Biochemical changes of macrophages and U87MG cells occurring as a result of the exposure to iron oxide nanoparticles detected with the Raman microspectroscopy

•Raman microscopy and multivariate methods allows to follow biochemical anomalies in cells after the exposure to IONPs.•IONPs influence biochemical composition of macrophages and U87MG cells but not HEK293T cells.•IONPs with 10 nm core diminished the accumulation of biomolecules in cells only when were administered at a larger dose.•The spectra of some cells exposed to the action of IONPs show the presence of Raman bands in the range 1700–2400 cm−1.•Small IONPs may be internalized into U87MG cells what points at their diagnostic/therapeutic potential in case of gliomas.