壳聚糖修饰Fe3O4纳米颗粒的制备及其磁共振造影性能

采用碳二亚胺法将壳聚糖(CS)分子链上的—NH_2和羧基化Fe_3O_4(Fe_3O_4-COOH)纳米粒子表面的—COOH共价耦联,制备壳聚糖修饰的Fe_3O_4(CS-Fe_3O_4)纳米颗粒。通过纳米粒度仪、透射电子显微镜(TEM)、傅里叶变换红外(FT-IR)光谱仪、X-射线衍射(XRD)分析仪、低温综合物性测试系统分别对CS-Fe_3O_4纳米颗粒的粒径分布、表面形态、化学结构、晶体结构及磁学性质进行测试,并研究其作为T2造影剂的体外磁共振造影能力。结果表明,制备的CS-Fe_3O_4纳米颗粒形态圆整、大小均一,水合动力学平均粒径为109.2 nm,具有良好的分散稳定性及超顺磁性;体外磁共振显像实验表明该纳米粒子具有负性显像能力,并且其负性显像能力随Fe_3O_4浓度增加而增强。因此,CS-Fe_3O_4纳米颗粒有望成为一种新型的磁共振T2造影剂。     

Fe3O4@SiO2@IPDI-HEA改性水性有机硅聚氨酯光固化膜的性能

以Fe_3O_4纳米粒子为核、丙烯酸酯为壳,通过溶剂热法制备了Fe_3O_4@SiO_2@IPDI-HEA纳米粒子。通过IR、TEM和XRD对其结构进行了表征,通过光差热扫描(photo-DSC)和TGA考察了该纳米粒子对水性有机硅聚氨酯光固化体系性能的影响。结果表明:Fe_3O_4@SiO_2@IPDI-HEA粒子的加入,对体系的光聚合性能没有明显影响,但可明显提高固化膜的耐热性和拉伸强度,当Fe_3O_4@SiO_2@IPDI-HEA的质量分数为1.5%时,固化膜的初始分解温度(T5%)增加了21.9℃,拉伸强度增加了6.9MPa。并且,Fe_3O_4@SiO_2@IPDI-HEA可以赋予光固化膜一定的电磁性能,当频率在0～(1×10~7) Hz内时,其介电常数均在4以上。     

氨基化Fe_3O_4纳米粒子的制备及对胃癌细胞的毒性评价

采用共沉淀法制备了四氧化三铁纳米粒子(Fe_3O_4),并在Fe_3O_4纳米粒子表面修饰上了氨基。透射电子显微镜(TEM)和傅里叶变换红外光谱(FTIR)显示,纳米粒子分散性良好,粒径约为10 nm,氨基成功修饰在了纳米粒子的表面。以胃癌SGC-7901为目的细胞,依据RGR值考察了Fe_3O_4-NH_2纳米粒子的细胞毒性等级,结果显示,在一定浓度范围内,细胞死亡率与Fe_3O_4-NH_2纳米粒子的浓度成正相关,低于51.2μg/m L时,Fe_3O_4-NH_2纳米粒子的细胞毒性相对较小,Fe_3O_4-NH_2纳米颗粒具有较好的生物相容性。     

聚丙烯腈/氧化铁纳米粒子复合纳米纤维的制备及表征

利用静电纺丝技术制备了一种聚丙烯腈(PAN)/氧化铁(Fe_2O_3)纳米粒子复合纳米纤维。不同分子量的PAN得到不同直径的纤维薄;将PAN的N,N-二甲基甲酰胺溶液(DMF)与纳米Fe_2O_3混合得到PAN/Fe_2O_3溶液,然后利用静电纺丝技术制备PAN/Fe_2O_3纳米粒子复合纳米纤维;将静电纺丝制备的PAN纳米纤维膜与氯化铁(FeCl_3)溶液在不同p H条件下水热合成PAN/Fe_2O_3纳米粒子复合纳米纤维。采用扫描电子显微镜(SEM)、热重分析仪(TGA)对纳米纤维膜进行表征。结果表明:静电纺丝制备的PAN纳米纤维在水热条件下可以一定程度上克服Fe_2O_3纳米粒子易团聚问题。     

