicity tests with L‐929 fibroblast cells and percentage hemolysis tests with fresh venous blood displayed the membranes to be cytocompatible with acceptable levels of hemolytic characteristics. Accordingly, these results highlight the potential of this mechanically improved composite membrane's application in the biomedical field. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41809.     

Fe3+掺杂NaTaO3纳米粒子的制备及光吸收机理

采用水热法合成了一系列铁离子掺杂NaTaO3 纳米粒子,研究了铁离子掺杂对宽禁带钽酸钠半导体光吸收性能的影响。XRD结果表明铁离子掺杂导致NaTaO3晶胞体积膨胀;紫外可见漫反射光谱表明铁离子掺杂引起钽酸钠吸收带边红移,并且随着铁离子掺杂浓度的增加,红移增大;密度泛函计算结果揭示,铁离子取代钽离子进入NaTaO3晶格会形成一个杂质能级,这个杂质能级主要由铁离子的3d轨道形成,是导致NaTaO3光吸收带边红移的原因。     

In-situ X-Ray observations and thermal modeling of unidirectional and bidirectional freeze casting

Freeze casting is a cost effective, efficient, and versatile technique capable of producing 3D structures with controlled pore shapes, orientation of crystals, and components' geometries in many porous materials. Freeze casting of hydroxyapatite (HAP) has been widely applied to bone tissue engineering due to HAP's biodegradable, biocompatible, and osteoconductive properties. It provides interconnected porous structures with a relatively high mechanical strength. However, there are still many unexplained phenomena and features because of the complexity of the process. This study demonstrates the use of X-ray synchrotron micro-radiography for providing time-resolved, in-situ imaging of ice crystal growth in the HAP suspensions. The experimental results show the ice crystal growth behavior under unidirectional and bidirectional freeze casting conditions. The finite element modeling (FEM) of the freeze casting process has been used to predict the development of ice front position and temperature gradient in the suspensions during the freeze casting.     

Characterization and biocompatibility of chestnut shell fiber–based composites with polyester

The structural, mechanical, biocompatibility, and biodegradability properties of composite materials formed of poly(butylene succinate) (PBS) and natural fiber (chestnut shell fiber; CSF) were evaluated. Maleic anhydride‐grafted poly(butylene succinate) (PBS‐g‐MA) and treated (crosslinked) CSF (TCSF) were used to improve the mechanical properties of PBS/CSF composites. The results show that PBS‐g‐MA/TCSF composites have superior mechanical properties compared with both pure PBS and PBS/CSF composites, which is attributed to better compatibility between the polymer and TCSF. Normal human foreskin fibroblasts (FBs) were seeded onto these two series of composites to characterize the biocompatibility. FB proliferation, collagen production, and cytotoxicity assays on the PBS/CSF series of composites exhibited superior results compared with those on the PBS‐g‐MA/TCSF composites. PBS‐g‐MA/TCSF was found to be more water resistant than PBS/CSF, and the weight loss of both the composites buried in soil compost indicated that both were biodegradable, especially at high levels of CSF substitution. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40730.     

Photoelectrochemical properties of iron (III)-doped TiO2 nanorods

Fe (iron)-doped TiO₂ nanorods were grown on fluorine doped tin oxide (FTO) substrates with various Fe doping concentrations using modified chemical bath deposition (M-CBD). We investigated the effects of Fe doping concentration on the morphological, structural, optical, and photoelectrochemical (PEC) properties of the TiO₂ nanorods. From this study, it was found that the PEC properties were mainly dependent on the morphological and optical properties of the Fe-doped TiO₂ nanorods. At low Fe doping concentration, the PEC properties were highly affected by the optical properties. On the other hand, the PEC properties were significantly affected by the morphological properties at high doping concentration. We observed a maximum photocurrent density of 0.48 mA/cm² at a Fe doping concentration of 2 at% from this study. In addition, the donor density and flat-band potential of the Fe doping concentration from the Mott–Schottky plot were analyzed.     

