Integrated hyperthermia and magnetic particle imaging system for localized drug-release

Abstract

Magnetic Particle Imaging (MPI) is a fast and sensitive imaging modality, which is well suited as a potential theranostic platform. Especially, a combination of MPI with magnetic hyperthermia heating is an appealing strategy. Here, we aim for a spatially focused and controlled drug release via a temperature-induced burst release mechanism. Compared to hyperthermia for cancer treatment, which typically heats the malicious tissue for apoptosis, triggering drug release requires equally high heating power but with minimal duty cycle, i.e. pulsed heating. We generate sufficient heat around the magnetic nanoparticles to trigger release but without excess heating of the surrounding medium or tissue. MNP-local heating requires fast and precise temperature monitoring and feedback to meet the designated release temperature. Our new integrated system reuses the drive field from MPI for simultaneous magnetic heating and spatial imaging to enable monitoring and treatment. Building on previous work [1-3], we first designed a magnetic particle spectroscopy (MPS) device for initial heating experiments. It operates with a) a fiberoptic temperature probe to obtain SAR/SLP values from calorimetric measurements and b) temperature measurements directly from the MNP magnetization signal, allowing cross-validation of both temperature measurement techniques. It also enables fast direct feedback from the magnetically obtained temperature signal to achieve feedback control in MPS and to target the release temperature of the modified MNPs. We have now successfully implemented ac heating and imaging into a fully integrated prototype MPI system (Fig. 1), which will allow temperature monitoring and control for drug release studies on mice shortly.