Ma Hui-li, Qi Xian-rong, Maitani Yoshie, Nagai Tsuneji
Department of Pharmaceutics, School of Pharmaceutical Sciences, Peking University, Beijing 100083, China.
Int J Pharm. 2007 Mar 21;333(1-2):177-86. doi: 10.1016/j.ijpharm.2006.10.006. Epub 2006 Oct 7.
SPION with appropriate surface chemistry have been widely used experimentally for numerous in vivo applications. In this study, SPION stabilized by alginate (SPION-alginate) were prepared by a modified coprecipitation method. The structure, size, morphology, magnetic property and relaxivity of the SPION-alginate were characterized systematically by means of XRD, TEM, ESEM, AFM, DLS, SQUID magnetometer and MRI, respectively, and the interaction between alginate and iron oxide (Fe(3)O(4)) was characterized by FT-IR and AFM. The results revealed that typical iron oxide nanoparticles were Fe(3)O(4) with a core diameter of 5-10 nm and SPION-alginate had a hydrodynamic diameter of 193.8-483.2 nm. From the magnetization curve, the Ms of a suspension of SPION-alginate was 40 emu/g, corresponding to 73% of that of solid SPION-alginate. This high Ms may be due to the binding of Fe(3)O(4) nanoparticles to alginate macromolecule strands as visually confirmed by AFM. SPION-alginate of several hundred nanometers was stable in size for 12 months at 4 degrees C. Moreover, T1 relaxivity and T2 relaxivity of SPION-alginate in saline (1.5 T, 20 degrees C) were 7.86+/-0.20 s(-1) mM(-1) and 281.2+/-26.4 s(-1) mM(-1), respectively.
具有合适表面化学性质的超顺磁性氧化铁纳米粒子（SPION）已在众多体内应用实验中广泛使用。在本研究中，通过改进的共沉淀法制备了由海藻酸钠稳定的SPION（SPION-海藻酸钠）。分别利用X射线衍射（XRD）、透射电子显微镜（TEM）、环境扫描电子显微镜（ESEM）、原子力显微镜（AFM）、动态光散射（DLS）、超导量子干涉仪磁强计（SQUID magnetometer）和磁共振成像（MRI）系统地表征了SPION-海藻酸钠的结构、尺寸、形态、磁性和弛豫率，并用傅里叶变换红外光谱（FT-IR）和AFM表征了海藻酸钠与氧化铁（Fe(3)O(4)）之间的相互作用。结果表明，典型的氧化铁纳米粒子为Fe(3)O(4)，其核心直径为5-10nm，SPION-海藻酸钠的流体动力学直径为193.8-483.2nm。从磁化曲线可知，SPION-海藻酸钠悬浮液的饱和磁化强度（Ms）为40emu/g，相当于固体SPION-海藻酸钠的73%。这种高Ms可能是由于AFM直观证实的Fe(3)O(4)纳米粒子与海藻酸钠大分子链的结合。几百纳米的SPION-海藻酸钠在4℃下尺寸稳定12个月。此外，SPION-海藻酸钠在生理盐水（1.5T，20℃）中的T1弛豫率和T2弛豫率分别为7.86±0.20s(-1) mM(-1)和281.2±26.4s(-1) mM(-1)。
