Abstract
Present day biomedical applications, including magnetic biosensing, demand better understanding of the interactions between living systems and magnetic nanoparticles (MNPs). In this work spherical MNPs of maghemite were obtained by a highly productive laser target evaporation technique. XRD analysis confirmed the inverse spinel structure of the MNPs (space group Fd-3m). The ensemble obeyed a lognormal size distribution with the median value 26.8 nm and dispersion 0.362. Stabilized water-based suspensions were fabricated using electrostatic or steric stabilization by the natural polymer chitosan. The encapsulation of the MNPs by chitosan makes them resistant to the unfavorable factors for colloidal stability typically present in physiological conditions such as pH and high ionic force. Controlled amounts of suspensions were used for in vitro experiments with human blood mononuclear leukocytes (HBMLs) in order to study their morphofunctional response. For sake of comparison the results obtained in the present study were analyzed together with our previous results of the study of similar suspensions with human mesenchymal stem cells. Suspensions with and without chitosan enhanced the secretion of cytokines by a 24-h culture of HBMLs compared to a control without MNPs. At a dose of 2.3, the MTD of chitosan promotes the stimulating effect of MNPs on cells. In the dose range of MNPs 10–1000 MTD, chitosan “inhibits” cellular secretory activity compared to MNPs without chitosan. Both suspensions did not caused cell death by necrosis, hence, the secretion of cytokines is due to the enhancement of the functional activity of HBMLs. Increased accumulation of MNP with chitosan in the cell fraction at 100 MTD for 24 h exposure, may be due to fixation of chitosan on the outer membrane of HBMLs. The discussed results can be used for an addressed design of cell delivery/removal incorporating multiple activities because of cell capability to avoid phagocytosis by immune cells. They are also promising for the field of biosensor development for the detection of magnetic labels.
Highlights
IntroductionMagnetic ferrofluids ferrofluids (FFs)(FFs) have have been been attracting attracting increasing increasing interest interest for for technological technological and and Magnetic biomedical applications in recent years
The list of proposed applications has extended rapidly, extended with rapidly, with delivery uses such as drug delivery carriers, contrast media for magnetic counting usescounting such as drug carriers, contrast media for magnetic resonance imaging, resonance imaging, magnetic labels for magnetic biosensing, thermal ablation and hyperthermia, magnetic labels for magnetic biosensing, thermal ablation and hyperthermia, thermal activation for thermal activation for [4,5,6,7]
Thermomagnetic zero field cooled/field cooled (ZFC-FC) curves were obtained for the field of 100 Oe (5–300 K temperature range) for air-dry magnetic nanoparticles nanoparticles (MNPs) and MNPs dried from ferrofluids
Summary
(FFs) have have been been attracting attracting increasing increasing interest interest for for technological technological and and Magnetic biomedical applications in recent years. Chitosan is widely tested as an efficient biocompatible stabilizer in the suspensions of nanoparticles of different chemical origin designed for biomedical applications [16] The presence of both hydroxyl and amine residues in chitosan monomer unit enhance specific interaction of chitosan macromolecules with the surface of metal oxide MNPs and provide the stability of suspensions at low polymer concentration [17,18]. In our recent works [19,20] we had introduced a route to overcome this limitation and provide the stabilization of iron oxide MNPs by chitosan in phosphate buffer saline (PBS, pH = 6.3), which is widely used in biomedical and bioengineering studies This approach is based on the well-known feature of colloidal suspensions that their stability depends on the composition and on the prior history of their preparation. We present our study on the fabrication, thorough characterization and biocompatibility of the suspensions of iron oxide MNPs electrostatically or sterically stabilized by chitosan tested for the case of human blood mononuclear leukocytes
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