Magnetic labeling of primary murine monocytes using very small superparamagnetic iron oxide nanoparticles

Due to their very small size,nanoparticles can interact with all cells in the central nervous system.One of the most promising nanoparticle subgroups are very small superparamagnetic iron oxide nanoparticles(VSOP)that are citrate coated for electrostatic stabilization.To determine their influence on murine blood-derived monocytes,which easily enter the injured central nervous system,we applied VSOP and carboxydextran-coated superparamagnetic iron oxide nanoparticles(Resovist).We assessed their impact on the viability,cytokine,and chemokine secretion,as well as iron uptake of murine blood-derived monocytes.We found that(1)the monocytes accumulated VSOP and Resovist,(2)this uptake seemed to be nanoparticle-and time-dependent,(3)the decrease of monocytes viability was treatment-related,(4)VSOP and Resovist incubation did not alter cytokine homeostasis,and(5)overall a 6-hour treatment with 0.75 mM VSOP-R1 was probably sufficient to effectively label monocytes for future experiments.Since homeostasis is not altered,it is safe to label blood-derived monocles with VSOP.VSOP labeled monocytes can be used to study injured central nervous system sites further,for example with drug-carrying VSOP.

Fluorescence detection of Europiumdoped very small superparamagnetic iron oxide nanoparticles in murine hippocampal slice cultures

In the late 1980s,superparamagnetic iron oxide nanoparticles（SPIO）moved into focus as contrast agents in magnetic resonance imaging（MRI）,due to their strong relaxivity and resulting higher resolution of images.At the time,no one anticipated their high potential in basic research or for medical diagnostic andtreatment. Since then, SPIO have been evaluated notonly as spe- cific markers for MRI, but also for cell labeling and tracking （Li et al., 2013）.

Preparation of Superparamagnetic Dextran-coated Iron Oxide Nanoparticles used as a Novel Gene Carrier into Human Bladder Cancer Cells'

Objective: Application of magnetic nanoparticles as gene carrier in gene therapy has developed quickly. This study was designed to investigate the preparation of superparamagnetic dextran-coated iron oxide nanoparticles (SDION) and the feasibility of SDION used as a novel gene carrier for plasmid DNA in vitro. Methods: SDION were prepared by chemical coprecipitation and separated by gel filtration on Sephacryl S-300HR, characterized by TEM, laser scattering system and Vibrating Sample Magnetometer Signal Processor. The green fluorescent protein (pGFP-C2) plasmid DNA was used as target gene. SDION-pGFP-C2 conjugate compounds were produced by means of oxidoreduction reaction. The connection ratio of SDION and pGFP-C2 DNA was analyzed and evaluated by agarose electrophoresis and the concentration of pGFP-C2 in supernatant was measured. Using liposome as control, the transfection efficiency of SDION and liposome was respectively evaluated under fluorescence microscope in vitro. Results: The diameter of SDION ranges from 3 nm to 8 nm, the effective diameter was 59.2 nm and the saturation magnetization was 0.23 emu/g. After SDION were reasonably oxidized, SDION could connect with pGFP-C2 to a high degree. The transfection efficiency of SDION as gene carrier was higher than that of liposome. Conclusion: The successes in connecting SDION with pGFP-C2 plasmid by means of oxidoreduction reaction and in transferring pGFP-C2 gene into human bladder cancer BIU-87 cells in vitro provided the experimental evidence for the feasibility of SDION used as a novel gene carrier.

Highly Efficient Labeling of Human Lung Cancer Cells Using Cationic Poly-L-lysine-Assisted Magnetic Iron Oxide Nanoparticles