磁性Fe3O4纳米粒子的制备

磁性四氧化三铁(Fe_3O_4)纳米粒子以其比表面积大、低毒性和良好的生物相容性等物理化学性质而得到广泛关注。采用共沉淀法制备磁性四氧化三铁(Fe_3O_4)纳米粒子,并通过单因素实验优化制备工艺。结果表明,制备Fe_3O_4纳米粒子的优化工艺参数为:Fe~(2+)与Fe~(3+)浓度比为1.00∶1.50、铁盐浓度为0.30 mol·L~(-1)、反应温度为60℃、 NaOH溶液的浓度为0.25 mol·L~(-1)。该条件下,Fe_3O_4纳米粒子形貌为球形,平均粒径为65.15 nm,饱和磁强度为63.5 emu·g~(-1)。     

磁性载银纳米粒子的制备及催化降解对硝基苯酚的应用

首先以水热法合成了高度分散性的磁性纳米粒子Fe_3O_4,然后在Stber条件下以正硅酸乙酯为硅源,制备了具有核-壳结构的Fe_3O_4@SiO_2。以Fe_3O_4@SiO_2作为磁性载体,利用乙二胺的温和还原性,在AgNO_3的乙醇溶液中,成功地将Ag纳米粒子沉积在Fe_3O_4@SiO_2表面,得到了Fe_3O_4@SiO_2@Ag磁性纳米粒子。分别用X射线衍射仪(XRD)、傅里叶红外光谱仪(FT-IR)、电子扫描电镜(SEM)和电子透射电镜(TEM)对产品进行表征,并将磁性纳米粒子作为固体催化剂,用于催化硼氢化钠还原4-硝基酚的反应中。结果表明,该催化剂效果良好,方便从混合物中分离并重复使用,可重复利用6次以上。     

苝酰胺功能化磁性纳米材料的合成及其光/电性质

为了制备磁性荧光以及光电化学性能良好的多功能纳米粒子,采用微相乳液法,用二氧化硅(SiO_2)包裹Fe_3O_4磁性纳米粒子的同时,将苝酰胺与SiO_2表面的羟基反应,生成共价键连接的Fe_3O_4@SiO_2-(1a)和Fe_3O_4@SiO_2-(2a)纳米粒子,用红外光谱、XRD、SEM、UV-Vis吸收光谱、荧光光谱及ECL进行表征。结果表明,与化合物1a、2a相比,复合物Fe_3O_4@SiO_2-(1a/2a)的电子吸收和荧光光谱峰型相同,峰位置略有移动。在一定浓度范围内,Fe_3O_4@SiO_2-(2a)纳米粒子的ECL强度随浓度增大而降低,且其在50~100 s的区间内基本稳定。     

苝酰胺功能化磁性纳米材料的合成及其光/电性质

为了制备磁性荧光以及光电化学性能良好的多功能纳米粒子,采用微相乳液法,用二氧化硅(SiO_2)包裹Fe_3O_4磁性纳米粒子的同时,将苝酰胺与SiO_2表面的羟基反应,生成共价键连接的Fe_3O_4@SiO_2-(1a)和Fe_3O_4@SiO_2-(2a)纳米粒子,用红外光谱、XRD、SEM、UV-Vis吸收光谱、荧光光谱及ECL进行表征。结果表明,与化合物1a、2a相比,复合物Fe_3O_4@SiO_2-(1a/2a)的电子吸收和荧光光谱峰型相同,峰位置略有移动。在一定浓度范围内,Fe_3O_4@SiO_2-(2a)纳米粒子的ECL强度随浓度增大而降低,且其在50¹00 s的区间内基本稳定。     

