Typical experiment vs. in-cell like conditions in magnetic hyperthermia: Effects of media viscosity and agglomeration

•Magnetic nanoparticles heating power alters when medium changes from liquid to gel.•Inductive determination of magnetic cycles in both media shows clear differences.•Agglomerated particles in gel present ordered structure with well defined spacing.•SAR values for the same particles are larger in gel matrix than in liquid suspension.•Results at different field parameters show a lower resonant frequency in the gel.