Nanoparticles have been used in research and medicine for decades and not until recently, has the community been able to truly accelerate their utility for monitoring functional events within the body and as therapeutic tools. Nanoparticles as contrast agents and tracers are simple and safe option for imaging workflows. With the introduction of magnetic particle imaging, ordinary particle tracers have the ability to expose therapeutic workflows in cell treatments, monitoring inflammation and vascular perfusion in a quantitative format without radiation.
Nanotechnology in Cancer and Immunology
Gold Nanoparticles in Cell Cytosol. Gold nanoparticles are nontoxic, can carry a variety of therapeutic and diagnostic agents ,and are small enough to reach targets in the body inaccessible to other delivery systems. This dark-field image shows the delivery of gold nanoparticles (yellow dots) into the cytosol of a cancer cell. Source: National Cancer Institute, M.D. Anderson Cancer Center, Rice University.
Vaccine-Based Immunotherapy from Novel Nanoparticle Systems. Particle-based vaccines developed for cancer therapy carry molecules that stimulate immune cells and cancer antigens (proteins) that direct the immune response. This scanning electron microscope image shows dendritic cells (pseudo-colored in green) interacted with T cells (pseudo-colored in pink). The dendritic cells internalize the particles, process the antigens, and present peptides to T cells to direct immune responses. Source: National Cancer Institute. Creator: Victor Segura Ibarra and Rita Serda, Ph.D.
Magnetic Particle Imaging (MPI) uses superparamagnetic iron oxide (SPIOs) particles. SPIOs are biocompatible, safe and have been utilized in clinical settings in the past as contrast agent for MRI.
Iron oxide particles can be tailored to the specific experiments, to allow for stronger contrast in a static magnetic field, or rapid reaction to varying gradients. Another application area is the ability to transform penetrating radio-frequency excitation into heat, opening the door to localized and graded hyperthermia. This can be used for thermo-ablation, localized heat actuation or generation of a local immune response.
Current exciting research areas include:
- Refining and creating new tracers
- Multi-modal tracer development for BLI and MRI co-registration
- Theragnostic tracers
The insurgence of new application-specific particles and nanocarriers, is one of the pillars of MPI. This is based on years of research in particle contrast imaging agents for MRI, their pharmacokinetics along with ligand binding chemistry used in PET and optical imaging that translates into the growing application fields of MPI.
Particle Characterization Tools for MPI
Translating or purposely designing a new nanoparticle for your applications for MPI is facilitated through particle relaxometry. From spherical mono-dispersed iron oxide cores to complex multi-domain geometric configurations, relaxometry provides you with the information necessary to understand your nanoparticle. The RELAX™ module for the MOMENTUM MPI system can help researchers predict the behavior like sensitivity or resolution before starting precious in vivo experiments.
References:
- Butte et al. Superparamagnetic Iron Oxides as MPI Tracers: A Primer and Review of Early Applications. Adv Drug Deliv Rev. 2019;138: 293-301.
- Song et al. Janus Iron Oxides @ Semiconducting Polymer Nanoparticle Tracer for Cell Tracking by Magnetic Particle Imaging. Nano Lett. 2018;18(1): 182-189.
- Song et al. A Magneto-Optical Nanoplatform for Multimodality Imaging of Tumors in Mice. ACS Nano. 2019;13(7): 7750-7758.
- Zhu et al. Quantitative Drug Release Monitoring in Tumors of Living Subjects by Magnetic Particle Imaging Nanocomposite. Nano Lett. 2019;19(10): 6725-6733.
- Kuan et al. Vector Acquisition for Improved Isotropic Resolution in Magnetic Particle Imaging. Transactions on Medical Imaging. 2017.