By use of spin-resolved POLARIS experiments it is planned to analyze the spin coupling between magnetic nanoparticles in 5 different types of particle clusters. With particle sizes in the range of 8 - 40 nm these particles can be regarded in all cases as single-domain particles and are aggregated to small clusters. The cluster size (~ 30 nm to a few µm) and type of arrangement (e.g. close packed clusters or linear chains) varies between the samples. Within the clusters the individual particle moments (single-domains) are strongly interacting due to dipole-dipole interactions/stray fields.It is expected that within the 5 samples the spin coupling due to dipolar interactions significantly varies, which can be verified by the proposed POLARIS experiments. The results would be of high interest regarding a wide range of potential biomedical applications of these nanoparticle clusters, such as hyperthermia, magnetic drug targeting or magnetic biosensing.