Department of Experimental Molecular Imaging (ExMI), Helmholtz Institute for Biomedical Engineering, Medical Faculty, RWTH Aachen University, Aachen 52074, Germany.
Biomaterials. 2011 Sep;32(26):6155-63. doi: 10.1016/j.biomaterials.2011.05.019. Epub 2011 May 31.
Magnetic resonance (MR) and ultrasound (US) imaging are widely used diagnostic modalities for various experimental and clinical applications. In this study, iron oxide nanoparticle-embedded polymeric microbubbles were designed as multi-modal contrast agents for hybrid MR-US imaging. These magnetic nano-in-micro imaging probes were prepared via a one-pot emulsion polymerization to form poly(butyl cyanoacrylate) microbubbles, along with the oil-in-water (O/W) encapsulation of iron oxide nanoparticles in the bubble shell. The nano-in-micro embedding strategy was validated using NMR and electron microscopy. These hybrid imaging agents exhibited strong contrast in US and an increased transversal relaxation rate in MR. Moreover, a significant increase in longitudinal and transversal relaxivities was observed after US-induced bubble destruction, which demonstrated triggerable MR imaging properties. Proof-of-principle in vivo experiments confirmed that these nanoparticle-embedded microbubble composites are suitable contrast agents for both MR and US imaging. In summary, these magnetic nano-in-micro hybrid materials are highly interesting systems for bimodal MR-US imaging, and their enhanced relaxivities upon US-induced destruction recommend them as potential vehicles for MR-guided US-mediated drug and gene delivery.
磁共振（MR）和超声（US）成像是各种实验和临床应用中广泛使用的诊断方式。在这项研究中，氧化铁纳米粒子嵌入的聚合物微泡被设计为用于混合 MR-US 成像的多模态对比剂。这些磁性纳米-微成像探针是通过一锅乳液聚合制备的，形成聚丁基氰基丙烯酸酯微泡，并在泡壳中进行油包水（O/W）封装氧化铁纳米粒子。纳米-微嵌入策略使用 NMR 和电子显微镜进行了验证。这些混合成像剂在 US 中表现出强烈的对比，并且在 MR 中横向弛豫率增加。此外，在 US 诱导的泡破坏后观察到纵向和横向弛豫率显著增加，这表明具有触发式 MR 成像特性。体内实验的初步结果证实，这些纳米粒子嵌入的微泡复合材料是适用于 MR 和 US 成像的对比剂。总之，这些磁性纳米-微混合材料是双模态 MR-US 成像的极具吸引力的系统，并且在 US 诱导破坏后增强的弛豫率推荐它们作为 MR 引导的 US 介导的药物和基因递送的潜在载体。
