Department of chemistry and CSGI, University of Florence, Via della Lastruccia 3, Sesto Fiorentino, 50019 Florence, Italy.
Nanoscale. 2018 Feb 15;10(7):3480-3488. doi: 10.1039/c7nr08478a.
The inclusion of superparamagnetic iron oxide nanoparticles (SPIONs) in lipid mesophases is a promising strategy for drug-delivery applications, combining the innate biocompatibility of lipid architectures with SPIONs' response to external magnetic fields. Moreover, the organization of SPIONs within the lipid scaffold can lead to locally enhanced SPIONs concentration and improved magnetic response, which is key to overcome the current limitations of hyperthermic treatments. Here we present a Small-Angle X-ray Scattering (SAXS) structural investigation of the thermotropic and magnetotropic behavior of glyceryl monooleate (GMO)/water mesophases, loaded with hydrophobic SPIONs. We prove that even very low amounts of SPIONs deeply alter the phase behavior and thermotropic properties of the mesophases, promoting a cubic to hexagonal phase transition, which is similarly induced upon application of an Alternating Magnetic Field (AMF). Moreover, in the hexagonal phase SPIONs spontaneously self-assemble within the lipid scaffold into a linear supraparticle. This phase behavior is interpreted in the framework of the Helfrich's theory, which shows that SPIONs affect the mesophase both from a viscoelastic and from a structural standpoint. Finally, the dispersion of these cubic phases into stable magnetic colloidal particles, which retain their liquid crystalline internal structure, is addressed as a promising route towards magneto-responsive drug-delivery systems (DDS).
超顺磁性氧化铁纳米粒子（SPIONs）在类脂中间相中的包含物是一种有前途的药物输送应用策略，它结合了类脂结构的固有生物相容性和 SPIONs 对外磁场的响应。此外，SPIONs 在类脂支架内的组织可以导致局部增强的 SPIONs 浓度和改善的磁响应，这是克服目前热疗限制的关键。在这里，我们通过小角度 X 射线散射（SAXS）对负载疏水性 SPIONs 的甘油单油酸酯（GMO）/水中间相的热和磁各向异性行为进行了结构研究。我们证明，即使 SPIONs 的含量非常低，也会深刻改变中间相的相行为和热性质，促进立方相向六方相的转变，这类似于施加交变磁场（AMF）时的情况。此外，在六方相中，SPIONs 会在脂质支架内自发地自组装成线性超粒子。这种相行为是在赫夫里希理论的框架内解释的，该理论表明 SPIONs 从粘弹性和结构的角度影响中间相。最后，将这些立方相分散到稳定的磁性胶体颗粒中，这些颗粒保留其液晶内部结构，这是一种有前途的磁响应药物输送系统（DDS）的途径。
