Magnetically induced magnetosome chain (MAGiC): A biogenic magnetic-particle-imaging tracer with high performance and...

Magnetic particle imaging (MPI) enables real-time, sensitive, and quantitative visualization of tracer distribution, augmenting the capability of in vivo imaging technologies. Previous MPI tracer research has predominantly focused on superparamagnetic nanoparticles, whose suboptimal sigmoidal magnetization curves limit their spatial resolution. Here, we introduce the magnetically induced magnetosome chain (MAGiC), a superferromagnetic MPI tracer, demonstrating a 25-fold improvement in resolution in the excitation direction and an order of magnitude improvement in signal intensity compared to the commercial tracer VivoTrax+. Under a gradient field of 4 tesla per meter, the resolution in the excitation direction reached 80 micrometers. Furthermore, MAGiC can be accurately manipulated using magnetic fields, making it an MPI-trackable microrobot. We have elucidated the mechanisms underlying MAGiC's superior performance and validated its effectiveness in vitro and in vivo. As a high-performance MPI tracer and microrobot, MAGiC holds tremendous potential for various applications, such as cell tracking, image-guided drug delivery, and therapeutic interventions.