纳米磁热复温玻璃化低温保存大鼠肾脏的研究

纳米磁热复温有望解决器官玻璃化低温保存复温的难题。本文测试了氧化铁纳米颗粒在VS55低温保护剂溶液中的胶体稳定性及磁热性能。结果表明,纳米颗粒VS55溶液分散体系即使在玻璃化冷冻磁热复温后,仍在较长时间内保持胶体稳定,且磁热性能随交变磁场电流、纳米颗粒浓度的增加而提升。磁共振成像结果显示通过灌注能够基本实现纳米颗粒在大鼠肾脏组织中的均匀分布与完全洗脱。肾脏总体结构在玻璃化冷冻磁热复温后保持完整,但磁共振成像显示其内部血管网络可能受到一定程度的损伤。研究结果说明,通过进一步提升磁场强度或纳米颗粒的磁热性能,优化灌注加载流程,有望实现更加快速均匀的复温,从而在不久的将来解决器官玻璃化保存的复温难题。     

影响磁性氧化铁纳米颗粒磁热疗加热效率的因素

磁性纳米颗粒作为产热介质在生物医学方面取得了广泛的应用前景.近年来,新开发的纳米颗粒细胞内疗法更是克服了常规治疗方法的副作用,使治疗效率大大提高.氧化铁纳米颗粒由于其优异的磁性能在磁热疗应用的磁性纳米颗粒中脱颖而出,但存在着在交变磁场下加热效率受限的问题.具有高加热效率受限的磁性纳米粒子是磁热疗的必要条件.本文综述了近...     

静电纺丝制备磁性碳纳米复合纤维及其表征

以聚丙烯腈(PAN)、乙酰丙酮铁(AAI)、N, N-二甲基甲酰胺(DMF)为原料, 采用静电纺丝-煅烧技术成功制备出磁性碳纳米复合纤维。通过TEM分析发现CF900的直径约为130~210 nm, 磁性纳米颗粒均匀地分散在碳纳米纤维中, 并探讨了碳化温度对碳纳米复合纤维磁性能的影响。结果显示: 饱和磁化强度(M_s)和剩余磁化强度(M_r)均随温度的升高而增大, 样品CF900的饱和磁化强度(M_s)高达27.55 A·m²/kg, 比表面积(S_BET)和总孔容积(V_total)达354.0 m²/g和0.315 mL/g。     

热降解法制备纳米磁性物质

描述制备可以在有机溶剂中均匀分散的磁性物,实验采用热降解法制备该纳米磁性物质,通过在高温下使铁盐等铁类复合物分解生成可均匀分散于有机相的产物,方法制备简单,相对于传统的共沉淀法来说具有极大的优越性。     

纳米钴镍铁氧体磁性颗粒的制备

采用共沉淀法和柠檬酸盐法制备钴镍铁氧体磁性颗粒，探索了制备工艺，测定了磁性能。结果表明：CoxNi1-xFe2O4的比饱和磁化强度随着Co含量增大而增强；合理的工艺制度为75℃水浴；NaOH的浓度取3mol/L、过量25%、缓慢滴加；反应时间30min；磁性颗粒粒径为15nm左右；与柠檬酸盐法相比，共沉淀法更为为适宜。     

PLLA-PEG-PLLA/Fe_3O_4磁性微球的制备及性能

以聚乙二醇为引发剂,L-丙交酯为单体,开环聚合得到聚乳酸-聚乙二醇三嵌段共聚物(PLLA-PEG-PLLA),采用溶剂挥发法制备了PLLA-PEG-PLLA/Fe_3O_4磁性微球,并通过扫描电镜对其形态进行了表征。利用振动样品磁强计和Tg研究了微球的磁含量和磁性能,结果发现,相同粒径不同磁含量的磁性微球,磁含量越高,升温速率越快,当磁含量为70.57%时,升温速率最快,能达到磁热疗的有效温度42℃。对于磁含量相同,粒径不同的微粒,粒径越小,升温速率越快,粒径约为10μm时升温速率最快。     

含钙铁氧体磁性生物活性玻璃陶瓷热种子的制备与表征

本工作将钙铁氧体与溶胶-凝胶法制得的生物活性玻璃陶瓷复合,制备了含钙铁氧体磁性生物活性玻璃陶瓷磁热种子。对所制得材料的物相组成、磁性、体外生物活性、磁生热能力及磁热对肿瘤细胞的杀伤效应、组织相容性进行了表征。结果表明,材料主晶相为CaSiO₃、Ca₅(PO₄)₃F和CaFe₂O₄。充磁约8×10⁵ A·m-1时,材料饱和磁化强度约5 A·m²·kg-1,矫顽力约2×10⁴ A·m-1。暴露在342 kHz、1×10³ A/m的交变磁场下,0.1 g材料20 min内即能实现升温约40 ℃。在浸泡入模拟体液中14 d后,材料表面能形成不连续的含有碳酸根生物的活性层。MTT细胞增殖实验显示材料无细胞毒性,MG63细胞能在材料上粘附和生长。将材料与VX2细胞在交变磁场下复合培养20 min,材料周围出现明显的死亡细胞圈。兔肌肉植入实验显示材料组织相容性良好。     