Cell labeling with magnetic iron oxide nanoparticles(IONPs)is increasingly a routine approach in the cellbased cancer treatment.However,cell labeling with magnetic IONPs and their leading effects on the biological properties of human lung carcinoma cells remain scarcely reported.Therefore,in the present study the magnetic c-Fe2O3nanoparticles(MNPs)were firstly synthesized and surface-modified with cationic poly-L-lysine(PLL)to construct the PLL-MNPs,which were then used to magnetically label human A549 lung cancer cells.Cell viability and proliferation were evaluated with propidium iodide/fluorescein diacetate double staining and standard 3-(4,5-dimethylthiazol-2-diphenyl-tetrazolium)bromide assay,and the cytoskeleton was immunocytochemically stained.The cell cycle of the PLL-MNPlabeled A549 lung cancer cells was analyzed using flow cytometry.Apoptotic cells were fluorescently analyzed with nuclear-specific staining after the PLL-MNP labeling.The results showed that the constructed PLL-MNPs efficiently magnetically labeled A549 lung cancer cells and that,at low concentrations,labeling did not affect cellular viability,proliferation capability,cell cycle,and apoptosis.Furthermore,the cytoskeleton in the treated cells was detected intact in comparison with the untreated counterparts.However,the results also showed that at high concentration(400 lg m L-1),the PLL-MNPs would slightly impair cell viability,proliferation,cell cycle,and apoptosis and disrupt the cytoskeleton in the treated A549 lung cancer cells.Therefore,the present results indicated that the PLL-MNPs at adequate concentrations can be efficiently used for labeling A549 lung cancer cells and could be considered as a feasible approach for magnetic targeted anti-cancer drug/gene delivery,targeted diagnosis,and therapy in lung cancer treatment.

Use of PEI-coated Magnetic Iron Oxide Nanoparticles as Gene Vectors

Summary: To evaluate the feasibility of using polyethyleneimine (PEI) coated magnetic iron oxide nanoparticles (polyMAG-1000) as gene vectors. The surface characteristics of the nanoparticles were observed with scanning electron microscopy. The ability of the nanoparticles to combine with and protect DNA was investigated at different PH values after polyMAG-1000 and DNA were combined in different ratios. The nanoparticles were tested as gene vectors with in vitro transfection models. Under the scanning electron microscope the nanoparticles were about 100 nm in diameter. The nanoparticles could bind and condense DNA under acid, neutral and alkaline conditions, and they could transfer genes into cells and express green fluorescent proteins (GFP). The transfection efficiency was highest (51 %) when the ratio of nanoparticles to DNA was 1:1 (v:w). In that ratio, the difference in transfection efficiency was marked depending on whether a magnetic field was present or not: about 10 % when it was absent but 51 % when it was present. The magnetic iron oxide nanoparticles coated with PEI may potentially be used as gene vectors.

Bovine Serum Albumin-Conjugated Ferrimagnetic Iron Oxide Nanoparticles to Enhance the Biocompatibility and Magnetic Hyperthermia Performance

Magnetic hyperthermia is a fast emerging, non-invasive cancer treatment method which is used synergistically with the existing cancer therapeutics. We have attempted to address the current challenges in clinical magnetic hyperthermia-improved biocompatibility and enhanced heating characteristics, through a single combinatorial approach. Both superparamagnetic iron oxide nanoparticles(SPIONs) of size 10 nm and ferrimagnetic iron oxide nanoparticles(FIONs) of size 30 nm were synthesized by thermal decomposition method for comparison studies. Two different surface modifying agents, viz, Cetyl Trimethyl Ammonium Bromide and 3-Aminopropyltrimethoxysilane, were used to conjugate Bovine Serum Albumin(BSA) over the iron oxide nanoparticles via two different methods—surface charge adsorption and covalent amide bonding, respectively. The preliminary haemolysis and cell viability experiments show that BSA conjugation mitigates the haemolytic effect of the iron oxide nanoparticles on erythrocytes and is non-cytotoxic to the healthy Baby Hamster Kidney cells. It was observed from the results that due to better colloidal stability, the SAR value of the BSA-iron oxide nanoparticles is higher than the iron oxide nanoparticles without BSA, irrespective of the size of the iron oxide nanoparticles and method of conjugation. The BSA-FIONs seem to show improved biocompatibility, as the haemolytic index is less than 2 % and cell viability is up to 120 %, when normalized with the control. The SAR value of BSAFIONs is 2300 Wg^(-1) when compared to 1700 Wg^(-1) of FIONs without BSA conjugation. Thus, we report here that BSA conjugation over FIONs(with a high saturation magnetization of 87 emug^(-1)) provide a single combinatorial approach to improve the biocompatibility and enhance the SAR value for magnetic hyperthermia, thus addressing both the current challenges of the same.

