Magnetic-Responsive Microparticles that Switch Shape at 37 °C

Abstract

Shape-memory polymers have seen tremendous research efforts driven by the need for better drug carries and biomedical devices. In contrast to these advancements, fabrication of shape-memory particles which actuate at body temperature remains scarce. We developed a shape-memory microparticle system with dynamically tunable shapes under physiological temperature. Temperature-responsive poly(ε-caprolactone) (PCL) microparticles were successfully prepared by an in situ oil-in-water (o/w) emulsion polymerization technique using linear telechelic and tetra-branched PCL macromonomers. By optimizing the mixing ratios of branched PCL macromonomers, the crystal-amorphous transition temperature was adjusted to the biological relevant temperature. The particles with a disk-like temporal shape were achieved by compression. The shape recovery from the disk to spherical shape was also realized at 37 • C. We also incorporated magnetic nanoparticles within the PCL microparticles, which can be remote-controllable by a magnet, in such a way that they can be actuated and manipulated in a controlled way.

Shape-Memory Nanofiber Meshes with Programmable Cell Orientation

“…By altering topographical cues in a controlled manner, these platforms enable researchers to recapitulate the dynamic nature of physiological conditions like wound healing, organogenesis and tumorigenesis in a dish. We also developed shape-memory microparticles by an in situ oil-in-water emulsion polymerization technique [16]. The particles with a disk-like temporal shape recovered their original spherical shape upon heating.…”

“…While many SMPs have been explored, poly(ε-caprolactone) (PCL)-based SMPs have been utilized as a biomaterial due to their well-characterized biocompatibility [9] and biodegradability [10,11]. Combining SMPs with various fabrication processes has resulted in diverse structures including shape-memory films, foams, particles, surfaces, and fibers [4,[12][13][14][15][16][17][18][19]. Particularly, SMPs in the form of fibers are generating great interest in structural and functional applications owing to their extremely high surface area, porous structure, and filtration/penetration properties [20][21][22][23][24].…”

Shape-memory Nanofiber Meshes with Programmable Cell Orientation

“…Therefore, the manipulation of topographical cues has a strong potential as a strategy for stem cell engineering and regenerative medicine by mimicking changing physiological conditions during would healing, organogenesis, and cancer metastasis. We also developed shape-memory microparticles by an in situ oil-in-water emulsion polymerization technique [15]. The particles with a disk-like temporal shape recovered their original spherical shape upon heating.…”

“…In addition, the development of various fabrication processes for SMPs has resulted in diverse structures. For example, SMPs can be classified as shapememory films, foams, particles, surfaces, and fibers [4,[11][12][13][14][15][16][17]. Particularly, SMPs in the form of fibers are generating great interests in structural and functional applications owing to their extremely high surface area, porous structure, and filtration/penetration properties [18][19][20][21].…”

Surface Structures, Particles, and Fibers of Shape-Memory Polymers at Micro-/Nanoscale

“…Another widely reported manner for demonstrating SMEs at micro-/ nanoscale is to incorporate permanent micro-/nanostructures onto SMP substrates using molding replication as well as to deform them into either flat surface or other structures with different features [29][30][31][32][33][34][35][36][37][38][39][40][41][42][43]. Furthermore, free-standing SMP matrices with all dimensions at microscale are also of increasing interest [44][45][46][47][48].…”