磁性阳离子淀粉微球的制备及吸附性能研究

以淀粉、醚化剂为原料,氢氧化钠为催化剂,采用半干法合成了阳离子淀粉;再以阳离子淀粉、氯化亚铁、氯化铁为原料采用混合共沉淀磁化法制得了磁性阳离子淀粉微球,并对产品进行形貌及红外表征。结果表明:制备的磁性阳离子淀粉微球呈不规则球形、表面粗糙、平均粒径为20nm。以甲基橙、次甲基蓝和重铬酸钾为客体分子,测定了磁性阳离子淀粉微球的吸附性能,结果表明:磁性阳离子淀粉微球吸附性能优良,吸附效率可达90%,同时具有磁性,易于实现磁分离。     

磁性淀粉微球对Ni(Ⅱ)吸附性能的研究

研究了磁性淀粉微球对Ni(Ⅱ)的吸附性能。考查了在常温条件下,反应时间、Ni(Ⅱ)的初始浓度、磁性淀粉微球的用量等对吸附性能的影响。探讨了磁性淀粉微球对Ni(Ⅱ)的吸附热力学和吸附动力学行为。结果表明:Ni(Ⅱ)为80mg/L,磁性淀粉微球用量为30mg时,在常温下经过80min的振荡吸附,磁性淀粉微球对Ni(Ⅱ)饱和吸附量达到11.69mg/g;吸附热力学表明磁性淀粉微球对Ni(Ⅱ)的吸附行为符合Freundlich方程;磁性淀粉微球对Ni(Ⅱ)离子的吸附过程可用准一级和准二级动力学模型进行模拟,但更符合二级动力学方程。     

锰锌铁磁性复合微球的制备及对头孢噻肟钠的吸附性研究

采用反向悬浮聚合法,以自制的锰锌铁氧体和四氧化三锰磁性颗粒为核,以淀粉为壳,制备磁性复合微球。利用磁天平(CTP)、扫描电镜(SEM)、红外光谱(IR)及紫外分光光度计(UV-Visible)对微球进行表征。以头孢噻肟钠(CTX)针剂为吸附对象考察微球对药物的吸附量。结果表明,磁性复合微球球形规整,分散性好,四氧化三锰磁性淀粉微球的交联度和磁含量均较锰锌铁(Mn-Zn ferrite)氧体磁性淀粉微球的高,对头孢噻肟钠的饱和吸附量为9.8 mg/g。     

β-环糊精/丁二酸酐共聚高分子磁性微球的制备及其体外释药性能研究

以油酸低温水洗改性制备的磁性四氧化三铁纳米粒子为核,以β-环糊精（β-CD）、丁二酸酐（SA）为主要原料,采用反相乳液聚合法制备了β-环糊精/丁二酸酐共聚高分子磁性微球。分析和探讨了丁二酸酐接枝的磁性β-CD微球结构、不同pH值下的溶胀性能及磁响应性能,并以水杨酸为模型药物进行了微球载药的体外释药性能研究。结果表明：该微球具有pH值敏感性和磁响应性,可以用作药物缓控释系统的载体材料。     

磁性高分子复合微球的研究进展

磁性高分子复合微球是粒径在纳米级至微米级,通过适当方法使有机高分子与无机磁性物质复合起来形成的具有一定磁性及特殊结构的微球。磁性高分子复合微球兼具高分子材料的功能特性和无机纳米粒子的磁响应性,可以在外加磁场作用下快速方便的分离。因此,磁性高分子微球作为一种新型的复合功能材料,在生物化学、靶向药物、化学工业、分离工程、水处理等诸多领域显示出了广泛的应用前景。本论文主要综述了磁性高分子复合微球的制备方法和应用领域,并对前景和存在的问题进行了分析和展望。     

磁性高分子微球固定化酶的制备及应用

利用磁性高分子微球通过化学反应固定化酶,可以借助外部磁场方便地分离回收固定化酶,将固定化酶放入磁场稳定的流动床反应器中还可以减少持续反应体系中的操作.简要地介绍了磁微球的制备方法,包括包埋法、分散聚合、乳液聚合和悬浮聚合,对磁性微球固定化酶的制备方法和原理进行了探讨,论述了磁性高分子微球固定化酶的特点及应用.     

