Rivera-Llabres Victor G, Fields Zoe A, Good Hayden J, Melnyk Andrii, Rinaldi-Ramos Carlos M
Department of Chemical Engineering, University of Florida, Gainesville, FL 32611, USA.
J. Crayton Pruitt Department of Biomedical Engineering, University of Florida, Gainesville, FL 32611, USA.
J Magn Magn Mater. 2025 Jun 15;622. doi: 10.1016/j.jmmm.2025.172987. Epub 2025 Mar 16.
Magnetic particle imaging (MPI) is a novel imaging modality capable of quantitatively tracking the distribution of magnetic particles in living subjects. While early work on MPI has focused on magnetic nanoparticles as tracers, recent studies have highlighted the potential of magnetic microparticle tracers in MPI, suggesting higher sensitivity on a per particle basis. In this study, we formulated an MPI-tailored, size-tunable microparticle tracer by encapsulating Synomag-D, a commonly used commercial tracer, in an alginate matrix. We evaluated the magnetic properties and MPI performance of Synomag-D pre- and post-encapsulation. Our results show that microfluidics enable the monodisperse formulation of microparticle tracers ranging from 10 to 80 μm in diameter with consistent magnetization behavior. MPI performance evaluation indicated consistent properties across all microparticle tracers and demonstrated that microparticle signal is not dependent on medium viscosity, unlike Synomag-D, suggesting potential advantages in quantification. Dilution experiments revealed detection limits as low as 50 ng of iron for the smallest (~11 μm) microparticles and the potential to detect as few as four of the largest (80 μm) microparticles. Notably, these microparticle tracers exhibit a distinct signal dependence on excitation field amplitude, compared to the free Synomag-D tracer. These microparticle tracers for MPI possess potential applications in cell tracking, perfusion imaging, and multi-contrast MPI.
磁粒子成像（MPI）是一种新型成像方式，能够定量追踪活体中磁性粒子的分布。虽然早期关于MPI的研究主要集中在将磁性纳米粒子作为示踪剂，但最近的研究突出了磁性微粒子示踪剂在MPI中的潜力，表明在单个粒子基础上具有更高的灵敏度。在本研究中，我们通过将常用的商业示踪剂Synomag-D封装在藻酸盐基质中，制备了一种针对MPI定制的、尺寸可调的微粒子示踪剂。我们评估了封装前后Synomag-D的磁性和MPI性能。我们的结果表明，微流控技术能够实现直径为10至80μm的单分散微粒子示踪剂的制备，且具有一致的磁化行为。MPI性能评估表明，所有微粒子示踪剂的性能一致，并证明与Synomag-D不同，微粒子信号不依赖于介质粘度，这表明在定量方面具有潜在优势。稀释实验显示，最小的（约11μm）微粒子的检测限低至50 ng铁，并且能够检测到少至四个最大的（80μm）微粒子。值得注意的是，与游离的Synomag-D示踪剂相比，这些微粒子示踪剂对激发场振幅表现出明显的信号依赖性。这些用于MPI的微粒子示踪剂在细胞追踪、灌注成像和多对比度MPI中具有潜在应用。