磁性Fe3O4纳米颗粒负载糖苷生物碱微球的制备

以硫酸亚铁铵[(NH_4)_2Fe(SO_4)_2·6H_2O]为铁源,氢氧化钠为沉淀剂,过硫酸铵[(NH_4)_2S_2O_8]为氧化剂,采用沉淀法制备了Fe_3O_4磁性纳米颗粒;采用石油醚萃取的方法从马铃薯皮中提取了糖苷生物碱;通过超声混合并研磨的方法将其与糖苷生物碱(SGAs)复合,制备了Fe_3O_4/SGAs复合材料,并对样品进行了X-射线粉末衍射(XRD)、红外吸收光谱(FT-IR)、透射电子显微镜(TEM)等表征。结果表明,所制备的Fe_3O_4纳米粒子具有尖晶石结构且Fe_3O_4与糖苷生物碱发生了有效复合。     

一种Au@Fe_3O_4纳米复合粒子的快速合成方法

团簇状的Au@Fe_3O_4纳米复合粒子采用两步法进行合成。首先通过共沉淀法合成柠檬酸修饰的Fe_3O_4纳米粒子;其次以柠檬酸纳为温和的还原剂将HAuCl_4快速还原为Au纳米粒子而沉积在Fe_3O_4的表面。并考察了HAuCl_4及柠檬酸修饰的Fe_3O_4纳米粒子用量对合成过程的影响。采用紫外-可见分光光度计(UV-vis)、动态光散射仪(DLS)及透射扫描电镜(TEM)等测试手段对所制备的纳米粒子进行了表征。结果表明:当V(1%HAuCl_4)=1.8 m L,m(柠檬酸修饰的Fe_3O_4)=12.5 mg时,Au@Fe_3O_4纳米复合粒子的中心Au纳米粒子的粒径大小为20~50 nm左右而周围包覆的Fe_3O_4纳米粒子的大小为10 nm左右,且其在水中能够稳定的存在3个月而粒径大小无明显的变化。     

Monodisperse magnetic nanoparticles for theranostic applications

Effective medical care requires the concurrent monitoring of medical treatment. The combination of imaging and therapeutics allows a large degree of control over the treatment efficacy and is now commonly referred to as "theranostics". Magnetic nanoparticles (NPs) provide a unique nanoplatform for theranostic applications because of their biocompatibility, their responses to the external magnetic field, and their sizes which are comparable to that of functional biomolecules. Recent studies of magnetic NPs for both imaging and therapeutic applications have led to greater control over size, surface functionalization, magnetic properties, and specific binding capabilities of the NPs. The combination of the deep tissue penetration of the magnetic field and the ability of magnetic NPs to enhance magnetic resonance imaging sensitivity and magnetic heating efficiency makes magnetic NPs promising candidates for successful future theranostics. In this Account, we review recent advances in the synthesis of magnetic NPs for biomedical applications such as magnetic resonance imaging (MRI) and magnetic fluid hyperthermia (MFH). Our focus is on iron oxide (Fe(3)O(4)) NPs, gold-iron oxide (Au-Fe(3)O(4)) NPs, metallic iron (Fe) NPs, and Fe-based alloy NPs, such as iron-cobalt (FeCo) and iron-platinum (FePt) NPs. Because of the ease of fabrication and their approved clinical usage, Fe(3)O(4) NPs with controlled sizes and surface chemistry have been studied extensively for MRI and MFH applications. Porous hollow Fe(3)O(4) NPs are expected to have similar magnetic, chemical, and biological properties as the solid Fe(3)O(4) NPs, and their structures offer the additional opportunity to store and release drugs at a target. The Au-Fe(3)O(4) NPs combine both magnetically active Fe(3)O(4) and optically active Au within one nanostructure and are a promising NP platform for multimodal imaging and therapeutics. Metallic Fe and FeCo NPs offer the opportunity for probes with even higher magnetizations. However, metallic NPs are normally very reactive and are subject to fast oxidation in biological solutions. Once they are coated with a layer of polycrystalline Fe(3)O(4) or a graphitic shell, these metallic NPs are more stable and provide better contrast for MRI and more effective heating for MFH. FePt NPs are chemically more stable than Fe and FeCo NPs and have shown great potential as contrast agents for both MRI and X-ray computed tomography (CT) and as robust probes for controlled heating in MFH.     

