This paper reports the most prominent contributions in the field of biodegradable polymeric nanoparticles from poly (lactic-co-glycolic acid) (PLGA) used as a protein/drug delivery. We use a combination of Human Serum...This paper reports the most prominent contributions in the field of biodegradable polymeric nanoparticles from poly (lactic-co-glycolic acid) (PLGA) used as a protein/drug delivery. We use a combination of Human Serum Albumin (HSA)-superparamagnetic iron oxide nanoparticles (SPIONs) loaded PLGA nanoparticles. To obtain protein stabilization, the optimization of each step of synthesis nanoparticle is required. One of the most common problems in encapsulating protein to PLGA nanoparticles is the presence of several challenges as a problem of instability. We explained how the effect of the various sonication processing on the synthesis HSA-SPIONs loaded PLGA nanoparticles would be one of the crucial parameters for stability.展开更多
Limited research has suggested iron oxide nanoparticles (FeNP) have an inhibitory effect against several different genera of bacteria: Staphylococcus, Bacillus and Pseudomonas spp. In this study we looked at the effec...Limited research has suggested iron oxide nanoparticles (FeNP) have an inhibitory effect against several different genera of bacteria: Staphylococcus, Bacillus and Pseudomonas spp. In this study we looked at the effect of three different sets of Fe3O4 nanoparticles (FeNPs) on the development of Pseudomonas aeruginosa PAO1 biofilms. Two of the tested NPs were SPIONs (Superparamagnetic Iron Oxide Nanoparticles). Exposure of cells to the SPIONs at concentrations up to 200 μg/ml resulted in an increase in biofilm biomass by 16 h under static conditions and a corresponding increase in cell density in the bulk liquid. In contrast, these biofilms had decreased levels of extracellular DNA (eDNA). Fe(II) levels in the supernatants of biofilms formed in the presence of FeNPs exceeded 100 μM compared with 20 μM in control media without cells. Spent cell supernatants had little effect on Fe(II) levels. Cells also had an effect on the aggregation behavior of these nanoparticles. SPIONs incubated with cells exhibited a decrease in the number and size of FeNP aggregates visible using light microscopy. SPIONs resuspended in fresh media or spent culture supernatants formed large aggregates visible in the light microscope upon exposure to a supermagnet;and could be pelleted magnetically in microtitre plate wells. In contrast, SPION FeNPs incubated with cells were unaffected by exposure to the supermagnet and could not be pelleted. The results of this study indicate a need to reconsider the effects of FeNPs on bacterial growth and biofilm formation and the effect the bacterial cells may have on the use and recovery of SPIONs.展开更多
The Biodegradable nanoparticles from poly(lactic-co-glycolic acid) (PLGA) have been extensively investigated for sustained and targeted/localized delivery of different agents. Many parameters are required in the synth...The Biodegradable nanoparticles from poly(lactic-co-glycolic acid) (PLGA) have been extensively investigated for sustained and targeted/localized delivery of different agents. Many parameters are required in the synthesis of a biodegradable polymeric nanoparticle. We report the synthesis of human serum albumin (HSA)-superparamagnetic iron oxide nanoparticles (SPIONs) loaded PLGA nanoparticles. All nanoparticles were characterized using a TEM image, UV-Vis spectroscopy measurements, Zeta Potential, and PPMS for magnetizations. This study described and investigated the interesting phenomenon in the synthesis development of HSA-SPIONs loaded PLGA nanoparticles. The result showed that the stability of HSA-SPIONs loaded PLGA nanoparticles for potential applications such as in protein delivery.展开更多
