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Abstract: Magnetic sponge-like hydrogels (ferrosponges) were fabricated by using an in-situ synthesis of magnetic nanoparticles (MNPs) in the presence of various concentrations of gelatin. The resulting ferrosponges show an interconnected nanopore structure which serves as a reservoir to accommodate therapeutic drugs and the nanoporous networks demonstrate magnetic sensitive behavior under the application of magnetic field. The ferrosponges showed high swelling ratios, together with excellent elasticity and hydrophilicity, allow them to response rapidly to an external magnetic stimulation for fast and repeatable swelling-deswelling (or expansion–contractile) operations. The ferrosponges with lower gelatin concentration exhibited good performance on magnetification. Furthermore, drug release from the ferrosponges is relatively magnetic-sensitive and is dominated by its magnetism and associated interaction between the magnetic nanoparticle and the gelatin matrix under an external magnetic field. Higher MNPs concentration in the ferrosponges exhibited higher degree of magnetic sensitive which is due to stronger interparticle forces. By taking these peculiar magnetic sensitive behaviors of the ferrosponges, a novel drug delivery system can be designed for medical uses. [Copyright &y& Elsevier]

Abstract: A PVA-based magnetic-sensitive hydrogel (ferrogel) was fabricated by physical cross-linking through a freezing–thawing method. The influence of the constituting components, i.e., Fe3O4 and PVA, on the magnetic-sensitive behavior of the ferrogels was systematically investigated in terms of permeability coefficient (P), partition coefficient (H), space restriction and magnetization. The results show that, the P value in these ferrogels decreases and displays a magnetic sensitivity when it is subjected to magnetic field (MF), which is correlated with the change of H value. In addition, it was found that although the factor of space restriction or magnetization exerts opposite effect on resulting magnetic-sensitive behavior, the superior magnetic-sensitive behavior was observed for the ferrogels with an optimal composition of 17–34% Fe3O4 and 10–12.5% PVA, and can be well correlated with theoretical calculation from the critical parameters of available free volume per nanoparticle (V free) and magnetization. A map of magnetic-sensitive behavior was constructed, where a region with relatively stable and highly stimuli-responsive behavior in terms of the concentration of Fe3O4 was observed, however, below or above the “saturation” region (17–34% Fe3O4), a reduction in the magnetic-sensitive behavior was detected. The resulting ferrogels can be engineered with a precise control of the opening and closure of pore configuration, which allows a burst release or no-release action of therapeutically active agent to be controlled externally and magnetically. This suggests that this type of ferrogel can be considered as a class of novel magnetically-tunable drug delivery system. [Copyright &y& Elsevier]

Abstract: The magnetic hydrogels were successfully fabricated by chemically cross-linking of gelatin hydrogels and Fe3O4 nanoparticles (ca. 40–60nm) through genipin (GP) as cross-linking agent. The cross-sectional SEM observation demonstrates that the Fe3O4 nanoparticles were fairly uniformly distributed in the gelatin matrix. Moreover, in vitro release data reveal that drug release profile of the resulting hydrogels is controllable by switching on or off mode of a given magnetic field. While applying magnetic fields to the magnetic hydrogels, the release rate of vitamin B12 of the hydrogels was considerably decreased as compared with those when the field was turned off, suggesting a close configuration of the hydrogels as a result of the aggregation of Fe3O4 nanoparticles. Based on this on-&-off mechanism, the smart magnetic hydrogels based on the gelatin-ferrite hybrid composites can be potentially developed for application in novel drug delivery systems. [Copyright &y& Elsevier]