Recent efforts in development of multifunctional nanoscale materials, and in particular nanoparticles (NPs) for use as drugs delivery, targeted therapeutic and imaging agent have made significant progress [1, 2]. Magnetic NPs and in particular cobalt ferrites (CoFe2O4), offer some attractive possibilities in biomedicine as drug delivery carriers, hyperthermia treatments in cancer therapy and magnetic resonance imaging (MRI) contrast enhancement [3, 4].. However, along with developing their vast implementation there is a growing concern about the health hazards related to the possible toxic effects of the NPs. The lacking information about the NPs impact on environment and on human health as well as data on risk assessment requires reliable methodology for control and prediction. Among the promising detection methods is the synchrotron radiation x-ray fluorescence (SRXRF) that has already demonstrated its potential in bio-medical research exploring e.g. neurodegenerative disorders [5, 6]. Extending the application of SRXRF using soft X-rays [7] has also provided access to light elements natural constituents of the living matter. In this work we report SRXRF investigation of the distribution and chemistry of CoFe2O4nanoparticles on balb3T3 mouse fibroblast cells exposed to NPs concentrations ranging between 40 and 1000 uM for 24h. The SRXRF maps and micro-spot spectra indicate that, for concentrations below 500 uM, the NPs are localized in the perinuclear region, whilst at higher concentration they penetrate also in the nuclei, where the Fe/Co ratio indicates that the cells are not able to counteract the toxic effect of NPs chemical components (i.e. cobalt). A co-localization of P, Ca and Fe at high concentration has also been observed indicating intracellular sequestration mechanisms as a response or in an attempt to reduce the nanoparticles toxic effects. Preliminary PIXE (Proton Induced Ion Emission) measurements support the XRF results indicating that at 250uM the Fe and Co are localized around the nucleus whilst Ca, P, S, K, Zn and Na are uniformly distributed in the cell.

 

References

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[7] R. Alberti et al., X-ray Spectrometry 38 (2009), 205-209