In situ measurements of magnetic nanoparticles after placenta perfusion

Nanoparticles (NP) present promising tools for medical applications. Nevertheless, the current lack of knowledge about their potential toxicity hinders further applications. Besides the local interactions, especially the spatial distribution and the kinetics are key factors in toxicity assessments. However, the investigation of the spatial and temporal distribution is hampered by missing in-situ particle detection and quantification technologies. An interesting model for the study of the particle distribution at a biological barrier represents the placenta perfusion experiment. It allows the ex-vivo investigation of the permeability of the placenta for materials of interest. We introduce an approach based on a magnetic system for an in situ measurement of the concentration of magnetic NPs in such an experiment. Therefore a previously off-line utilized magnetic readout device (sensitivity of a few μAm2) was used for long term measurements of magnetic NP of 100-150 nm size range in a closed circuit of a placenta perfusion. It represents a semiquantitative approach. The behaviour of particles in the placenta and in the measurement system was studied, as well as the influence of particle surface modifications. The results suggest a transfer of a low amount of particles from the maternal to the fetal blood circuit.