Core-shell Fe3O4@SiO2 nanoparticles synthesized with well-dispersed hydrophilic Fe3O4 seeds

Silica coated magnetite (Fe3O4@SiO2) core-shell nanoparticles (NPs) with controlled silica shell thicknesses were prepared by a modified St?ber method using 20 nm hydrophilic Fe3O4 NPs as seeds. The core-shell NPs were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), selected area electron diffraction (SAED), and UV-Vis adsorption spectra (UV-Vis). The results imply that NPs consist of a crystalline magnetite core and an amorphous silica shell. The silica shell thickness can be controlled from 12.5 nm to 45 nm by varying the experimental parameters. The reaction time, the ratio of TEOS/Fe3O4, and the concentration of hydrophilic Fe3O4 seeds were found to be very influential in the control of silica shell thickness. These well-dispersed core-shell Fe3O4@SiO2 NPs show superparamagnetic properties at room temperature.     

A three-dimensional, magnetic and electroactive nanoprobe for amperometric determination of tumor biomarkers

A novel electrochemical immunosensor for tumor biomarker detection based on three-dimensional, magnetic and electroactive nanoprobes was developed in this study. To fabricate the nanoprobes, negatively charged Fe(3)O(4) nanoparticles (Fe(3)O(4) NPs) and gold nanoparticles (Au NPs) were first loaded on the surface of multiple wall carbon nanotubes (MCNTs) which were functioned with redox-active hemin and cationic polyelectrolyte poly(dimethyldiallylammonium chloride) (PDDA). Using alpha fetoprotein (AFP) as a model analyte, AFP antibody (anti-AFP) was absorbed on the surface of Au NPs, bovine serum albumin (BSA) was then used to block sites against non-specific binding, and finally formed anti-AFP/Au NPs/Fe(3)O(4)/hemin/MCNTs named anti-AFP nanoprobes. When the target antigen AFP was present, it interacted with anti-AFP and formed an antigen-antibody complex on the nanoprobe interface. This resulted in a decreased electrochemical signal of hemin for quantitative determination of AFP when immobilized onto the screen-printed working electrode (SPCE). The results showed that the nanoprobe-based electrochemical immunosensor was sensitive to AFP detection at a concentration of 0.1 to 200 ng·mL(-1) with a detection limit of 0.04 ng·mL(-1), it also demonstrated good selectivity against other interferential substances. The electroactive nanoprobes can be massively prepared, easily immobilized on the SPCE for target detection and rapidly renewed with a magnet. The proposed immunosensor is fast, simple, sensitive, stable, magnet-controlled, nontoxic, label-free and reproducible.     

污泥厌氧资源化利用积累SCFA的新策略及作用机制

为了探究磁铁矿对剩余污泥厌氧发酵生产短链脂肪酸(SCFA)的影响,以剩余污泥为研究对象,建立序批式厌氧反应器,通过比较pH,溶解性化学需氧量(SCOD),SCFA及乙酸钠的变化探究了磁铁矿纳米材料(Fe3O4NPs)对污泥厌氧发酵的影响。实验结果表明Fe3O4纳米材料的存在能够增加SCOD和SCFA含量,当Fe3O4NPs由0 mg/L增加至300 mg/L时,SCOD和SCFA的最大质量浓度分别由3256、1524 mg/L增加至4015、3460 mg/L。进一步研究发现适量Fe3O4NPs投加有助于乙酸钠的降解,而过量Fe3O4NPs的投加却抑制乙酸钠的降解。适量Fe3O4NPs的投加为厌氧微生物提供了微量元素,强化了微生物的活性。揭示Fe3O4NPs对污泥厌氧消化产酸的影响行为,为推动污泥厌氧消化技术进步提供理论依据和技术支撑。     