Magnetic iron oxide nanoparticles carrying PTEN gene to reverse cisplatin-resistance of A549/CDDP cell lines

To evaluate the feasibility of using magnetic iron oxide nanoparticle as wild PTEN gene carrier for transfection in vitro to reverse cisplatin-resistance of A549/CDDP cells, A549/CDDP cells were transfected with the wild PTEN gene expression plasmid (pGFP-PTEN) by magnetic iron nanoparticle and lipo2000. The transfection efficiency was detected by fluorescence microscope and flow cytometer. The expression levels of PTEN mRNA and protein were detected by reverse transcription polymerase chain reaction (RT-PCR) and immunocytochemistry analysis. The effect of PTEN transfection on cell cycle enhances the sensitivity of A549/CDDP to cisplatin and nanoparticle-mediated transfection has a higher efficiency than that of the liposome-mediated group. The apoptosis level was up-regulated in PTEN transfection group. The magnetic iron oxide nanoparticle could be used as one of the ideal gene carriers for PTEN gene delivery in vitro. PTEN can be an effective target for reversing cisplatin-resistance in lung cancer.

Influence of magnetic iron oxide nanoparticles on red blood cells and Caco-2 cells

The interactions of two types of cells (red blood cells, Caco-2 cells) with magnetic iron oxide nanoparticles (non-grafted, citrate-grafted, dendrimer-grafted) of 11 nm in size have been investigated. We focused on two important physiological parameters of the cells, the intracellular pH and the intracellular Ca2+ content. The results show that the nanoparticles do not have a significant influence on the pH and Ca2+ content of Caco-2 cells. The Ca2+ content of red blood cells is also not affected but the intracellular pH is slightly reduced.

Structural, Magnetic and Heating Efficiency of Ball Milled γ-Fe2O3/Gd2O3 Nanocomposite for Magnetic Hyperthermia

The preparation of γ-Fe2O3/Gd2O3 nanocomposite for possible use in magnetic hyperthermia application was done by ball milling technique. The nanocomposite was characterized by X-ray diffraction (XRD) and vibrating sample magnetometer (VSM). The heating efficiency and the effect of milling time (5 h and 30 h) on the structural and magnetic properties of the nanocomposite were reported. XRD analysis confirms the formation of the nanocomposite, while magnetization measurements show that the milled sample present hysteresis with low coercivity and remanence. The specific absorption rate (SAR) under an alternating magnetic field is investigated as a function of the milling time. A mean heating efficiency of 68 W/g and 28.7 W/g are obtained for 5 h and 30 h milling times respectively at 332 kHz and 170 Oe. The results showed that the obtained nanocomposite for 5 h milling time is a promising candidate for magnetic hyperthermia due to his properties which show an interesting magnetic behavior and high specific absorption rate.

Magnetic Nano-Amorphous-Iron-Oxide-Based Drug Delivery System with Dual Therapeutic Mechanisms

Smart nanoparticles that respond to pathophysiological parameters,such as p H,GSH,and H2O2,have been developed with the huge and urgent demand for the high-efficient drug delivery systems(DDS)for cancer therapy.Herein,cubic poly(ethylene glycol)(PEG)-modified mesoporous amorphous iron oxide(AFe)nanoparticles(AFe-PEG)have been successfully prepared as p H-stimulated drug carriers,which can combine doxorubicin(DOX)with a high loading capacity of 948 mg/g,forming a novel multifunctional AFe-PEG/DOX nanoparticulate DDS.In an acidic microenvironment,the AFe-PEG/DOX nanoparticles will not only release DOX efficiently,but also release Fe ions to catalyze the transformation of H2O2 to·OH,acting as fenton reagents.In vitro experimental results proved that the AFe-PEG/DOX nanoparticles can achieve combination of chemotherapeutic(CTT)and chemodynamic therapeutic(CDT)effects on Hela tumor cells.Furthermore,the intrinsic magnetism of AFePEG/DOX makes its cellular internalization efficiency be improved under an external magnetic field.Therefore,this work develops a new and promising magnetically targeted delivery and dual CTT/CDT therapeutic nano-medicine platform based on amorphous iron oxide.