In this study, 9 nm superparamagnetic iron oxide nanoparticles (SPION) were functionalized by polyamidoamine (PAMAM) dendrimer. Using tetracholoroauric acid (HAuCl4), magnetodendrimer (MD) samples were conjugated by g...In this study, 9 nm superparamagnetic iron oxide nanoparticles (SPION) were functionalized by polyamidoamine (PAMAM) dendrimer. Using tetracholoroauric acid (HAuCl4), magnetodendrimer (MD) samples were conjugated by gold nanoparticles (Au-NPs). Two different reducing agents, i.e. sodium borohydride and hydrazine sulfate, and pre-synthesized 10-nm Au-NP were used to evaluate the efficiency of conjugation method. The samples were characterized using X-ray diffractometry (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, UV-visible spectroscopy and fluorescence spectroscopy. The results confirmed that Au- NPs produced by sodium borohydrate and the pre-synthesized 10-nm Au-NPs were capped by MDs whereas the Au-NP prepared by hydrazine sulfate as a reducing agent was entrapped by MDs. Optical properties of the MDs were studied by laser-induced fluorescence spectroscopy (LIF) within a wide range of visible spectrum. Also, based on the thermal analysis, all synthesized nanostructures exhibited a temperature increase using 488 nm and 514 nm wavelengths of a tunable argon laser. The new iron oxide-dendrimer-Au NPs synthesized by sodium borohydrate (IDA- NaBH4) produced the highest temperature increase at 488 nm whereas the other nanostructures particularly pure Au-NPs produced more heating effect at 514 nm. These findings suggest the potential application of these nanocomposites in the field of bioimaging, targeted drug delivery and controlled hyperthermia.展开更多
Endothelin-1/endothelin A receptor(ET-1/ETAR)pathway plays an important role in the progression of liver fibrosis by activating hepatic stellate cells(HSCs)-a key cell type involved in the pathogenesis of liver fibros...Endothelin-1/endothelin A receptor(ET-1/ETAR)pathway plays an important role in the progression of liver fibrosis by activating hepatic stellate cells(HSCs)-a key cell type involved in the pathogenesis of liver fibrosis.Inactivating HSCs by blocking the ET-1/ETAR pathway using a selective ETAR antagonist(ERA)represents a promising therapeutic approach for liver fibrosis.Unfortunately,small-molecule ERAs possess limited clinical potential due to poor bioavailability,short half-life,and rapid renal clearance.To improve the clinical applicability,we conjugated ERA to superparamagnetic iron-oxide nanoparticles(SPIONs)and investigated the therapeutic efficacy of ERA and ERA-SPIONs in vitro and in vivo and analyzed liver uptake by in vivo and ex vivo magnetic resonance imaging(MRI),HSCs-specific localization,and ET-1/ETAR-pathway antagonism in vivo.In murine and human liver fibrosis/cirrhosis,we observed overexpression of ET-1 and ETAR that correlated with HSC activation,and HSC-specific localization of ETAR.ERA and successfully synthesized ERA-SPIONs demonstrated significant attenuation in TGFβ-induced HSC activation,ECM production,migration,and contractility.In an acute CCl4-induced liver fibrosis mouse model,ERA-SPIONs exhibited higher liver uptake,HSC-specific localization,and ET-1/ETAR pathway antagonism.This resulted in significantly reduced liver-to-body weight ratio,plasma ALT levels,andα-SMA and collagen-I expression,indicating attenuation of liver fibrosis.In conclusion,our study demonstrates that the delivery of ERA using SPIONs enhances the therapeutic efficacy of ERA in vivo.This approach holds promise as a theranostic strategy for the MRI-based diagnosis and treatment of liver fibrosis.展开更多
Superparamagnetic iron oxide nanoparticles(SPIONs),due to their controllable sizes,relatively long in vivo half-life and limited agglomeration,are ideal for biomedical applications such as magnetic labeling,hypertherm...Superparamagnetic iron oxide nanoparticles(SPIONs),due to their controllable sizes,relatively long in vivo half-life and limited agglomeration,are ideal for biomedical applications such as magnetic labeling,hyperthermia cancer treatment,targeted drug delivery and for magnetic resonance imaging(MRI)as contrast enhancement agents.In order to understand how SPIONs interact with cells and cellular membranes it would be of interest to characterize individual SPIONs at the nanoscale in physiologically relevant conditions without labeling them.We demonstrate that Magnetic Force Microscopy(MFM)can be used to image SPIONs in air as well as in liquid.The magnetic properties of bare and SiO2 coated SPIONs are compared using MFM.We report that surface modification using(3-mercaptopropyl)-trimethoxysilane significantly improves adsorption and distribution of SPIONs on gold surfaces.To obtain proof of principle that SPIONS can be imaged with MFM inside the cell we imaged SPIONs buried in thin polymer films(polystyrene(PS)and poly methyl-methacrylate(PMMA)).This opens the possibility of visualizing SPIONs inside the cell without any labeling or modifications and present MFM as a potential magnetic analogue for fluorescence microscopy.The results of these studies may have a valuable impact for characterization and further development of biomedical applications of SPIONs and other magnetic nanoparticles.展开更多
