Magnetic nanoparticles (MNPs) are effective drug carriers. By using electromagnetic actuated systems, MNPs can be controlled noninvasively in a vascular network for targeted drug delivery (TDD). Although drugs can reach their target location through capturing schemes of MNPs by permanent magnets, drugs delivered to non-target regions can affect healthy tissues and cause undesirable side effects. Real-time monitoring of MNPs can improve the targeting efficiency of TDD systems. In this paper, a two-dimensional (2D) real-time monitoring scheme has been developed for an MNP guidance system. Resovist particles 45 to 65 nm in diameter (5 nm core) can be monitored in real-time (update rate = 2 Hz) in 2D. The proposed 2D monitoring system allows dynamic tracking of MNPs during TDD and renders magnetic particle imaging-based navigation more feasible.

Magnetic nanoparticles (MNPs) exhibiting certain superparamagnetic properties are optimal in terms of drug delivery because they facilitate imaging and targeting of biological interactions at the cellular and molecular levels. In terms of monitoring, magnetic particle imaging (MPI) yields real-time MNPs position and concentration data, and guides MNPs to desired positions if an actuation function is available. Here, we describe a new, user-driven steering scheme for MNPs based on a virtual field free point (FFP). The scheme utilizes our current MPI system, with no need for additional hardware. The scheme facilitates interactive user manipulation with real-time imaging and MNPs actuation within the body. An FFP with four coils was used to model the resultant magnetic force and a virtual FFP to linearize that force with respect to the relative positions of the MNPs and the real FFP. Simulations and experiments confirmed that the direction and magnitude of the forces exerted on MNPs via manipulation of the virtual FFP were controllable. An intuitive guidance system featuring real-time MPI at 2 Hz and user-driven virtual FFP manipulation (via a mouse) was employed to show that MNPs trajectories can be controlled. Our MPI-based navigation platform allows the user to effectively guide MNPs using real-time visual feedback, facilitating targeted drug delivery.

Magnetic nanoparticles (MNPs) are a promising candidate for use as carriers in drug delivery systems. A navigation system with real-time actuation and monitoring of MNPs is inevitably required for more precise targeting and diagnosis. In this paper, we propose a novel electromagnetic navigation system with a coil combined with a soft magnetic core. This system can be used for magnetic particle imaging (MPI) and electromagnetic actuator functions with a higher steering force and enhanced monitoring resolution. A soft magnetic core with coils can increase the magnetic gradient field. However, this also generates harmonic noise, which makes it difficult to acquire MNP monitoring signals with MPI. Therefore, the use of Amplitude Modulation MPI is suggested. Amplitude Modulation MPI uses a low-amplitude excitation field combined with a low-frequency drive field. Using this system, the measured signal becomes less sensitive to the soft magnetic core. Based on the new MPI scheme and the combination of the coil with the magnetic cores, the proposed navigation system can implement one-dimensional (1D) MNP navigation and two-dimensional (2D) MPI. The proposed navigation system can shorten the 1D guidance time by about 25% for MNPs in the size range of 45–60nm and give an improved 2D imaging resolution of 43%, compared with an air-coil structure.

The blood–brain barrier (BBB) hinders drug delivery to the brain. Despite various efforts to develop preprogramed actuation schemes for magnetic drug delivery, the unmodeled aggregation phenomenon limits drug delivery performance. This paper proposes a novel scheme with an aggregation model for a feed-forward magnetic actuation design. A simulation platform for aggregated particle delivery is developed and an actuation scheme is proposed to deliver aggregated magnetic nanoparticles (MNPs) using a discontinuous asymmetrical magnetic actuation. The experimental results with a Y-shaped channel indicated the success of the proposed scheme in steering and disaggregation. The delivery performance of the developed scheme was examined using a realistic, three-dimensional (3D) vessel simulation. Furthermore, the proposed scheme enhanced the transport and uptake of MNPs across the BBB in mice. The scheme presented here facilitates the passage of particles across the BBB to the brain using an electromagnetic actuation scheme.