Doping engineering of iron oxide nanoparticles towards high performance and biocompatible T_(1)-weighted MRI contrast agents

Extremely small-sized iron oxide nanoparticles(IONPs) are of great interest in magnetic resonance imaging(MRI) due to their biosafety as an alternative to clinical gadolinium(Ⅲ) complexes-based contrast agents.Especially when the particle size is less than 10 nm,it has strong diffusion ability and deep penetration distance in tumor tissue.Substitution doping can significantly enhance the T_(1)contrast effect of nanoparticles by regulating the surface exposed atoms.However,the nucleation and growth processes of multi-component synthesis systems are complex and difficult to be accurately controlled,leading to great challenges in the synthesis of ultra-small-sized nanoparticles with different components and sizes.Here,extremely smallsized superparamagnetic gadolinium-doped iron oxide nanoparticles(GdIONPs,Gd_(x)Fe_(3-x)O_(4) NPs) with adjustable doping amount and controllable size in the range of 3.5-7.5 nm were synthesized by thermal decomposition.Then,as-synthesized GdIONPs were surface modified with a highly water-soluble and biocompatible carboxyl-polyethylene glycol-phosphoric acid ligand with high binding affinity.Gd_(0.65)Fe_(2.35)O_(4) NPs exhibited very high r_(1) relaxivity of 10.6 mmol^(-1)·L·s^(-1) in terms of all metal concentrations and 49.0 mmol^(-1)·L·s^(-1) in terms of gadolinium alone,respectively,3 and 14 times higher than clinical T_(1) contrast agents(Gd-DTPA).GdIONPs can continuously obtain high resolution images of blood vessels,and can be used as an efficient and multifunctional contrast agent for MR T_(1)imaging.This stable and efficient doping strategy provides an easy and effective method to individually optimize the magnetic properties of complex oxides and their relaxation effects for a variety of biomedical applications.

Effect of reaction and post-treatment conditions on physico-chemical properties of magnetic iron oxide nano-particles Author links open overlay panel

Poor stability and dispersibility,as well as aggregation are considered as major challenges in clinical application of iron oxide nanoparticles(IONPs).Several studies have shown that the synthesis parameters and post-synthesis treatments e.g.,drying methods,have the capability to improve the particles'characteristics.Herein,we investigate the combined effect of synthesis and post-treatment parameters on the particle size,stability and magnetism of IONPs.Magnetite(Fe_(3)O_(4))NPs were prepared via co-precipitation and post-treated using different methods,i.e.(i)freeze dried at-53℃,0.133 mbar for 48 h(liquid nitrogen frozen(LFD)and freezer frozen(FFD)),(ii)vacuum oven dried(VOD)at 60℃for 24 h,and(iii)kept wet colloidal(WET),dispersed in deionized water.The Fe_(3)O_(4)NPs’chemical functional groups,size,shape,crystallinity,stability,aggregation,porosity,and magnetic properties were further analysed using different characterisation techniques.Analytical results showed that,while the WET sample had the best stability and significantly less aggregation at different temperatures,amongst post-treated Fe_(3)O_(4)NPs,LFD sample exhibited the best stability(up to 37℃),dispersion and smallest polydispersity index.Furthermore,all dried NPs had superparamagnetic characteristics,while,LFD Fe_(3)O_(4)NPs had better magnetic properties and stability than other drying methods.