水溶性壳聚糖及磁性壳聚糖微球的制备

以废弃蟹壳为原料制备出了高脱乙酰度壳聚糖和脱乙酰度50%的水溶性壳聚糖,通过电位滴定、红外光谱等对产物的脱乙酰度、功能基团作了表征,测定了产物的黏度,结果表明制备的水溶性壳聚糖的动力黏度为82.9 mPa.s。以0.01 mol/L硝酸钴和0.02 mol/L硝酸铁的混合溶液,采用微乳液法制备了纳米铁酸钴,以水溶性壳聚糖为原料制备了壳聚糖/纳米铁酸钴复合微球,TEM结果显示该磁性壳聚糖微球为规则球形,粒径13μm左右,分散性好。     

环氧化偶联剂修饰纳米磁性二氧化硅微球的制备及其表征

以核壳结构的SiO2磁性微球为载体,表面修饰环氧化基团,为进一步应用于多官能团修饰提供基础。采用酯缩合法制备出磁性微球,并利用透射电镜、场发射扫描电镜、红外光谱仪、激光粒度仪、热分析仪和振动样品磁强计分别对微球的形貌、粒度分布、化学成分和磁性能进行了表征。制备的环氧化SiO2磁性微球核壳结构明显,粒径分布在200 nm左右,环氧化功能基在保证微球粒径大小的情况下成功结合在微球表面,并保持了磁性微球的超顺磁性。采用该方法制备的环氧化核壳型磁性二氧化硅微球性质稳定,为磁性微球进一步功能化提供了可能,是一种优异的生物磁性材料载体。     

木薯淀粉磁性微球的结构表征及其对溶菌酶的吸附性能

磁性微球是高分子材料与磁性物质通过一定作用复合而成的一类具有特殊功能的磁性高分子微球。以木薯淀粉为原材料,复合共沉淀法制备的改性磁流体Fe₃O₄,采用两步法(化学交联法)制备木薯淀粉磁性微球。利用傅里叶变换红外光谱仪、X射线衍射仪、同步热分析仪、扫描电镜、激光粒度仪、磁天平等对其性能及结构进行表征并研究其对溶菌酶的吸附行为。通过单因素法考察磁性微球用量、溶液pH值、吸附温度、吸附时间对吸附率的影响,并采用准一级动力学模型和准二级动力学模型研究其吸附动力学。结果表明:制备的木薯淀粉磁性微球Fe₃O₄含量为19.71%,D₅₀(中位径)为15.40μm,磁化率为1.571×10^-3cm³/g,形貌规整;在微球用量为1.25g,溶液pH=10,吸附温度为25℃,吸附时间为80min时,微球对溶菌酶的吸附率最高,达到84.67%。以相关系数R²为参考,准二级动力学模型(R²=0.99993)较准一级动力学模型(R²=0.99174)、颗粒内扩散模型(R²=0.69996)能更好描述木薯淀粉磁性微球对溶菌酶的吸附行为。     

磁性两性淀粉复合微球的制备及吸附性能研究

以玉米淀粉和环氧丙烷为原料,制备了交联淀粉,接着采用半干法合成了高取代度的磁性两性淀粉。然后以两性淀粉、FeCl_2和FeCl_3为原料,采用混合共沉淀法制备了磁性两性淀粉复合微球。对复合微球进行了IR、SEM、VSM表征,结果表明:复合微球呈不规则球形、表面粗糙、平均粒径为20nm,同时具有超顺磁性,易于实现磁分离。以甲基橙和次甲基蓝为客体分子,测定了磁性两性淀粉复合微球的吸附性能并优化了合成条件。由甲基橙的吸附效果得出制备阳离子淀粉的最佳条件为:淀粉5g,NaOH 0.98g,醚化剂2.85g,水占体系25%,80℃下反应2.5h。由次甲基蓝的吸附效果得出制备阴离子淀粉的最佳条件为:阳离子淀粉5g,碱0.36g,氯乙酸钠0.87g,60℃下反应2h。当淀粉与氧铁比例不超过1∶1时,磁性两性淀粉复合微球对甲基橙及次甲基蓝的吸附率都接近100%。当超过这一比例时,吸附率有所下降。     

