CSIRO Molecular and Health Technologies, Private Bag 10, Clayton South MDC, VIC 3169, Australia.
Langmuir. 2010 Feb 16;26(4):2383-91. doi: 10.1021/la902845j.
Gadolinium oleate has been added at various concentrations to a Myverol inverse bicontinuous cubic phase forming system, and the potential of these systems as magnetic resonance imaging (MRI) contrast agents has been investigated. Differential scanning calorimetry (DSC), small-angle X-ray scattering (SAXS), and cryo-transmission electron microscopy (cryo-TEM) measurements on the Gd oleate/Myverol systems indicate that Gd oleate is at least partially incorporated within the cubic phase of Myverol. However, at Gd oleate concentrations greater than 1 wt %, partial phase separation of the system may occur with the formation of a Gd-oleate-rich lamellar phase as well as the cubic phase. Bulk Gd oleate/Myverol mixtures can be dispersed into stable colloidal dispersions. SAXS and cryo-TEM measurements on these dispersions indicate that the presence of Gd oleate in the Myverol system prevents the formation of cubosomes from the bulk cubic phase. Instead, the dispersion consists of putative Gd-oleate-rich nonswelling lamellar nanoparticles as well as colloidal particles lacking ordered internal structure. In vitro studies on these dispersions demonstrated that the relaxivity of select Gd oleate/Myverol systems is much higher than that of pure Gd oleate, exemplifying the promise of this system type for magnetic resonance imaging. The highest water proton relaxivities (r(1) = 34.2 mM(-1) s(-1) and r(2) = 27.3 mM(-1) s(-1) at 20 MHz and room temperature) were obtained at a Gd oleate loading concentration of 1 wt %, with a subsequent decrease in relaxivity with increasing Gd oleate concentration. These maximum relaxivities compare favorably with the relaxivities for the commercial contrast agent, Magnevist (r(1) = 4.91 mM(-1) s(-1) and r(2) = 6.26 mM(-1) s(-1) at 20 MHz and room temperature).
油酸钆已以不同浓度添加到 Myverol 反胶束双连续立方相形成体系中，并研究了这些体系作为磁共振成像（MRI）造影剂的潜力。油酸钆/Myverol 体系的差示扫描量热法（DSC）、小角 X 射线散射（SAXS）和冷冻传输电子显微镜（cryo-TEM）测量表明，油酸钆至少部分掺入 Myverol 的立方相中。然而，在油酸钆浓度大于 1wt%时，体系可能会发生部分相分离，形成富含油酸钆的层状相以及立方相。块状油酸钆/Myverol 混合物可以分散成稳定的胶体分散体。这些分散体的 SAXS 和 cryo-TEM 测量表明，油酸钆在 Myverol 体系中的存在阻止了立方相从块状立方相向立方囊泡的形成。相反，分散体由假定的富含油酸钆的非溶胀层状纳米颗粒以及缺乏有序内部结构的胶体颗粒组成。对这些分散体的体外研究表明，选择的油酸钆/Myverol 体系的弛豫率远高于纯油酸钆，证明了这种体系类型在磁共振成像中的应用前景。在油酸钆负载浓度为 1wt%时，获得了最高的水质子弛豫率（r1=34.2 mM-1 s-1，r2=27.3 mM-1 s-1，在 20 MHz 和室温下），随后随着油酸钆浓度的增加，弛豫率降低。这些最大弛豫率与商业造影剂 Magnevist 的弛豫率（r1=4.91 mM-1 s-1，r2=6.26 mM-1 s-1，在 20 MHz 和室温下）相当。