Immobilization of Penicillin G Acylase on Magnetic Nanoparticles Modified by Ionic Liquids

Functionalized ionic liquids containing ethyoxyl groups were synthesized and immobilized on magnetic silica nanoparticles （MSNP） prepared by two steps, i.e., Fe304 synthesis and silica shell growth on the surface. This magnetic nanoparticle supported ionic liquid （MNP-IL） were applied in the immobilization of penicillin G acylase （PGA）. The MSNPs and MNP-ILs were characterized by themeans of Fourier transform infrared spectroscopy （FTIR）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, and vibrating sample magnetometer （VSM）. The results showed that the average size of magnetic Fe304 nanoparticles and MSNPs were -10 and -90 nm, respectively. The saturation magnetizations of magnetic Fe304 nanoparticles and MNP-ILs were 63.7 and 26.9 A＇m2·kg^-1, respectively. The MNP-IL was successfully applied in the immobilization of PGA. The maximum amount of loaded enzyme-was about 209 mg·g^-1 （based on carder）, and the highest enzyme activity of immobilized PGA （based on ImPGA） was 261 U·g^-1. Both the amount of loaded enzyme and the activity of ImPGA are at the same leyel of or higher than that in previous reports. After 10 consecutive operat!ons, ImPGA still mainrained 62% of its initial activity, indicating the＇good recovery property of ImPGA activity. The ionic liquid modified magnetic particles integrate the magnetic properties of Fe304 and the structure-tunable properties of ionic liquids, and have extensive potential uses in protein immobilization and magnetic bioseparation. This work may open up a novel strategy to immobilize proteins by ionic liquids.

Spy chemistry enables stable protein immobilization on iron oxide nanoparticles with enhanced magnetic properties

Iron oxide nanoparticles(IONPs)modified with functional proteins hold great promise in the biomedical field.However,conventional protein modification strategies,such as adsorption and covalent coupling,are either unstable or nonspecific,or may result in the changes of protein structure and ultimately the loss of protein activity.Modification of active proteins on small-sized IONPs with a particle size of less than 30 nm is especially difficult due to their high surface energy.Herein,we developed a universal modifica-tion method based on Spy chemistry for rapid and stable protein immobilization on small-sized IONPs,which only requires the presence of active groups on the surface of nanoparticles that can couple with SpyCatcher.In short,the SpyCatcher peptides were first coated on the surface of IONPs by cross-linking with activated groups,and then the SpyTag peptide fused with a model protein(enhanced green fluo-rescent protein,EGFP)was engineered(SpyTag-EGFP)and directly coupled to SpyCatcher-modified IONPs by self-assembly,which is spontaneous and robust while avoiding the effect of chemical reactions on functional protein activity.The obtained EGFP-functionalized IONPs exhibited enhanced and stable green fluorescence and improved magnetic properties.In addition,the cell internalization efficiency of EGFP-functionalized IONPs was significantly increased as compared to unmodified IONPs,providing an ideal solution for efficient cell labeling and tracking.In conclusion,here we report a rapid and easy strategy for EGFP immobilization on IONPs based on Spy chemistry,which could be further adapted to other functional proteins in the future.SpyCatcher-modified IONPs and SpyTag-X(arbitrary functional fusion proteins)hold great potential to be applied as a versatile platform for protein immobilization on IONPs and enable its multifunctional application in the future.

Magnetite Nanoparticles Coated with Synthetic Polymer for Hyperthermia Application: Review

Hyperthermia treatment using appropriate magnetic materials in an alternating magnetic field to generate heat has been proposed as a low-invasive cancer treatment method. Magnetite iron oxide nanoparticles (Fe3O4) are expected to be an appropriate type of magnetic material for this purpose due to its biocompatibility. Several polymers are used to Fe3O4 MNPs to avoid or decrease agglomeration, and in most cases increase dispersion stability. In this review, we will give briefly how these coated magnetite nanoparticles (PMNPs) are synthesized in the first part. The main characterization techniques usually used to study the properties of these MNPs are prseneted in the second part. Finally, most recent results on the heating ability of polymeric coated magnetite nanoparticles (PMNPs) are given in the last part of this review.

