Abstract
Hybrid hydrogels of carboxymethylcellulose (CMC), containing two different amounts of CoFe2O4 magnetic nanoparticles (50% and 70% in relation to the quantity of the polymer) as crosslinkers, were prepared. The hybrid hydrogels were chemically and morphologically characterized and their viscoelastic properties and swelling degrees were analyzed. The hydrogels were tested as controlled drug delivery systems by applying one static and two different alternating magnetic fields. The application of the two alternating magnetic fields (AMF) to the hybrid hydrogels induced a higher release of methylene blue (MB), used as a model drug, than without the application of any magnetic field, especially at low frequency (4 Hz) and high magnetic intensity (0.5 T). In contrast, when the hybrid hydrogels were exposed to a static magnetic field (SMF) the release of MB was slowed down. Furthermore the two different amounts of magnetic nanoparticles induce different responses to the magnetic field. The greater number of nanoparticles in the CMC-NP-70 hydrogel leads to the formation of some NPs clusters limiting the drug release; conversely, the CMC-NP-50 hydrogel, containing a lower amount of nanoparticles, shows a higher release of MB vs. time. In conclusion, we were able to get a potential system for modulation of the drug delivery: the release behaviour of hybrid hydrogels can be modulated by applying alternating and static magnetic fields cyclically. A possible explanation for the release mechanism is about the structural modification of the polymeric chains that occurs when the hybrid hydrogels are exposed to the magnetic fields.
Highlights
Magnetic gels, called ferrogels, consist of polymer networks into which magnetic nanoparticles are embedded
An alternating magnetic field (AMF) induces a higher release of methylene blue (MB) than that occurs in the absence of a MF, especially at low frequency and high magnetic intensity
On the contrary, when the hybrid hydrogels are exposed to static magnetic field (SMF), the release of MB is slowed down
Summary
Called ferrogels, consist of polymer networks into which magnetic nanoparticles are embedded. External magnetic stimuli are mainly used for controlled drug release and represent one of the most common strategies in materials designed for biomedical devices. The literature contains many reports on the development of hydrogels containing magnetic metal oxide NPs. The NPs are incorporated into the polymer matrix by mixing them with a pre-synthesized gel, or by adding them during the gel formation reaction [5]-[7]. The NPs are incorporated into the polymer matrix by mixing them with a pre-synthesized gel, or by adding them during the gel formation reaction [5]-[7] In both cases the NPs are physically embedded within the hydrogel; as a consequence they may be released from the hydrogel or change their position when subjected to a magnetic field [8]. In either event a substantial modification of the properties takes place, which in some cases may render them completely unreliable for applications in the biomedical field
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