快速配体交换法制备水溶性磁性Fe3O4纳米粒子

为了获得水溶性Fe_3O_4纳米粒子,以聚乙二醇(PEG)磷酸酯为亲水性配体,在甲苯/四氢呋喃/水三元混合溶剂体系下通过快速配体交换法将油酸包覆的油溶性磁性Fe_3O_4纳米粒子转变成聚乙二醇磷酸酯包覆的水溶性Fe_3O_4纳米粒子。考察了四氢呋喃等溶剂在实现快速配体交换中所起到的作用。利用透射电子显微镜(TEM)、动态光散射(DLS)、X射线粉末衍射仪(XRD)、傅立叶红外光谱仪(FTIR)、振动样品磁强计(VSM)对磁性Fe_3O_4纳米粒子进行了分析表征。结果表明:四氢呋喃可以促进PEG磷酸酯与Fe_3O_4纳米粒子表面的有效接触并使得油酸分子从纳米粒子表面快速地脱附下来,此外,还消除了配体交换过程中出现的乳化效应。四氢呋喃的应用实现了快速配体交换法制备水溶性PEG磷酸酯包覆的磁性纳米粒子。     

磁性N-羧甲基壳聚糖造影剂的制备及性能

采用简单经济(与传统微乳法、热分解法等比较)的方法制备出一种磁性N-羧甲基壳聚糖造影剂。首先对壳聚糖的氨基进行羧甲基化制备N-羧甲基壳聚糖,然后在其链上采用原位生成Fe3O4纳米粒子的方法制备出磁性N-羧甲基壳聚糖,并对其进行了表征及性能的测试。热重分析结果表明,Fe3O4的生成量与N-羧甲基壳聚糖中羧甲基的含量有关,其生成量随着羧甲基含量的增加而增加,但当羧甲基的含量增加到一定程度时,Fe3O4的生成量达到某一峰值。透射电镜结果表明,生成的Fe3O4纳米粒子的粒径约为5～10 nm。磁共振成像结果显示,该磁性N-羧甲基壳聚糖的横向弛豫率为82.82 mmol/(L.s),高于超顺磁性氧化铁作为磁共振成像造影剂时R2需大于62 mmol/(L.s)的最低标准,可作为潜在的磁共振成像阴性造影剂。     

磁性Fe3O4@SiO2颗粒结构对其吸附DNA的影响

采用共沉淀法和水热法制备了不同结构的超顺磁性Fe3O4@SiO2纳米颗粒,对其进行表征,研究了其吸附DNA的性能及磁分离性能. 结果表明,20?750 nm范围内粒径较大的颗粒与DNA结合时可提供更多单位平面结合位点,使结合的稳定性和结合几率增加,DNA结合量提高. 不同核?壳结构的Fe3O4@SiO2纳米颗粒的磁分离响应时间不同,内核大小相近时,壳层厚度增加会导致颗粒在磁场中受到的磁力与阻力的比值减小,磁响应时间增加,DNA回收率降低. 粒径约为200 nm的Fe3O4@SiO2纳米颗粒用于纯化全血中DNA最好,提取率为95.2%,磁响应时间为10 s.     