磁性氧化铁纳米粒子应用于胰腺癌靶向诊疗的研究进展

胰腺癌预后极差,其早期诊断和治疗尤为关键。纳米技术已广泛应用于胰腺癌诊治,依靠纳米粒子的独特理化性质和其丰富的表面修饰手段可实现肿瘤部位的有效富集。磁性氧化铁纳米粒子(MIONPs)是胰腺癌诊治常用的纳米材料之一,具有良好的生物相容性。通过对其进行特殊的表面修饰,可应用于胰腺癌的靶向诊断和治疗。MIONPs可作为MRI的对比剂,通过修饰纳米粒子表面,可用于胰腺癌的靶向成像;还可将其改造为载药系统从而实现药物的靶向输送,提高治疗效果等。但是,MIONPs应用于胰腺癌诊疗仍然面临一些挑战,如纳米毒性和成本问题。随着技术发展,MIONPs有望在胰腺癌的个性化诊疗中发挥重要作用。

磁响应水凝胶在骨组织工程中的作用与优势

背景:磁响应水凝胶在骨组织工程中具有极大的优势,有利于微创、高效地促进成骨。目的:阐述磁响应水凝胶在骨组织工程领域的应用进展。方法:检索PubMed、Web of Science、万方和中国知网数据库检索相关文献,英文检索词为“Magnetic Hydrogels,Magnetic Nanoparticles,Superparamagnetic Nanoparticles,Fe3O4,SPIONs,Magnetic Fields,Bone Regeneration,Bone Repair,Bone Tissue Engineering”;中文检索词为“磁性水凝胶、磁性纳米粒子、超顺磁性氧化铁纳米粒、磁场、氧化铁纳米粒、骨再生、骨重建、骨修复、骨组织工程”,根据纳入与排除标准对所有文章进行初筛后,最终纳入60篇文章进行综述。结果与结论:①近年来由于磁性纳米粒子的出现,大量的磁响应支架材料被开发出来,其中,含有氧化铁纳米粒子和超顺磁性氧化铁纳米粒子的磁响应水凝胶力学性能突出、生物相容性良好,能够快速响应外部磁场,为种子细胞提供成骨所需的磁机械信号。②磁响应水凝胶可以作为载体精准调控生长因子的释放时机。③基于磁响应水凝胶的三维微环境培养平台下,磁响应水凝胶与细胞之间的界面磁力能够激活细胞表面敏感受体、增强细胞活性、促进新生骨质与宿主骨的整合。④可注射磁响应水凝胶能够应用于骨肿瘤的磁热疗以及生物成像领域。⑤目前,磁响应水凝胶有望模拟出天然骨组织中观察到的各向异性分层结构,然而关于磁响应水凝胶的研究大多集中于体外研究,与体内的局部微环境作用机制仍然不充分。⑥因此,目前基于磁性纳米粒子已经成功地应用于磁共振成像的示踪,未来有望在磁性纳米粒子的性能上优化,构建具有合适降解性能、机械性能和血管功能化的能够实时监测体内变化的磁响应水凝胶。

超顺磁性氧化铁纳米颗粒标记靶向癌胚抗原的CAR-T细胞及体外磁共振成像研究

目的采用超顺磁性氧化铁纳米颗粒(superparamagnetic iron oxide nanoparticles,SPIONs)标记靶向癌胚抗原(carcinoembryonic antigen,CEA)的嵌合抗原受体T细胞(chimeric antigen receptor T cells,CAR-T细胞),并进行体外磁共振成像研究,为监测CEA CAR-T细胞的体内回输治疗提供依据。方法将ferumoxytol、肝素钠和硫酸鱼精蛋白分别以高(ferumoxytol 100μg/mL,肝素钠4 IU/mL,硫酸鱼精蛋白120μg/mL)、中(ferumoxytol 50μg/mL,肝素钠2 IU/mL,硫酸鱼精蛋白60μg/mL)、低(ferumoxytol 25μg/mL,肝素钠1 IU/mL,硫酸鱼精蛋白30μg/mL)剂量混合形成SPIONs复合物FHP(ferumoxytol/heparin/protamine),然后与CEA CAR-T细胞共孵育进行细胞标记。CCK-8、EdU和流式细胞术检测FHP对细胞的生物相容性,普鲁士蓝染色检测细胞对FHP的摄入情况,电感耦合等离子体-质谱法(inductively coupled plasma-mass spectrometry,ICP-MS)定量检测细胞中Fe含量,流式细胞术检测FHP标记的CEA CAR-T细胞对肿瘤细胞的杀伤作用,磁共振成像(magnetic resonance imaging,MRI)扫描FHP标记的CEA CAR-T细胞。结果高、中、低剂量的FHP对CEA CAR-T细胞的活力没有明显影响,CCK-8实验显示细胞活性均在100%以上;EdU实验显示各组细胞DNA复制活性均在94.3%以上。普鲁士蓝染色显示CEA CAR-T细胞可摄取FHP,且随FHP浓度的增加,摄取量增大。ICP-MS进一步检测显示胞内Fe含量为(440.23±189.36)ng/mL。肿瘤细胞杀伤实验表明FHP标记的CEA CAR-T细胞的杀伤肿瘤细胞能力良好。MRI扫描显示随着FHP浓度的增高,FHP标记的CEA CAR-T细胞T2WI信号呈明显降低趋势(P<0.01)。结论SPIONs复合物FHP具有良好的生物相容性并能够有效标记CEA CAR-T细胞,可作为CEA CAR-T细胞的磁标记物,为临床提供一种可行的MRI示踪方法。

