In the directed pharmacotherapy nanoparticle drugs accumulate inside tumour cells – but the occurring processes are not fully explored yet. Magnetic force microscopy is used to subsurface-detect such core-shell structured nanoparticles inside cancer cells. Using multimodal excitation, different physical observables are accessible at the same time, such as topography, magnetic field or Young’s modulus. A frequency modulated control enables high imaging speed and at the same time high resolution imaging. Main goal of this project is to establish the connection between the favoured sites of permeation of the nanoparticles and the mechanical properties of the tumour cells, by providing new, enhanced AFM techniques.