Nanoparticles have been widely explored for combined therapeutic and diagnostic applications. For example, lipid-based nanoparticles have been used to encapsulate multiple types of agents and achieve multi-functions. ...Nanoparticles have been widely explored for combined therapeutic and diagnostic applications. For example, lipid-based nanoparticles have been used to encapsulate multiple types of agents and achieve multi-functions. Herein, we enabled a co-delivery of mRNA molecules and superparamagnetic iron oxide nanoparticles （SPIONs） by using an amino-ester lipid-like nanomaterial. An orthogonal experimental design was used to identify the optimal formulation. The optimal formulation, MPA-Ab-8 LLNs, not only showed high encapsulation of both mRNA and SPIONs, but also increased the r2 relaxivity of SPIONs by more than 1.5-fold in vitro. MPA-Ab-8 LLNs effectively delivered mRNA and SPIONs into cells, and consequently induced high protein expression as well as strong MRI contrast. Consistent herewith, we observed both mRNA-mediated protein expression and an evident negative contrast enhancement of MRI signal in mice. In conclusion, amino-ester nanomaterials demonstrate great potential as delivery vehicles for theranostic applications.展开更多
目的综述超顺磁性氧化铁纳米粒(superparamagnetic iron oxide nanoparticles,SPION)作为磁共振成像造影剂的国内外研究进展。方法在Pubmed和Google资源上检索近30年来国内外相关资料,阐述磁共振成像造影剂原理和分类,介绍超顺磁性氧化...目的综述超顺磁性氧化铁纳米粒(superparamagnetic iron oxide nanoparticles,SPION)作为磁共振成像造影剂的国内外研究进展。方法在Pubmed和Google资源上检索近30年来国内外相关资料,阐述磁共振成像造影剂原理和分类,介绍超顺磁性氧化铁纳米粒的结构、特性及制备方法,对新一代超顺磁性氧化铁纳米粒造影剂在磁共振成像技术及其在生物医学中应用进行总结和评论。结果超顺磁性氧化铁纳米粒造影剂已成为磁共振成像中重要的临床诊断药物,在肝脏、淋巴系统和胰腺、中枢神经系统及肾脏疾病的诊断和治疗方面已取得系列成果。结论超顺磁性氧化铁纳米粒在医学基础研究和临床应用上具有广阔的应用前景,开发具有靶向性、高效、安全的超顺磁性氧化铁纳米粒造影是目前该领域研究主要方向之一。展开更多
We describe the results of 532 nm pulse laser-induced breakdown spectroscopy (LIBS) of two samples of magnetite nanoparticles (SPIONs) nanoferrofluid synthesized at room (S1) and elevated temperatures (S2) and at thre...We describe the results of 532 nm pulse laser-induced breakdown spectroscopy (LIBS) of two samples of magnetite nanoparticles (SPIONs) nanoferrofluid synthesized at room (S1) and elevated temperatures (S2) and at three different laser energy levels and pulse frequency. The size of magnetite nanoparticles, size distribution, magnetic crystalline phase and magnetization were analyzed and measured using transmission electron microscopy (TEM), X-ray diffraction spectroscopy (XRD) and vibrating sample magnetometry (VSM). The SPIONs showed a distribution between 4 - 22 nm with a peak about 12 nm and saturation magnetization of about 65 emu/g. The Saha-Boltzmann analysis of spectra for medium energy level (1050 mJ) yields plasma temperatures of (3881 ± 200) K and (26,047 ± 200) K for Fe I and OV as the lowest and highest temperatures respectively. A range of corresponding electron density (Ne-) of (0.47 - 6.80) × 1020, (0.58 - 8.30) × 1020 and (0.69 - 9.96) × 1020 cm-3?were determined at 860, 1050 and 1260 mJ respectively using the estimated CCD pictures. The results confirmed a higher elements ratio for S1 than S2 and the signal intensity indicated a non-linear behaviour as a function of pulse frequency with the maximum ratio value at 3 Hz. At higher frequency of 6 Hz no such turning point was observed. The highest and lowest temperatures corresponded to Fe I and OV respectively. The LIBS technique can be utilized to study, characterize and determine the elements ratio required in most applications involving the synthesizing process.展开更多