铁基纳米颗粒在磁共振成像中的研究进展

铁基纳米颗粒具有超顺磁性、低毒性、高磁化率等独特的物理、化学和高生物相容性的特点,是一类典型的磁共振成像(MRI)造影剂,包括磁性氧化铁纳米颗粒和超顺磁性氧化铁纳米颗粒两种。它能够与外加磁场产生局部磁矩,并引起局部磁场改变自旋方向,具有很好的对比度和信噪比,产生较高的MRI信号强度和对比度,能够提供清晰的图像。同时,铁基纳米颗粒具有较好的生物相容性和较低的细胞毒性,对人体安全性较高,特别是在MRI对肿瘤和炎症等疾病进行早期诊断和治疗时,在实现肿瘤协同精准治疗过程中发挥重要作用。随着铁基纳米颗粒合成技术的提高,医工多学科交叉融合可实现新型造影剂对靶点的精准定位和高分辨率成像,为疾病治疗和生物医学的发展做出巨大贡献。

基于转铁蛋白受体的磁共振成像示踪大鼠大脑铁代谢的实验研究

目的探讨基于转铁蛋白受体(TfR)在磁共振成像(MRI)示踪大鼠大脑铁代谢的应用效果,为临床开发监测阿尔茨海默病治疗效果的方法提供参考。方法选择健康成年SD大鼠12只,随机分为实验组和对照组,每组6只。实验组大鼠左侧大脑半球纹状体注入TfR慢病毒(TfR转染组),右侧大脑半球纹状体注入空载体EGFP慢病毒(EGFP转染组);对照组大鼠两侧大脑半球纹状体均注入等量生理盐水(正常组)。2周后经股静脉注入转铁蛋白-超小超顺磁性氧化铁纳米颗粒共轭物(Tf-USPIO)示踪剂15 mg/kg,分别于注射前及注射后1 d行MRI检查。MRI检查完毕后,予戊巴比妥钠麻醉大鼠,并通过断颈法将其处死,取大脑纹状体组织进行免疫荧光染色和普鲁士蓝染色。通过实时定量聚合酶链反应(PCR)检测大鼠纹状体脑组织TfR mRNA表达情况。结果实时定量PCR结果显示,TfR转染组脑组织TfR mRNA表达水平显著高于EGFP转染组和正常组(P<0.05)。免疫荧光染色和普鲁士蓝染色结果显示,TfR慢病毒成功转染大鼠脑组织,并成功模拟阿尔茨海默病大脑铁聚积的情况。在注射Tf-USPIO示踪剂前后,对照组大鼠MRI检查结果无明显变化;实验组大鼠左侧纹状体可见明显的信号改变,而右侧纹状体未见明显的信号改变。结论Tf-USPIO示踪剂可特异性结合脑组织的TfR,并可通过MRI显示,为临床开发监测阿尔茨海默病治疗效果的方法提供参考。