MAGNETOFERRITIN - CHARACTERIZATION OF A NOVEL SUPERPARAMAGNETIC MR CONTRAST AGENT
MAGNETOFERRITIN - CHARACTERIZATION OF A NOVEL SUPERPARAMAGNETIC MR CONTRAST AGENT
复制标题
DOI：
10.1002/jmri.1880040343
复制
发表时间：
1994-05-01
影响因子：
4.4
通讯作者：
FRANK, JA
中科院分区：
文献类型：
--
作者：
BULTE, JWM;DOUGLAS, T;FRANK, JA
利用马脾载铁蛋白作为一种新型生物反应环境，制备了一种蛋白质包膜的超顺磁性氧化铁。磁性铁蛋白分子直径约为120埃，由直径为73埃+/- 14的单晶磁铁矿或磁铁矿核组成。除了含有更高分子量的富铁分子外，磁铁蛋白的外观和分子量（450kd）与天然铁蛋白相同；这些分子在外部与它们的前体难以区分，pI（等电点）在4.3-4.6范围内。测量到的超顺磁磁芯的磁矩为每分子13200玻尔磁子，TI和T2的弛豫率（r1和r2）分别为8和175 l mmol-1 （Fe）。分别在体温和临床场强下的秒1。异常高的r2/r1比值22被认为是由理想的核心成分引起的，没有证据表明存在晶体顺磁包裹体。T2弛豫增强可以很好地与场相关的分子磁化相关，由朗之万磁化函数给出，其幂在1.4-1.6范围内。磁性铁蛋白的纳米级仿生蛋白笼作为一种刚性的、方便的基质，可以络合大量的生物活性物质，它可能为选定的细胞位点的特异性靶向提供一种新的模板。
A protein-encaged superparamagnetic iron oxide has been developed and characterized hy using horse spleen apoferritin as a novel bioreactive environment. The roughly spherical magnetoferritin molecules, 120 angstrom in diameter, are composed of a monocrystalline maghemite or magnetite core 73 angstrom +/- 14 in diameter. Except for the additional presence of iron-rich molecules of higher molecular weight, the appearance and molecular weight (450 kd) of magnetoferritin are identical to that of natural ferritin; the molecules are externally indistinguishable from their precursor, with a pI (isoelectric point) in the range 4.3-4.6. The measured magnetic moment of the superparamagnetic cores is 13,200 Bohr magnetons per molecule, with TI and T2 relaxivities (r1 and r2) of 8 and 175 L.mmol-1 (Fe).sec-1, respectively, at body temperature and clinical field strengths. The unusually high r2/r1 ratio of 22 is thought to arise from ideal core composition, with no evidence of crystalline paramagnetic inclusions. T2 relaxation enhancement can be well correlated to the field-dependent molecular magnetization, as given by the Langevin magnetization function, raised to a power in the range 1.4-1.6. With its nanodimensional biomimetic protein cage as a rigid, convenient matrix for complexing a plethora of bioactive substances, magnetoferritin may provide a novel template for specific targeting of selected cellular sites.