快速热解法制备炭包覆纳米金属磁性颗粒(英文)

以简单金属前躯体为原料通过快速热解法制备炭包覆纳米金属磁性颗粒,通过透射电镜、X-射线衍射、热重-示差扫描同步热分析及振动样品磁强计等对产物形貌、结构、成分与磁性能进行表征。结果表明:采用该方法制备的炭包覆纳米金属磁性颗粒形状为近球形颗粒,粒径均一,其中炭包覆镍纳米磁性颗粒的粒径集中在10nm～30nm范围,炭包覆铁纳米磁性颗粒粒径则在50nm～60nm范围;所制炭包覆纳米金属磁性颗粒在室温下具有顺磁性,其磁性能随金属颗粒含量的变化而改变。该方法有望发展成一种工艺简单,可进行连续工业化生产炭包覆纳米金属磁性颗粒的方法。     

磁性水凝胶作为药物载体的应用研究进展

磁性水凝胶是一类同时具有磁性材料、高分子材料及水凝胶的性质特点的无机/有机复合材料。因具有优良的磁学性能及生物相容性,其作为新一代的药物载体可以实现磁响应、磁靶向及磁热疗等功能,在药物控制释放领域具有广阔的应用前景。对磁性水凝胶的制备方法及其在药物载体领域的研究情况进行了综述,详细介绍了磁性水凝胶作为药物载体的两种药物释放机理(ON/OFF模型及热敏释放原理),及其在磁靶向药物控释、磁热疗和磁共振成像方面的应用研究现状。     

Fe-Ni/NiFe_2O_4纳米复合颗粒的制备与磁性研究

结合共沉淀法和氢气还原法成功制备出FeNi/NiFe2O4纳米复合颗粒,所制备的纳米复合颗粒包含NiFe2O4和Fe-Ni合金,其中Fe-Ni合金具有体心立方和面心立方两种结构。用XRD和TEM对所得样品进行结构分析。用SQUID测量样品在室温时的磁滞回线,发现Fe-Ni/NiFe2O4纳米复合颗粒的矫顽力和饱和磁化强度与制备态NiFe2O4纳米颗粒相比随着退火时间的增加呈现出逐渐增加的趋势。为了进一步研究所制备的纳米复合颗粒的磁性特征,测量退火时间相同而退火温度不同的两个样品在零磁场冷却(ZFC)和带磁场冷却(FC)条件下的M-T曲线。     

Synthesis, characterization and in vitro cytotoxicity of self-regulating magnetic implant material for hyperthermia application

Gd-substituted zinc ferrite nanoparticles with low Curie temperatures (T_c) were synthesized by a chemical co-precipitation method. The magnetic properties and heat generation characteristics of these magnetic nanoparticles were investigated. The T_c of ZnGd_xFe_2 − xO₄ nanoparticles increased with increasing Gd³⁺ substitution, and was ~ 318 K at x = 0.02, which was a suitable Curie temperature for thermal seeds implanted in human body. The study on heat generation ability under external alternating magnetic field showed that the temperatures of these nanoparticles could be safely controlled around T_c without the temperature probe and controller. Furthermore, in vitro cytotoxicity of the ferrite nanoparticles was assessed using MTT assay. The results demonstrated that exposure to the bare ferrite nanoparticles for 48 h resulted in concentration-dependent toxicity. Cell growth inhabitation was observed when 4.0 mg/ml of bare ferrite nanoparticles was used. In contrast, PEG-capped nanoparticles had no significant effect on cell viability at any of the concentrations tested.     

Preparation and Antibacterial Activity of Three-component NiFe_2O_4@PANI@Ag Nanocomposite

A new three-component and magnetically responsive NiFe_2O_4@PANI@Ag nanocomposite has been fabricated by coating of nickel ferrite,NiFe_2O_4,nanoparticles with polyaniline(PANI) and subsequent immobilization of silver nanoparticles onto the surface of polyaniline shell.The as-prepared nanocomposite has been characterized by X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FT-IR),scanning electron microscopy(SEM),and vibrating sample magnetometer(VSM).The saturation magnetization of the NiFe_2O_4core decreases dramatically after coating with polyaniline and silver nanoparticles,however,the nanocomposite NiFe_2O_4@PANI@Ag can be still separated from solution media through magnetic decantation.The antibacterial activity of the synthesized nanocomposite was studied and compared with those of naked NiFe_2O_4,NiFe_2O_4@PANI and some standard antibacterial drugs.     