Enhancing photon absorption and conductivity of ZnO film by Fe doping: Experimental and first-principle perspectives

We study the optical and conductivity properties of Fe-doped ZnO (ZnO:Fe) film. ZnO and ZnO:Fe films (0.6 at. % and 1.2 at. % Fe concentration) were deposited using direct-current-unbalanced magnetron sputtering at room temperature. The presence of Fe dopant enhances the photon absorption of ZnO. The I–V and spectroscopic ellipsometry characteristic show that the electrical and optical conductivity of ZnO:Fe is increased. The first-principle calculation confirms the changes in the optical properties and conductivity due to Fe 3d states. The results show the role of Fe doping in modifying the optical and conductivity properties of ZnO film.     

Photoelectrochemical properties of Fe-doped TiO2 nanotube arrays fabricated by anodization

Ti–Fe alloys with Fe contents of 0.05, 0.5 and 1.0 wt% were obtained using the arc-melting method. Fe-doped TiO₂ nanotube arrays were prepared by anodizing Ti–Fe alloys in ethylene glycol solution containing 0.25 wt% NH₄F and 10 wt% H₂O. The microstructure, crystal structure and photoelectrochemical properties of the nanotube arrays were characterized using scanning electron microscopy, X-ray diffraction, UV–Vis diffuse reflectance spectroscopy and electrochemical analyzer. Results show that doping of 0.05 wt% Fe improves the photoelectrochemical properties of titania nanotube arrays significantly, whilst further increasing the Fe contents to 0.5 and 1.0 wt% degrades these properties. The external potential has a considerable influence on the photocurrent density at doping content of 0.5 wt% Fe.     

Application of strontium doped calcium polyphosphate bioceramic as scaffolds for bone tissue engineering

The critical success factors for bone tissue engineering in clinical applications are scaffolds. Ion doping is one of the most important methods to modify the properties of bioceramics for better angiogenesis abilities, biomechanical properties, and biocompatibility. This paper presents a novel ion doping method applied in calcium polyphosphate (CPP)-based bioceramic scaffolds substituted by strontium ions to form (SCPP) scaffolds for bone tissue regeneration. The microstructure and crystallization of the scaffolds were detected by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Degradation tests were assessed to evaluate the mechanical and chemical stabilities of SCPP in vitro. The cell biocompatibility was measured with respect to the cytotoxicity of the extractions of scaffolds. Bone implantation was performed to evaluate the biodegradability and osteoconductivity of the scaffolds, and the bone formation examined by using X-ray radiography. The results indicated that the obtained SCPP scaffolds had a single CPP phase. The SCPP scaffolds yielded a better degradation property than the pure CPP scaffold. The MTT assay and in vivo results reveal that the SCPP scaffolds exhibited a better cell biocompatibility and tissue biocompatibility than CPP and hydroxyapatite (HA) scaffolds. The in vivo immunohistochemistry staining for VEGF also showed that SCPP had a potential to promote the formation of angiogenesis and the regeneration of bone. SCPP scaffold could serve as a potential biomaterial with stimulating angiogenesis in bone tissue engineering and bone repair.     

Hydrothermal synthesis of uniform Fe-doped Gd(OH)3 nanorods and their magnetic properties: Phase conversion from paramagnetism to ferromagnetism

High quality pure and Fe-doped Gd(OH)₃ nanorods were fabricated through a template-free hydrothermal method for the first time. Analysis of XRD indicates that Fe³⁺ was incorporating in the interstitial sites rather than occupying the substitutional sites, forming pure hexagonal structure of Gd(OH)₃ without any other impurity phase. TEM characterizations show that all the samples perform uniform rod-like morphologies with similar diameter and length, which suggests that the Fe doping has little influence on the morphologies of samples. ICP and XPS spectra suggest that the dopant Fe³⁺ is incorporated into the inner body sites, not on the surface of nanorods. Magnetic studies show that the magnetic phase can be converted from paramagnetism to room-temperature ferromagnetism by doping Fe³⁺ ions into the Gd(OH)₃ nanorods. The saturation magnetization (Ms) is sensitive to the amount of Fe dopants, and the Ms for Fe_0.03Gd_0.97(OH)₃ nanorods reaches the maximum value of 0.184 emu/g. It is considered that the ferromagnetic ordering is possibly originated from the exchange interaction of Fe³⁺ through the oxygen vacancies, leading to the formation of point defect-mediated bound magnetic polarons (BMPs). Ruling out the affect of morphologies and secondary magnetic phase on the magnetic properties, the ferromagnetic ordering in uniform Fe-doped Gd(OH)₃ nanorods, in which the dopant Fe³⁺ is incorporated into the inner body sites of nanorods, are of great importance to deeply understand the rare earth-based DMS/DMD systems and have potential applications in spintronic devices.     

