Magnetically Actuated Degradable Microrobots for Actively Controlled Drug Release and Hyperthermia Therapy

Abstract

Microrobots facilitate targeted therapy due to their small size, minimal invasiveness, and precise wireless control. A degradable hyperthermia microrobot (DHM) with a 3D helical structure is developed, enabling actively controlled drug delivery, release, and hyperthermia therapy. The microrobot is made of poly(ethylene glycol) diacrylate (PEGDA) and pentaerythritol triacrylate (PETA) and contains magnetic Fe3O4 nanoparticles (MNPs) and 5‐fluorouracil (5‐FU). Its locomotion is remotely and precisely controlled by a rotating magnetic field (RMF) generated by an electromagnetic actuation system. Drug‐free DHMs reduce the viability of cancer cells by elevating the temperature under an alternating magnetic field (AMF), a hyperthermic effect. 5‐FU is released from the proposed DHMs in normal‐, high‐burst‐, and constant‐release modes, controlled by the AMF. Finally, actively controlled drug release from the DHMs in normal‐ and high‐burst‐release mode results in a reduction in cell viability. The reduction in cell viability is of greater magnitude in high‐burst‐ than in normal‐release mode. In summary, biodegradable DHMs have potential for actively controlled drug release and hyperthermia therapy.

A magnetically actuated microrobot for targeted neural cell delivery and selective connection of neural networks

“…As microrobots reported previously have shown cell compatibility using human embryonic kidney 293 cells ( 13 ), olfactory receptor neurons ( 14 ), HCT116 cells, hippocampal neural stem cells, and human nasal inferior turbinate–derived mesenchymal stem cells ( 15 ), this microrobot using the same fabrication method could also be successfully applied to primary neurons. To provide enhanced biocompatibility of the microrobot for cell-based analysis applications, the material for magnetic actuation can be replaced with Fe 3 O 4 nanoparticles that have stable cytocompatibility compared to that of Ni ( 30 , 31 ). In contrast to techniques that require the use of a micromanipulator or a micropipette, methods using our proposed microrobot and magnetic control system can be carried out while maintaining the in vitro cell culture environment.…”

Engineering microrobots for targeted cancer therapies from a medical perspective

“…When integrated with gold nanoparticles, irradiation of such microrobots with NIR light causes the gold particles to absorb the NIR light and convert it into local heat via the photothermal effect, which dissolves or restructures the heat-sensitive gelatine/polymers, thereby releasing the drug 52,60,62 . Importantly, the magnetic, acoustic fields and infra-red light irradiation required for the release mechanisms 52,109,164,165 represent approaches feasible for in vivo use in humans. In addition, a mechanical mechanism has been employed in vitro to release drug-loaded spermbots coupled to magnetic tetrapod caps into cancer spheroids, to which they were guided using magnetic fields.…”

“…Cells can be attached to magnetic particles in different geometrical configurations and cell-to-particle ratios to generate magnetically responsive hybrid microrobots of varying speeds 81 , 108 . Furthermore, ferromagnetic particles, like iron oxides, can be internalised by eukaryotic cells, such as red blood cells 85 , 86 , making them amenable to external guidance and acoustic propulsion, or even for hyperthermia-based therapies 109 . Alternatively, magnetotactic bacteria contain naturally synthesised magnetic particles (magnetosomes), allowing them to sense magnetic fields and align their swimming directions along them 110 , 111 .…”

Magnetic Actuation Systems for Miniature Robots: A Review

“…Some continuum end effectors have successfully demonstrated surgical operations, such as atrial fibrillation ablation and percutaneous coronary intervention . Untethered end effectors are good candidates for performing surgery (e.g., thrombolysis, hyperthermia, and cauterization) at some hard‐to‐reach regions …”