Superparamgnetic Fe_3O_4 and RE:Fe_3O_4(RE=Dy,Nd,La)nanoparticles with an average crystallite size in the range of 15–24 nm,were synthesized by co-precipitation method.The samples were characterized using X-ray diffr...Superparamgnetic Fe_3O_4 and RE:Fe_3O_4(RE=Dy,Nd,La)nanoparticles with an average crystallite size in the range of 15–24 nm,were synthesized by co-precipitation method.The samples were characterized using X-ray diffraction(XRD),scanning electron microscopy(SEM),vibrating sample magnetometer(VSM),UV–Vis spectroscopy,LCR bridge,and two-probe technique.X-ray diffraction patterns of all the investigated samples reveal the typical phase of magnetite structure,with a small contribution of orthoferrite(NdFeO_3)as a secondary phase in Nd:Fe_3O_4 sample.The saturation magnetization(M_s)of the samples has values in the range from 41.8 to 52.3 emu/g,and decreases with RE ion doping depending on the ionic radius.Negligible values of the coercivity H_c and remanenceM_r,indicate the superparamagnetic nature of the investigated samples.The calculated values of indirect optical band gap of Fe_3O_4 and RE:Fe_3O_4 nanoparticles are in the range of0.9–1.25 eV.The dielectric constant of the samples decreases,while their activation energy increases with the increasing of ionic radii of dopants.展开更多
文摘This paper reports the most prominent contributions in the field of biodegradable polymeric nanoparticles from poly (lactic-co-glycolic acid) (PLGA) used as a protein/drug delivery. We use a combination of Human Serum Albumin (HSA)-superparamagnetic iron oxide nanoparticles (SPIONs) loaded PLGA nanoparticles. To obtain protein stabilization, the optimization of each step of synthesis nanoparticle is required. One of the most common problems in encapsulating protein to PLGA nanoparticles is the presence of several challenges as a problem of instability. We explained how the effect of the various sonication processing on the synthesis HSA-SPIONs loaded PLGA nanoparticles would be one of the crucial parameters for stability.
文摘Limited research has suggested iron oxide nanoparticles (FeNP) have an inhibitory effect against several different genera of bacteria: Staphylococcus, Bacillus and Pseudomonas spp. In this study we looked at the effect of three different sets of Fe3O4 nanoparticles (FeNPs) on the development of Pseudomonas aeruginosa PAO1 biofilms. Two of the tested NPs were SPIONs (Superparamagnetic Iron Oxide Nanoparticles). Exposure of cells to the SPIONs at concentrations up to 200 μg/ml resulted in an increase in biofilm biomass by 16 h under static conditions and a corresponding increase in cell density in the bulk liquid. In contrast, these biofilms had decreased levels of extracellular DNA (eDNA). Fe(II) levels in the supernatants of biofilms formed in the presence of FeNPs exceeded 100 μM compared with 20 μM in control media without cells. Spent cell supernatants had little effect on Fe(II) levels. Cells also had an effect on the aggregation behavior of these nanoparticles. SPIONs incubated with cells exhibited a decrease in the number and size of FeNP aggregates visible using light microscopy. SPIONs resuspended in fresh media or spent culture supernatants formed large aggregates visible in the light microscope upon exposure to a supermagnet;and could be pelleted magnetically in microtitre plate wells. In contrast, SPION FeNPs incubated with cells were unaffected by exposure to the supermagnet and could not be pelleted. The results of this study indicate a need to reconsider the effects of FeNPs on bacterial growth and biofilm formation and the effect the bacterial cells may have on the use and recovery of SPIONs.
文摘The Biodegradable nanoparticles from poly(lactic-co-glycolic acid) (PLGA) have been extensively investigated for sustained and targeted/localized delivery of different agents. Many parameters are required in the synthesis of a biodegradable polymeric nanoparticle. We report the synthesis of human serum albumin (HSA)-superparamagnetic iron oxide nanoparticles (SPIONs) loaded PLGA nanoparticles. All nanoparticles were characterized using a TEM image, UV-Vis spectroscopy measurements, Zeta Potential, and PPMS for magnetizations. This study described and investigated the interesting phenomenon in the synthesis development of HSA-SPIONs loaded PLGA nanoparticles. The result showed that the stability of HSA-SPIONs loaded PLGA nanoparticles for potential applications such as in protein delivery.