Hemocompatibility of electrospun halloysite nanotube‐ and carbon nanotube‐doped composite poly(lactic‐co‐glycolic acid) nanofibers

One of the major problems of nanofiber scaffold or other devices like cardiovascular or blood‐contacting medical devices is their weak mechanical properties and the lack of hemocompatibility of their surfaces. In this study, halloysite nanotubes (HNTs) and carbon nanotubes (CNTs) were incorporated within poly(lactic‐co‐glycolic acid) (PLGA) nanofibers and the mechanical property and hemocompatibility of both types of composite nanofibers with different doping levels were thoroughly investigated. The morphology and internal distribution of the doped nanotubes within the nanofibers were characterized using scanning electron microscopy and transmission electron microscopy. Mechanical properties of the electrospun nanofibers were tested using a material testing machine. The hemocompatibility of the composite nanofibers was examined through hemolytic and anticoagulant assay, respectively. We show that the doped HNTs or CNTs are distributed in the nanofibers with a coaxial manner and the incorporation of HNTs or CNTs does not significantly change the morphology of the PLGA nanofibers. Importantly, the incorporation of HNTs or CNTs within PLGA nanofibers significantly improves the mechanical property of PLGA nanofibers, and PLGA nanofibers with or without doping of the HNTs and CNTs display good anticoagulant property and negligible hemolytic effect to human red blood cells. With the enhanced mechanical property, great hemocompatibility, and previously demonstrated biocompatibility of both HNTs‐ and CNTs‐doped composite PLGA nanofibers, these composite nanofibers may be used as therapeutic artificial tissue/organ substitutes for tissue engineering applications. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

义眼台用羟基磷灰石的制备和性能

采用均相共沉淀法直接合成了高纯度羟基磷灰石粉体,通过改变反应物加入方式和反应时间调控粉体形貌和组成,分析了体系pH值对产物纯度的影响;以硅溶胶为粘结剂、尿素为造孔剂,室温下压制成型,高温烧结制备了孔隙度高、力学性能良好的多孔羟基磷灰石块体,考察了粉体粒径、造孔剂含量对孔隙度和抗压强度等性能的影响。结果表明,纳米粉有利于块体成型,随造孔剂含量增加,块体密度减小、孔隙度增加,当羟基磷灰石与尿素质量比为1.5:1时,孔隙度达69%,抗压强度达8 MPa,满足义眼台应用需求。     

Enhanced electromagnetic absorption properties of Fe-doped Sc2Si2O7 ceramics

Doping transition metal elements in a crystal causes distortion and defects in the lattice structure, which change the electronic structure and magnetic moment, thereby adjusting the electrical conductivity and electromagnetic properties of the material. Fe-doped Sc₂Si₂O₇ ceramics were synthesized using the sol-gel method for application to microwave absorption. The effect of Fe-doped content on the electromagnetic (EM) and microwave absorption properties was investigated in the Ku-band (12.4–18 GHz). As expected, the dielectric and magnetic properties improve substantially with increasing Fe content. Fe doping causes defects and impurity levels, which enhance polarization loss and conductance loss, respectively. Fe replaces Sc atoms in the ScO₆ octahedral structure, creating a difference in spin magnetic moments, which increases the magnetic moment. Moreover, the magnetic coupling of Fe and O atoms occurs at the Fermi level, which benefits magnetic loss. In particular, when the Fe content is 6%, the fabricated Fe-doped Sc₂Si₂O₇ ceramics show an absorption property with absorption peaks located at 14.5 GHz and a minimum reflection loss (RL_min) of ?12.8 dB. Therefore, Fe-doped Sc₂Si₂O₇ ceramics with anti-oxidation and good microwave absorption performance have a greater potential for application in high-temperature and water-vapor environments.     