核壳结构磁性复合纳米粒的制备及研究进展

多功能磁性复合纳米粒在生物医学上具有广泛的应用和巨大的潜力。首先介绍了二氧化硅、金银贵金属和荧光半导体核壳磁性复合纳米粒的应用前景，重点阐述了溶胶-凝胶法、微乳液法、自组装技术和种子生长法在制备核壳结构磁性复合纳米粒中的应用，分析了磁性纳米粒存在的问题，展望了其发展的方向。     

氢等离子体电弧法Mg／TiO2复合纳米粒子的制备与表征

采用氢等离子体电弧法,在H2＋Ar气氛下制备出Mg／TiO2复合纳米粒子．通过X射线衍射仪（XRD）、红外分析（FT—IR）、高分辨透射电镜（HRTEM）对纳米粒子的化学成分、晶体结构和表面形貌进行了分析,发现具有六方形晶体惯态的镁粒子通过表面包覆一层TiO2后形成了球形粒子;分析了其形成过程．热重分析（TGA—SDTA）结果表明,Mg／TiO2复合纳米粒子比纯Mg纳米粒子抗氧化温度提高30～40℃．     

Preparation and Antibacterial Activity of Three-component NiFe204@PANI@Ag Nanocomposite

A new three-component and magnetically responsive NiFe2O4@PANI@Ag nanocomposite has been fabricated by coating of nickel ferrite, NiFe2O4, nanoparticles with polyaniline （PANI） and subsequent immobilization of silver nanoparticles onto the surface of polyaniline shell. The as-prepared nanocomposite has been characterized by X-ray diffraction （XRD）, Fourier transform infrared spectroscopy （FT-IR）, scanning electron microscopy （SEM）, and vibrating sample magnetometer （VSM）. The saturation magnetization of the NiFe2O4 core decreases dramatically after coating with polyaniline and silver nanoparticles, however, the nanocomposite NiFe2O4@PANI@Ag can be still separated from solution media through magnetic decantation. The antibacterial activity of the synthesized nanocomposite was studied and compared with those of naked NiFe2O4, NiFe2O4@PANI and some standard antibacterial drugs.     

POSS/PS纳米复合材料的制备与热性能

以CuCl/2,2'-联吡啶为催化剂,POSS-Cl为引发剂,采用ATRP法制备了POSS/PS纳米复合材料,用FT-IR、1H-NMR、XPS、XRD对产物进行了合成表征,并用DSC、TGA研究了复合材料的热性能.实验结果表明,ATRP法制备POSS/PS核壳型复合材料是可行的,POSS在PS中的分散性较好,POSS的加入对PS的Tg和Td有一定程度的提高.     

SiO_2包覆P(St-4VP)纳米复合粒子的制备与表征

使用功能化的共单体4-乙烯基吡啶(4VP)与苯乙烯共聚,合成了聚(苯乙烯-共-4-乙烯基吡啶)(P(St-4VP))粒子。在NH_4OH/乙醇碱性介质中,溶胶-凝胶法生成的SiO_2纳米粒子包覆在P(St-4VP)粒子表面,得到SiO_2包覆P(St-4VP)纳米复合粒子。随4VP组分增加,所制备的P(St-4VP)/SiO_2纳米复合粒子的壳层表面变得粗糙。P(St-4VP)粒子数随PVP用量增加而增加,因此纳米复合粒子的平均尺寸随PVP用量增加而下降,同时随PVP用量增加形成较平滑的SiO_2壳层。NH_4OH和正硅酸乙酯(TEOS)用量增加,复合粒子的SiO_2壳层表面粗糙程度提高。此外,复合粒子的SiO_2壳层厚度随TEOS用量增加而增加。     

Magnetocaloric effect of (ErxR1−x)Co2 (R = Ho, Dy) for magnetic refrigeration between 20 and 80 K

Two series of RCo₂ compounds, (Er_xHo_1−x)Co₂ and (Er_yDy_1−y)Co₂, were investigated as magnetic refrigerants for hydrogen liquefaction. A large magnetocaloric effect (MCE) was observed just above the Curie temperature (T_c) of these compounds which both undergo a first-order magnetic transition. The isothermal entropy change ΔS and the adiabatic temperature change ΔT_ad of these compounds were larger than those of other Laves-phase materials such as RAl₂ and RNi₂. However, the temperature range of the large MCE for these compounds was limited. It has been shown that T_c increases almost linearly against the de Gennes factor, and can be controlled by changing the concentration of the rare earth elements while maintaining a first-order transition. By measuring the magnetization and heat capacity, we obtained temperature entropy (T–S) diagrams, which are essential for analyzing the magnetic refrigeration cycle. Both series of compounds showed high potential for use in a regenerative thermal cycle, especially as a combination of several compositions to cover a wide temperature range.