Fe 3 O 4 /poly (e-caprolactone)-polyurethane (PCLU) shape memory nanocomposites were prepared by an in situ polymerization method. The thermal properties, magnetic properties, and shape memory properties of the nanocomposites were investigated systematically. The results showed that the Fe 3 O 4 nanoparticles were homogeneously dispersed in the PCLU matrix, which ensured good shape memory properties of nanocomposites in both hot water and an alternating magnetic field (f ¼ 45 kHz, H ¼ 29.7 kA m À1 /36.7 kA m À1 ). The nanocomposites started to recover near 40 C, which is slightly higher than body temperature. Thus, they would not change their deformed shape during the implanting process into the human body. Considering potential clinical applications, 45 C was chosen as shape recovery temperature which is slightly higher than 37 C, and the nanocomposites had high shape recovery rate at this temperature. With increasing content of Fe 3 O 4 nanoparticles, the shape memory properties of the nanocomposites in an alternating magnetic field increased and the best recovery rate reached 97%, which proves that this kind of nanocomposites might be used as potential magnetic sensitive shape memory materials for biomedical applications.

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In this paper, we have developed a simple, facile, and efficient approach to synthesize bifunctional Fe3O4/Au hybrid nanostructure using l-cysteine as a linker. The morphology, composition, crystallinity, and magnetism of the as-prepared nanocomposites were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), powder X-ray diffraction (XRD), and superconducting quantum interference device (SQUID). The results indicated that the spherical composite particles showed a monodispersity and supermagnetism. The surface of the composite spheres contained plentiful Au nanoparticles (NPs) smaller than 10 nm. And the absorption peak of the composite spheres could be conveniently tuned over a broad spectral range spanning from the visible to the near-infrared (NIR) by simply controlling the diameter of Fe3O4. This novel bifunctional hybrid nanostructure will open up an exciting opportunity in biomedical applications.

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