Densification and electrical conductivity of Fe and Mn-doped Ce0.83Sm0.085Nd0.085O2-& by solid-liquid method

Fe and Mn-doped Ce_0.83Sm_0.085Nd_0.085O_2-& (SNDC) powders are successfully synthesized by the simple and efficient solid-liquid method. The crystallinity and morphologies of the powders were characterized by X-ray diffractometer, Raman spectrum, and scanning electron microscopy. The effect of doping on sintering behavior, grain interior, and grain boundary conductivity are studied. The doping of Fe can effectively reduce the sintering temperature from 1450^oC to 1250°C and keep the same density. Compared with SNDC, 1 mol% Fe-doped SNDC (Fe-SNDC) sintered at 1250°C shows a higher total conductivity of 2.13 × 10⁻² S·cm^-1 at 650°C. Also, it exhibits that doping of Fe can increase the conductivity of grain interior and grain boundary simultaneously. The present work shows that the Fe-SNDC synthesized by solid-liquid method can be used as a potential electrolyte for intermediate-temperature solid oxide fuel cells.     

Talc as a nucleating agent and reinforcing filler in poly(lactic acid) composites

The effect of talc on the crystallinity and mechanical properties of a series of poly(lactic acid) (PLA)/talc composites has been investigated. The composites were prepared by melt blending followed by compression molding. It was found that talc acted as a nucleating agent and increased the crystallinity of the PLA from 2% to 25%. There was significant improvement in Young's modulus of the composites with increasing talc addition and these results were found to fit the Halpin Tsai model. Thermo‐mechanical tests confirmed that the combination of increased crystallinity and storage modulus leads to improvement in the heat distortion properties. POLYM. ENG. SCI., 54:64–70, 2014. © 2013 Society of Plastics Engineers     

Structural and optical study of Fe3+-doped Al2O3 nanocrystals prepared by new sol gel precursors

Pure and Fe-doped Al₂O₃ nanoparticles (NPs) were synthesized with different iron doping percentage of 1, 3, and 5 mol% employing sol gel technique with AlCl₃, FeCl₃ as well as ethylene glycol (EG) and Polyvinylpyrrolidone (PVP) stabilizers as precursors. The XRD results indicated that the hexagonal structure of Fe/Al₂O₃ nanocomposite with alpha phase was formed by the substitution of Fe³⁺ ions in the alumina network. The sizes of the NPs obtained for the pure samples and doped samples at percentage dopant of 5% were 35 and 28 nm, respectively. The results of FTIR optical analysis showed the vibrational bond at the wavelength of 448 cm⁻¹, indicating the Al-O band in the sample. The UV-DRS analysis showed that the energy band gap for the pure NPs was 4 eV, but with increase in iron dopant up to 5%, it decreased to 3.42 eV. In addition, the results of photoluminescence (PL) analysis demonstrated that with increase in doping percentage, the PL intensity diminished. VSM magnetic analysis showed that with increase in iron dopant, the ferromagnetic state emerged in the NPs at saturation magnetism of 0.136 emu/g. Finally, photocatalytic experimental results demonstrated that 5% Fe-doped Al₂O₃ NPs effectively degrade MB approximately 53%.     

Development of a dual-functional Pt–Fe-HAP magnetic nanoparticles application for chemo-hyperthermia treatment of cancer

Lung cancer is a harmful form of cancer; chemotherapy is the main methodology for treating it, despite continuing problems such as severe side effects. For the reduction of side effects, hydroxyapatite (HAP) has been investigated as a drug carrier recently. Moreover, hyperthermia has been reported to be an effective cancer treatment modality. In order to develop an effective agent for lung cancer treatment, dual-functional nanoparticles made from HAP with iron and platinum ions incorporation (Pt–Fe-HAP) were developed for chemo-hyperthermia application.