Reconfigurable Swarms of Ferromagnetic Colloids for Enhanced Local Hyperthermia

Abstract

Ferromagnetic particles (FMPs) have attracted a large amount of attention for tumor treatment in recent decades in the form of magnetic hyperthermia and thermoablation therapies. Previous research has commonly focused on the improvement of the specific loss power and the increase in the particle concentration to enhance the heating temperature during hyperthermia. Instead of magnetic hyperthermia with passive particles, here a feasible approach of using reconfigurable swarms of ferromagnetic colloidal particles is reported to realize enhanced local hyperthermia. The concentration of the particle swarm can be tuned up to 500% of the original particle concentration via reversible pattern transformation, i.e., shrinking and swelling. The FMP swarms with a controllable pattern size show their potential for directed energy delivery and offer a new strategy for realizing a highly localized heating effect using a low dose of the active FMPs.

Liquid Metal–Based Soft Microfluidics

“…Soft robots, distinguished from the conventional robotics, not only show the robotic features for complete targeted tasks, but also offer intrinsic adaptability and reconfigurability to their www.small-journal.com Small 2020, 16,1903841 surroundings for easier actuation and function. [121][122][123][124] LM, either in the form of droplet or in the form of doping materials, can serve as the key component for the actuation of the softrobotic machines via energy conversion processes that transform various kinds of energy, such as magnetic energy, electric energy, thermal energy, light energy and chemical energy to the kinetic energy. [125] The LM-based robots show their broad applications in the on-demand control and switching of electronic circuits, [126] pumping and mixing of the fluids, [127,128] biomedical therapeutics with targeted delivery capabilities, [129][130][131] and so forth.…”

Engineering microrobots for targeted cancer therapies from a medical perspective

“…Likewise, in hyperthermia therapy target-cells/tissues are exposed to higher than physiological temperatures. Recently, ferromagnetic colloid swarms were steered to cancer cells in vitro using a low-frequency magnetic field, where-under appliance of a high-frequency magnetic field -they induced local heating sufficient to kill the cancer cells 177 . Collectively, it is clear that microrobots hold great promise for oncology, and we envision bright prospects for these tiny machines to efficiently detect and treat a wide range of cancers in the future.…”

“…Notably, the magnetic actuators can be easily scaled-up but then the imaging and feedback control of the untethered microswimmers become more challenging owing to the current spatiotemporal resolution of~150 µm in real time when using cutting-edge ultrasound and optoacoustic imaging systems 28,[172][173][174][175][176] . In this regard, the increased size of individual microrobots over nanomedicines or using microrobot swarms could provide distinct advantages 119,[177][178][179] . However, microrobot size also represents a limitation, as microrobots need to remain small enough to penetrate and reach tumours efficiently as outlined above.…”

Mobile Microrobots for Active Therapeutic Delivery

“…Wang et al. showed controlled swelling and shrinking of magnetic nanoparticles to enhance magnetic hyperthermia heating efficiency of a localized region . The locomotion of a nanoparticle swarm toward cultured cancer cells, and subsequent hyperthermia application using alternating magnetic fields at the shrunk state was further demonstrated.…”