磁力旋流器磁系的磁场分析

设计了一种中心吸附铁化合物的磁力旋流器，利用试验和数值模拟的方法，对比分析了磁力旋流器磁场强度和分离性能。在试验中，简化了磁力旋流器磁系的结构，改变导磁铁片厚度、铁芯结构、磁系结构等参数，分析磁系对含铁化合物的吸附能力。利用数值模拟方法得到磁系的磁场强度，为分离能力预测提供依据。结果表明：磁场强度与导磁铁片的厚度成反比，随着导磁铁片厚度增大，磁场强度减小，磁力旋流器对铁化合物颗粒的吸附能力减弱，试验中导磁铁片的厚度为2mm时分离效果最好；铁棒铁芯磁系与铁管铁芯磁系相比具有更大的磁场强度；挤压式磁系与普通磁系相比具有更大的磁场强度。导磁铁片厚度的增大会使磁系端面漏磁量减少，铁芯侧面漏磁量增大；铁棒铁芯磁系的漏磁量相对较小，挤压式磁系的漏磁相对较小。     

磁屏蔽效应对磁场除垢防垢效果的影响

在磁场除垢防垢应用中,管道材料性质的差异会导致流体介质内部的真实磁场大小与理论值存在一定偏差,即磁屏蔽现象,这会大大影响磁处理效果。因此,采用对照试验方法建立两套装置,研究螺线管缠绕段材料分别为铁管和塑料管时,磁屏蔽效应对磁处理效果的影响。试验结果表明,减小磁屏蔽效应,电子除垢仪的除垢、防垢及缓蚀效果得到了提升。     

磁性催化剂反应器耦合磁分离装置

反应磁分离耦合装置兼具化学反应和流固相分离的功能,有助于提高反应效率、降低分离能耗、缩短工艺流程和避免催化剂磨损流失。综述近年来反应磁分离耦合装置的研究进展,流化态耦合磁分离装置包括磁稳流化床反应器和流化床耦合旋流磁分离装置,悬浮态耦合磁分离装置包括磁分离耦合悬浮态光催化反应器和釜式反应器耦合磁分离装置。指出磁性催化剂反应器和磁分离耦合装置应用中需要解决的关键问题是:规范生产适用于磁性催化剂反应器耦合磁分离装置的磁性催化剂以及构建磁性催化剂反应器耦合磁分离装置过程中必须引入磁场发生器。     

磁絮凝膜过滤工艺中附加磁场强化清洗

基于磁强化絮凝膜过滤(MEFMF)工艺中磁絮体和含磁滤饼层的特性,设计了在线(on-line)和离线(off-line)磁强化清洗(MEC)工艺.在磁场和曝气剪切的协同作用下,含磁滤饼层脱离膜纤维表面,膜通量恢复率较常规物理清洗(RC)明显提高.在离线磁强化清洗时,设计反洗装置中心的磁感应强度为6 mT,曝气强度为500 L·m^-2·min^-1,控制清洗时间为5 min,维持反洗压力0.04 MPa,可达到最佳的膜清洗效果,通量恢复率达97%以上.在外加磁场强化清洗过程中,滤饼层中的磁种发生磁化作用,滤饼层表现出微弱的宏观磁性,在磁场的作用下向磁极运动,使得膜通量恢复率明显提高.此外,在MEFMF工艺中采用间歇磁强化清洗,可以更加有效地去除引起不可逆膜污染的胶体和有机物,降低膜污染速率,减缓膜污染.     

Development of high-performance magnetic thin film for high-density magnetic recording

This overview describes our recent study on fabrication processes of high-performance magnetic thin films for high-density magnetic recording. Particularly, it is emphasized that electrochemical processes play significant roles in fabricating the recording heads and media used for the high-density recording. Newly developed electrodeposition methods for fabricating CoNiFe and CoFe soft magnetic thin films with high-saturation magnetic flux density are shown, and the key points for obtaining them are highlighted. It is summarized that the effective seedlayers for the sputter-deposited [Co/Pd]_n multilayered films, which are promising candidates as magnetic recording media with strong perpendicular magnetic anisotropy for the high-density magnetic recording, have been developed. We have recently succeeded in developing the novel electroless deposition methods for the CoNiFe-based soft magnetic underlayers of double-layered perpendicular magnetic recording media and for the patterned medium consisting of CoNiP magnetic nano-dot arrays, which are briefly explained.     

