摘要：An atomic layer deposition （ALD） method has been employed to synthesize Fe3O4/graphene and Ni/graphene composites. The structure and microwave absorbing properties of the as-prepared composites are investigated. The surfaces of graphene are densely covered by Fe3O4 or Ni nanoparticles with a narrow size distribution, and the magnetic nanoparticles are well distributed on each graphene sheet without significant conglomeration or large vacancies. The coated graphene materials exhibit remarkably improved electromagnetic （EM） absorption properties compared to the pristine graphene. The optimal reflection loss （RL） reaches -46.4 dB at 15.6 GHz with a thickness of only 1.4 mm for the Fe3O4/graphene composites obtained by applying 100 cycles of Fe2O3 deposition followed by a hydrogen reduction. The enhanced absorption ability arises from the effective impedance matching, multiple interfacial polarization and increased magnetic loss from the added magnetic constituents. Moreover, compared with other recently reported materials, the composites have a lower filling ratio and smaller coating thickness resulting in significantly increased EM absorption properties. This demonstrates that nanoscale surface modification of magnetic particles on graphene by ALD is a very promising way to design lightweight and high-efficiency microwave absorbers.

摘要：目的:构建针对人基质金属蛋白酶-9(MMP-9)小干扰RNA(siRNA)表达载体,并观察其对川崎病(KD)血清诱导的血管内皮细胞MMP-9高表达的干扰效果。方法:依据siRNA设计原则设计两对MMP-9基因的特异性干扰序列,体外分别合成两端含BamH Ⅰ和Hind Ⅲ酶切位点的编码短发夹RNA序列的DNA单链,退火后与pSilencer3.1-HI neo线性质粒连接,转化DH5α感受态菌株,筛选阳性克隆,提取质粒进行双酶切及琼脂糖电泳鉴定。阳性重组质粒测序。将构建的两个MMP-9 siRNA质粒以KD血清作为诱导因子,用脂质法转染内皮细胞ECV-304,应用RT-PCR法测定各实验组血管内皮细胞MMP-9mRNA表达、Western blot检测各组MMP-9蛋白表达情况,对所构建的MMP-9 siRNA质粒进行效应检测。结果:DNA测序证实合成的并被克隆入pSilencer3.1-HI neo表达质粒siRNA插入序列与设计完全符合。KD血清组MMP-9蛋白及mRNA表达水平均较正常血清组明显升高(P<0.05);而所构建的两个MMP-9 siRNA及人血丙种球蛋白均能显著抑制KD血清的上述诱导作用(P<0.05)。结论:成功构建的两个MMP-9 siRNA比人血丙种球蛋白更能高效、特异地抑制MMP-9的表达,为进一步研究MMP-9基因对KD冠状动脉病变的影响及其临床应用奠定了基础。