文摘In this study, 9 nm superparamagnetic iron oxide nanoparticles (SPION) were functionalized by polyamidoamine (PAMAM) dendrimer. Using tetracholoroauric acid (HAuCl4), magnetodendrimer (MD) samples were conjugated by gold nanoparticles (Au-NPs). Two different reducing agents, i.e. sodium borohydride and hydrazine sulfate, and pre-synthesized 10-nm Au-NP were used to evaluate the efficiency of conjugation method. The samples were characterized using X-ray diffractometry (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, UV-visible spectroscopy and fluorescence spectroscopy. The results confirmed that Au- NPs produced by sodium borohydrate and the pre-synthesized 10-nm Au-NPs were capped by MDs whereas the Au-NP prepared by hydrazine sulfate as a reducing agent was entrapped by MDs. Optical properties of the MDs were studied by laser-induced fluorescence spectroscopy (LIF) within a wide range of visible spectrum. Also, based on the thermal analysis, all synthesized nanostructures exhibited a temperature increase using 488 nm and 514 nm wavelengths of a tunable argon laser. The new iron oxide-dendrimer-Au NPs synthesized by sodium borohydrate (IDA- NaBH4) produced the highest temperature increase at 488 nm whereas the other nanostructures particularly pure Au-NPs produced more heating effect at 514 nm. These findings suggest the potential application of these nanocomposites in the field of bioimaging, targeted drug delivery and controlled hyperthermia.
文摘Endothelin-1/endothelin A receptor(ET-1/ETAR)pathway plays an important role in the progression of liver fibrosis by activating hepatic stellate cells(HSCs)-a key cell type involved in the pathogenesis of liver fibrosis.Inactivating HSCs by blocking the ET-1/ETAR pathway using a selective ETAR antagonist(ERA)represents a promising therapeutic approach for liver fibrosis.Unfortunately,small-molecule ERAs possess limited clinical potential due to poor bioavailability,short half-life,and rapid renal clearance.To improve the clinical applicability,we conjugated ERA to superparamagnetic iron-oxide nanoparticles(SPIONs)and investigated the therapeutic efficacy of ERA and ERA-SPIONs in vitro and in vivo and analyzed liver uptake by in vivo and ex vivo magnetic resonance imaging(MRI),HSCs-specific localization,and ET-1/ETAR-pathway antagonism in vivo.In murine and human liver fibrosis/cirrhosis,we observed overexpression of ET-1 and ETAR that correlated with HSC activation,and HSC-specific localization of ETAR.ERA and successfully synthesized ERA-SPIONs demonstrated significant attenuation in TGFβ-induced HSC activation,ECM production,migration,and contractility.In an acute CCl4-induced liver fibrosis mouse model,ERA-SPIONs exhibited higher liver uptake,HSC-specific localization,and ET-1/ETAR pathway antagonism.This resulted in significantly reduced liver-to-body weight ratio,plasma ALT levels,andα-SMA and collagen-I expression,indicating attenuation of liver fibrosis.In conclusion,our study demonstrates that the delivery of ERA using SPIONs enhances the therapeutic efficacy of ERA in vivo.This approach holds promise as a theranostic strategy for the MRI-based diagnosis and treatment of liver fibrosis.
基金funded by Natural Science and Engineering Council of Canada(NSERC).
文摘Superparamagnetic iron oxide nanoparticles(SPIONs),due to their controllable sizes,relatively long in vivo half-life and limited agglomeration,are ideal for biomedical applications such as magnetic labeling,hyperthermia cancer treatment,targeted drug delivery and for magnetic resonance imaging(MRI)as contrast enhancement agents.In order to understand how SPIONs interact with cells and cellular membranes it would be of interest to characterize individual SPIONs at the nanoscale in physiologically relevant conditions without labeling them.We demonstrate that Magnetic Force Microscopy(MFM)can be used to image SPIONs in air as well as in liquid.The magnetic properties of bare and SiO2 coated SPIONs are compared using MFM.We report that surface modification using(3-mercaptopropyl)-trimethoxysilane significantly improves adsorption and distribution of SPIONs on gold surfaces.To obtain proof of principle that SPIONS can be imaged with MFM inside the cell we imaged SPIONs buried in thin polymer films(polystyrene(PS)and poly methyl-methacrylate(PMMA)).This opens the possibility of visualizing SPIONs inside the cell without any labeling or modifications and present MFM as a potential magnetic analogue for fluorescence microscopy.The results of these studies may have a valuable impact for characterization and further development of biomedical applications of SPIONs and other magnetic nanoparticles.
