Synthesis of a temperature-responsive multimodal motion microrobot capable of precise navigation for targeted controllable drug release

doi:10.12122/j.issn.1673-4254.2025.08.20

Abstract

Abstract:

Objective To synthesize a temperature-responsive multimodal motion microrobot (MMMR) using temperature and magnetic field-assisted microfluidic droplet technology to achieve targeted drug delivery and controlled drug release. Methods Microfluidic droplet technology was utilized to synthesize the MMMR by mixing gelatin with magnetic microparticles. The microrobot possessed a magnetic anisotropy structure to allow its navigation and targeted drug release by controlling the temperature field and magnetic field. In the experiment, the MMMR was controlled to move in a wide range along a preset path by rotating a uniform magnetic field, and the local circular motion was driven by a planar rotating gradient magnetic field of different frequencies. The MMMR was loaded with simulated drugs, which were released in response to laser heating. Results Driven by a rotating magnetic field, the MMMR achieved linear motion following a predefined path. The planar gradient rotating magnetic field controlled circular motion of the MMMR with an adjustable radius, utilizing the centrifugal force generated by rotation. The drug-loaded MMMR successfully reached the target location under magnetic guidance, where the gelatin matrix was melted using laser heating for accurate drug release, after which the remaining magnetic particles were removed using magnetic field. Conclusion The MMMR possesses multimodal motion capabilities to enable precise navigation along a predefined path and dynamic regulation of drug release within the target area, thus having great potential for a wide range of biomedical applications.

Key words: drug delivery, microrobot, magnetic anisotropy, multimodal motion, microfluidic synthesis

Xuhui ZHAO, Mengran LIU, Xi CHEN, Jing HUANG, Yuan LIU, Haifeng XU. Synthesis of a temperature-responsive multimodal motion microrobot capable of precise navigation for targeted controllable drug release[J]. Journal of Southern Medical University, 2025, 45(8): 1758-1767.

Figures/Tables 6

Fig.1 Principle of temperature-responsive multimodal motion microrobot (MMMR) synthesis and drug release. A: Principles of MMMR synthesis. B: Design and appearance of the synthesis device. C: Drug delivery principle of the MMMR capable of precise navigation and controlled drug release.

Fig.2 Multimodal motion control of the MMMR. A: Magnetic control platform and control interface for linear motion control. B: Schematic diagram of linear motion of the MMMR. C: Schematic illustration of the rotating gradient magnetic field and a photograph of the device. D: Schematic diagram of circular motion of MMMR.

Fig.3 Synthesis of the MMMR. A: Synthesis device of MMMR. B: Randomly dispersed particles in magnetic hydrogel beads. C: Assembled particles in magnetic hydrogel beads (Scale bar=150 μm). D: Size control principle of the hydrogel beads. E: Magnetic hydrogel beads with a diameter of 70 μm. F: Magnetic hydrogel beads with a diameter of 500 μm. G: Relationship between oil pressure and the diameter of beads. H: Relationship between magnetic hydrogel pressure and the generation frequency of beads.

Fig.4 Local circular motion and targeted drug delivery experiments with MMMR. A: Local circular motion principle. B: Movement of the MMMR under a rotating gradient magnetic field (Scale bar=10 mm). C: Relationship between speed of rotation and the radius of orbit. D: Relationship between magnetic field frequency and the linear motion speed of the MMMR. E: Test of the MMMR for targeted drug delivery (Scale bar=5 mm). F: Test of the MMMR for drug release and magnetic particle removal.

Fig.5 Synthesis quality and biocompatibility of the MMMR. A: Fluorescence images of the MMMR co-cultured with cells for 6 h. B: Fluorescence images of the MMMR co-cultured with cells for 12 h. C: Scanning electron microscopy of the MMMR. D: Blood compatibility test of the MMMR. E: MMMR images under microscope (Scale bar=1 mm). F: Coefficient of variation (CV) analysis of the MMMR. G: Hysteresis loop test of the 3 MMMRs.

Fig.6 Experiments of the MMMR for drug delivery in isolated organs. A: Test of the MMMR for targeted drug delivery and laser heating release on the surface of the small intestine (Scale bar=5 mm). B: X-ray image of the MMMR (Scale bar=5 mm).

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