Mishra Sushanta Kumar, Kumar B S Hemanth, Khushu Subash, Tripathi Rajendra P, Gangenahalli Gurudutta
NMR Research Centre, Institute of Nuclear Medicine and Allied Sciences (INMAS), DRDO, New Delhi, India.
Division of Stem Cells and Gene Therapy Research, Institute of Nuclear Medicine and Allied Sciences (INMAS), DRDO, New Delhi, India.
Contrast Media Mol Imaging. 2016 Sep;11(5):350-361. doi: 10.1002/cmmi.1698. Epub 2016 May 27.
Synthesis of a contrast agent for biomedical imaging is of great interest where magnetic nanoparticles are concerned, because of the strong influence of particle size on transverse relaxivity. In the present study, biocompatible magnetic iron oxide nanoparticles were synthesized by co-precipitation of Fe and Fe salts, followed by surface adsorption with reduced dextran. The synthesized nanoparticles were spherical in shape, and 12 ± 2 nm in size as measured using transmission electron microscopy; this was corroborated with results from X-ray diffraction and dynamic light scattering studies. The nanoparticles exhibited superparamagnetic behavior, superior T relaxation rate and high relaxivities (r = 18.4 ± 0.3, r = 90.5 ± 0.8 s mM , at 7 T). MR image analysis of animals before and after magnetic nanoparticle administration revealed that the signal intensity of tumor imaging, specific organ imaging and whole body imaging can be clearly distinguished, due to the strong relaxation properties of these nanoparticles. Very low concentrations (3.0 mg Fe/kg body weight) of iron oxides are sufficient for early detection of tumors, and also have a clear distinction in pre- and post-enhancement of contrast in organs and body imaging. Many investigators have demonstrated high relaxivities of magnetic nanoparticles at superparamagnetic iron oxide level above 50 nm, but this investigation presents a satisfactory, ultrasmall, superparamagnetic and high transverse relaxivity negative contrast agent for diagnosis in pre-clinical studies. Copyright © 2016 John Wiley & Sons, Ltd.
就磁性纳米颗粒而言，由于颗粒大小对横向弛豫率有很大影响，生物医学成像造影剂的合成备受关注。在本研究中，通过共沉淀铁盐和亚铁盐，随后用还原葡聚糖进行表面吸附，合成了生物相容性磁性氧化铁纳米颗粒。合成的纳米颗粒呈球形，使用透射电子显微镜测量其尺寸为12±2纳米；这与X射线衍射和动态光散射研究的结果相符。这些纳米颗粒表现出超顺磁性行为、优异的T弛豫率和高弛豫性（在7T时，r2 = 18.4±0.3，r1 = 90.5±0.8 s mM-1）。对动物在给予磁性纳米颗粒前后进行的磁共振图像分析表明，由于这些纳米颗粒具有很强的弛豫特性，肿瘤成像、特定器官成像和全身成像的信号强度能够清晰区分。极低浓度（3.0毫克铁/千克体重）的铁氧化物就足以早期检测肿瘤，并且在器官和身体成像的增强前后对比中也有明显区别。许多研究人员已经证明，超顺磁性氧化铁水平高于50纳米的磁性纳米颗粒具有高弛豫性，但本研究提供了一种令人满意的、超小的、超顺磁性且具有高横向弛豫性的阴性造影剂，用于临床前研究中的诊断。版权所有© 2016约翰威立父子有限公司。