文摘Nanoparticles have been widely explored for combined therapeutic and diagnostic applications. For example, lipid-based nanoparticles have been used to encapsulate multiple types of agents and achieve multi-functions. Herein, we enabled a co-delivery of mRNA molecules and superparamagnetic iron oxide nanoparticles （SPIONs） by using an amino-ester lipid-like nanomaterial. An orthogonal experimental design was used to identify the optimal formulation. The optimal formulation, MPA-Ab-8 LLNs, not only showed high encapsulation of both mRNA and SPIONs, but also increased the r2 relaxivity of SPIONs by more than 1.5-fold in vitro. MPA-Ab-8 LLNs effectively delivered mRNA and SPIONs into cells, and consequently induced high protein expression as well as strong MRI contrast. Consistent herewith, we observed both mRNA-mediated protein expression and an evident negative contrast enhancement of MRI signal in mice. In conclusion, amino-ester nanomaterials demonstrate great potential as delivery vehicles for theranostic applications.
文摘目的综述超顺磁性氧化铁纳米粒(superparamagnetic iron oxide nanoparticles,SPION)作为磁共振成像造影剂的国内外研究进展。方法在Pubmed和Google资源上检索近30年来国内外相关资料,阐述磁共振成像造影剂原理和分类,介绍超顺磁性氧化铁纳米粒的结构、特性及制备方法,对新一代超顺磁性氧化铁纳米粒造影剂在磁共振成像技术及其在生物医学中应用进行总结和评论。结果超顺磁性氧化铁纳米粒造影剂已成为磁共振成像中重要的临床诊断药物,在肝脏、淋巴系统和胰腺、中枢神经系统及肾脏疾病的诊断和治疗方面已取得系列成果。结论超顺磁性氧化铁纳米粒在医学基础研究和临床应用上具有广阔的应用前景,开发具有靶向性、高效、安全的超顺磁性氧化铁纳米粒造影是目前该领域研究主要方向之一。
文摘We describe the results of 532 nm pulse laser-induced breakdown spectroscopy (LIBS) of two samples of magnetite nanoparticles (SPIONs) nanoferrofluid synthesized at room (S1) and elevated temperatures (S2) and at three different laser energy levels and pulse frequency. The size of magnetite nanoparticles, size distribution, magnetic crystalline phase and magnetization were analyzed and measured using transmission electron microscopy (TEM), X-ray diffraction spectroscopy (XRD) and vibrating sample magnetometry (VSM). The SPIONs showed a distribution between 4 - 22 nm with a peak about 12 nm and saturation magnetization of about 65 emu/g. The Saha-Boltzmann analysis of spectra for medium energy level (1050 mJ) yields plasma temperatures of (3881 ± 200) K and (26,047 ± 200) K for Fe I and OV as the lowest and highest temperatures respectively. A range of corresponding electron density (Ne-) of (0.47 - 6.80) × 1020, (0.58 - 8.30) × 1020 and (0.69 - 9.96) × 1020 cm-3?were determined at 860, 1050 and 1260 mJ respectively using the estimated CCD pictures. The results confirmed a higher elements ratio for S1 than S2 and the signal intensity indicated a non-linear behaviour as a function of pulse frequency with the maximum ratio value at 3 Hz. At higher frequency of 6 Hz no such turning point was observed. The highest and lowest temperatures corresponded to Fe I and OV respectively. The LIBS technique can be utilized to study, characterize and determine the elements ratio required in most applications involving the synthesizing process.
基金the Deanship of Scientific Research at King Khalid University for funding this work through General Research Project under grant number G.R.P-310-38
文摘Superparamgnetic Fe_3O_4 and RE:Fe_3O_4(RE=Dy,Nd,La)nanoparticles with an average crystallite size in the range of 15–24 nm,were synthesized by co-precipitation method.The samples were characterized using X-ray diffraction(XRD),scanning electron microscopy(SEM),vibrating sample magnetometer(VSM),UV–Vis spectroscopy,LCR bridge,and two-probe technique.X-ray diffraction patterns of all the investigated samples reveal the typical phase of magnetite structure,with a small contribution of orthoferrite(NdFeO_3)as a secondary phase in Nd:Fe_3O_4 sample.The saturation magnetization(M_s)of the samples has values in the range from 41.8 to 52.3 emu/g,and decreases with RE ion doping depending on the ionic radius.Negligible values of the coercivity H_c and remanenceM_r,indicate the superparamagnetic nature of the investigated samples.The calculated values of indirect optical band gap of Fe_3O_4 and RE:Fe_3O_4 nanoparticles are in the range of0.9–1.25 eV.The dielectric constant of the samples decreases,while their activation energy increases with the increasing of ionic radii of dopants.