Highly selective fluorescent chemosensor for Zn2+ derived from inorganic-organic hybrid magnetic core/shell Fe3O4@SiO2 nanoparticles

ABSTRACT: Magnetic nanoparticles with attractive optical properties have been proposed for applications in such areas as separation and magnetic resonance imaging. In this paper, a simple and novel fluorescent sensor of Zn2+ was designed with 3,5-di-tert-butyl-2-hydroxybenzaldehyde [DTH] covalently grafted onto the surface of magnetic core/shell Fe3O4@SiO2 nanoparticles [NPs] (DTH-Fe3O4@SiO2 NPs) using the silanol hydrolysis approach. The DTH-Fe3O4@SiO2 inorganic-organic hybrid material was characterized by transmission electron microscopy, dynamic light scattering, X-ray power diffraction, diffuse reflectance infrared Fourier transform, UV-visible absorption and emission spectrometry. The compound DTH exhibited fluorescence response towards Zn2+ and Mg2+ ions, but the DTH-Fe3O4@SiO2 NPs only effectively recognized Zn2+ ion by significant fluorescent enhancement in the presence of various ions, which is due to the restriction of the N-C rotation of DTH-Fe3O4@SiO2 NPs and the formation of the rigid plane with conjugation when the DTH-Fe3O4@SiO2 is coordinated with Zn2+. Moreover, this DTH-Fe3O4@SiO2 fluorescent chemosensor also displayed superparamagnetic properties, and thus, it can be recycled by magnetic attraction.     

壳聚糖修饰磁性纳米粒子对BSA的吸附性能

采用化学共沉淀法制备磁性Fe3O4纳米粒子,以（3-氯丙基）三甲氧基硅烷为偶联剂将壳聚糖共价键合到磁性Fe3O4纳米粒子的表面,通过红外光谱（FTIR）、X射线衍射（XRD）、扫描电子显微镜（SEM）及热重分析（TGA）对其进行了表征。主要研究了不同影响因素（吸附时间、pH值、牛血清白蛋白浓度）下壳聚糖修饰的磁性纳米粒子对牛血清白蛋白（BSA）的吸附性能。结果得到壳聚糖修饰的磁性Fe3O4纳米粒子粒径为20 nm左右,壳聚糖在磁性Fe3O4纳米粒子表面的接枝率为15.40%。研究表明：在不同条件下,与未修饰的磁性Fe3O4纳米粒子相比,经壳聚糖修饰的Fe3O4纳米粒子对BSA均表现出较强的吸附能力。     

Functionalization of inorganic nanoparticles for bioimaging applications

Modern biomedical imaging technologies have led to significant advances in diagnosis and therapy. Because most disease processes occur at the molecular and cellular levels, researchers continue to face challenges in viewing and understanding these processes precisely and in real time. The ideal imaging resolution would be in nanometers, because most biological processes take place on this length scale. Therefore, the functionalization of nanoparticles (NPs) and their use in therapeutic and diagnostic applications are of great interest. Molecular and cellular imaging agents made from inorganic NPs have been developed to probe such biological events noninvasively. The conjugation of tiny NPs with specific biomolecules allows researchers to target the desired location, reduce overall toxicity, and boost the efficiency of the imaging probes. In this Account, we review recent research on the functionalization of NPs for bioimaging applications. Several types of NPs have been employed for bioimaging applications, including metal (Au, Ag), metal oxide (Fe(3)O(4)), and semiconductor nanocrystals (e.g. quantum dots (QDs) and magnetic quantum dots (MQDs)). The preparation of NPs for bioimaging applications can include a variety of steps: synthesis, coating, surface functionalization, and bioconjugation. The most common strategies of engineering NP surfaces involve physical adsorption or chemisorption of the desired ligands onto the surface. Chemisorption or covalent linkages are preferred, and the coated NPs should possess high colloidal stability, biocompatibility, water solubility, and functional groups for further bioconjugation. Many of the functionalization techniques that have been reported in the literature suffer from limitations such as complex synthesis steps, poor biocompatibility, low stability, and hydrophobic products. Coating strategies based on chemisorption and ligand exchange often provide a better way to tailor the surface properties of NPs. After conjugation with the appropriate targeting ligands, antibodies, or proteins, the NPs may exhibit highly selective binding, making them useful for fluorescence imaging, magnetic resonance imaging (MRI), positron emission tomography (PET) imaging, and multimodal imaging.