Shilin Liu

In situ synthesis of Fe3O4/cellulose microspheres with magnetic-induced protein delivery

Regenerated cellulose microspheres (RCS) were successfully prepared by using the sol-gel transition (SGT) method from cellulose drops in 7 wt% NaOH/12 wt% urea aqueous solution precooled to −12 °C. Subsequently, novel magnetic Fe3O4/cellulose microspheres (MRCS) were fabricated by in situ synthesis of Fe3O4nanoparticles into the cellulose pores of RCS, which were used as the solid template microreactor. Their structure and morphology were analysed using optical photomicrographs, scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. The results indicated that the spherical magnetic Fe3O4nanoparticles were dispersed uniformly and immobilized in the cellulose matrix, and the structure and nature of Fe3O4 were conserved perfectly. The magnetometric measurements revealed that the MRCS exhibited sensitive magnetic-induced delivery, and had extremely small hysteresis loop and low coercivity. Moreover, MRCS displayed excellent adsorption and controlled release capabilities on bovine serum albumin (BSA). The Fe3O4nanoparticles in the cellulose microspheres play an important role in both the creation of the magnetic-induced transference and the improvement of the targeting protein delivery and release. It will be important for applications in the biomaterials field.

Supramolecular structure and properties of high strength regenerated cellulose films.

Water-swollen cellulose films prepared from LiOH/urea solution were uniaxially drawn to investigate the effect of orientation on their supramolecular structure and properties. Their structures and properties were investigated with X-ray diffraction, atomic force microscopy and tensile testing. The results revealed that the drawing process led to substantial reorientation of the cellulose molecular chains, resulting in a significant improvement of their mechanical properties and water-resistance. With an increase of the drawn ratios from 1 to 1.22, the tensile strength of the films at dry and wet states increased from 89 to 213 MPa and 2.9 to 33.9 MPa, respectively. Furthermore, the drawn cellulose films also exhibited good biocompatibility with the capability of supporting cell adhesion and proliferation.

Magnetic Responsive Cellulose Nanocomposites and Their Applications

Magnetically responsive cellulose materials are specific subset of smart materials, in which magnetic nanoparticles are embedded in the polymer matrix, which can adaptively change their physical properties due to an external magnetic field. These kind of materials are expected to exhibit interesting magnetic field-dependent mechanical behavior with a wide range of potential applications, such as fibers and fabrics for protective clothing for military use (Raymond et al., 1994), magnetic filters (Pinchuk et al., 1995), sensors (Epstein & Miller, 1996), information storage, static and low frequency magnetic shielding (Dikeakos et al., 2003) and health care or biomedical products (Wang et al., 2004). In general, magnetic cellulose materials can be prepared with different morphologies, such as films, fibers, microspheres, hydrogels and aerogels, and they respond differently to externally applied magnetic field because of the different natures and structures. The main purpose of the present review is to overview on recent advances in the development of magnetic fieldresponsive cellulose composites with emphasis on the fabrication, properties and possible applications.