中文摘要：

四氧化三铁纳米颗粒（Fe3O4-NPs）在生物医学领域有着广泛的应用。通过同步辐射真空紫外圆二色谱（SRCD）和紫外可见（UV-Vis）吸收谱技术研究了Fe3O4纳米颗粒的粒径（10nm和40nm）对细胞色素C（Cytc）结构的影响。结果表明，随着Fe3O4-NPs颗粒物浓度的增大，Cytc在408nm处的吸光度值逐澎下降。SRCD结果显示Cytc与Fe3O4-NPs作用后，蛋白的α螺旋含量减少，β折叠含量增加；Fe3O4-NPs与CytC的作用强度具有尺寸依赖性，小尺寸的Fe3O4-NPs作用更为明显。

英文摘要：

Supermagnetic iron oxide nanoparticles （Fe3O4-NPs） can promote many attractive functions in biomedical fields. In this study, the interaction of Fe3O4NPs （10 nm and 40 nm） with cytochrome c （Cyt c） was studied by synchrotron radiation circular dichroism （SRCD） and UV-Vis spectroscopy. After adding Fe3O4 NPs in the Cyt c solution, the intensity of the Soret band （408 nm） decreased significantly. The SRCD characterization showed the loss of the α-helix structure and the occurrence of cytochrome c unfolding after Fe3O3-NPs treatment, meanwhile, the 10 nm Fe3O3-NPs had more prominent effects than the 40 nm ones. The results showed significant size-depended and dose-depended effects. This study provides important insight into the interaction of Fe3O4 NPs with cytochrome c, which may be a useful guideline for further use of Fe3O4 NPs.