Magnetic nanophases nucleated within horse spleen apoferritin, under in vivo physiological conditions and in vitro reconstitution, were characterized by Mossbauer spectroscopy in lyophilized form. Mossbauer spectra at 80 K indicate that for the in vivo produced ferritin the presence of phosphates within the iron biomineral core results in larger quadrupole splittings, at interior and surface sites, 0.62 mm/s and 1.06 mm/s, respectively, as compared to 0.56 mm/s and 0.75 mm/s for the reconstituted ferritin. Data collected at lower temperatures give blocking temperatures of 55 and 40 K for in vitro and in vivo samples. At 4.2 K, both samples give similar hyperfine field values for the interior (495 kOe) and surface (450 kOe) iron sites. The temperature dependence of the hyperfine fields at the interior sites is consistent with the collective magnetic excitations model, due to the precession of the particle's magnetization about the anisotropy axis. In contrast, a marked decrease in the hyperfine field at surface sites with increasing temperature indicates a more complex spin excitation energy landscape at the surface.
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机译：在体内生理条件和体外重构下，在马脾脱铁铁蛋白内成核的磁性纳米相通过冻干形式的莫斯鲍尔光谱法表征。 80 K的Mossbauer光谱表明，对于体内产生的铁蛋白，铁矿物质核心内磷酸盐的存在导致内部和表面部位的较大四极分裂，分别为0.62 mm / s和1.06 mm / s，而0.56 mm / s和0.75 mm / s的重组铁蛋白。在较低温度下收集的数据得出体外和体内样品的阻断温度分别为55和40K。在4.2 K时，两个样品在内部（495 kOe）和表面（450 kOe）铁位点都给出相似的超精细场值。由于粒子围绕各向异性轴的磁化的进动，内部场所的超精细场对温度的依赖性与集体磁激发模型一致。相反，随着温度的升高，表面部位的超精细场显着下降，表明表面处的自旋激发能态更为复杂。
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