Theranostic magnetic nanoparticles

Early detection and treatment of disease is the most important component of a favorable prognosis. Biomedical researchers have thus invested tremendous effort in improving imaging techniques and treatment methods. Over the past decade, concepts and tools derived from nanotechnology have been applied to overcome the problems of conventional techniques for advanced diagnosis and therapy. In particular, advances in nanoparticle technology have created new paradigms for theranostics, which is defined as the combination of therapeutic and diagnostic agents within a single platform. In this Account, we examine the potential advantages and opportunities afforded by magnetic nanoparticles as platform materials for theranostics. We begin with a brief overview of relevant magnetic parameters, such as saturation magnetization, coercivity, and magnetocrystalline anisotropy. Understanding the interplay of these parameters is critical for optimizing magnetic characteristics needed for effective imaging and therapeutics, which include magnetic resonance imaging (MRI) relaxivity, heat emission, and attractive forces. We then discuss approaches to constructing an MRI nanoparticle contrast agent with high sensitivity. We further introduce a new design concept for a fault-free contrast agent, which is a T1 and T2 dual mode hybrid. Important capabilities of magnetic nanoparticles are the external controllability of magnetic heat generation and magnetic attractive forces for the transportation and movement of biological objects. We show that these functions can be utilized not only for therapeutic hyperthermia of cancer but also for controlled release of cancer drugs through the application of an external magnetic field. Additionally, the use of magnetic nanoparticles to drive mechanical forces is demonstrated to be useful for molecular-level cell signaling and for controlling the ultimate fate of the cell. Finally, we show that targeted imaging and therapy are made possible by attaching a variety of imaging and therapeutic components. These added components include therapeutic genes (small interfering RNA, or siRNA), cancer-specific ligands, and optical reporting dyes. The wide range of accessible features of magnetic nanoparticles underscores their potential as the most promising platform material available for theranostics.     

The heating effect of iron-cobalt magnetic nanofluids in an alternating magnetic field: application in magnetic hyperthermia treatment

In this research, FeCo alloy magnetic nanofluids were prepared by reducing iron(III) chloride hexahydrate and cobalt(II) sulfate heptahydrate with sodium borohydride in a water/CTAB/hexanol reverse micelle system for application in magnetic hyperthermia treatment. X-ray diffraction, electron microscopy, selected area electron diffraction, and energy-dispersive analysis indicate the formation of bcc-structured iron-cobalt alloy. Magnetic property assessment of nanoparticles reveals that some samples are single-domain superparamagnetic, while others are single- or multi-domain ferromagnetic. The stability of the magnetic fluids was achieved by using a CTAB/1-butanol surfactant bilayer. Results of Gouy magnetic susceptibility balance experiments indicate good stability of FeCo nanoparticles even after dilution. The inductive properties of corresponding magnetic fluids including temperature rise and specific absorption rate were determined. Results show that with increasing of the nanoparticle size in the single-domain size regime, the generated heat increases, indicating the significant effect of the hysteresis loss. Finally, the central parameter controlling the specific absorption rate of nanoparticles was introduced, the experimental results were compared with those of the Stoner-Wohlfarth model and linear response theory, and the best sample for magnetic hyperthermia treatment was specified.     

Near field and magnetic field generator for thermal assisted magnetic recording

We fabricated a generator that produces optical near field and magnetic filed in a nanometer area for achievement of thermally assisted magnetic recording. The generator consists of an embedded wire with a bottleneck structure on a SiO₂ substrate. The magnetic field is mainly generated around the bottleneck structure by feeding current through the wire. The near field is produced on an edge of the narrow wire by focusing a laser beam on the bottleneck structure through the backside of the substrate. The generator is anticipated as application to control ordering, chirality, and phase transition of diamagnetic materials in a nano-area. We confirmed the three-dimentional localization of near field in the nanometer size around the bottleneck structure by means of a near field scanning optical microscope.     

二次表面修饰制备工艺的磁粉对磁性流体的性能提高

通过二次表面修饰技术制备磁粉,来对现有磁粉制备技术进行改进,进而提高现有磁粉的整体性能,并研究二次表面修饰技术制备磁粉对磁粉及磁性流体性能的影响。     

Reversible thermoflocculation of magnetic core-shell particles induced by remote magnetic heating

We developed multifunctional magnetic polymer brushes with a tailorable thermoresponsive dispersion behavior that can be activated by AC magnetic fields. Via surface-initiated ATRP, magnetic core-shell nanoparticles are obtained that are composed of nanosized superparamagnetic iron oxide cores and a copolymer shell. The shell consists of oligo(ethylene glycol) methylether methacrylate (OEGMA) and methoxyethyl methacrylate (MEMA) copolymers that show a lower critical solution temperature (LCST) in water.The hybrid structures are easily dispersible in water at room temperature, and show a reversible thermoflocculation at critical temperatures adjustable by the copolymer composition. The phase separation can alternatively be initiated and recorded by magnetic heating caused by magnetic losses in AC fields. This method offers a convenient way for the remote-controlled heating and agglomeration of disperse systems.