Fig. (4) Examples for synthesis process related quality differences of silica-coated ferromagnetic nanoparticles (NPs). A: Macroscopic and microscopic (inset) appearance of a homogenous, freshly prepared  suspension of well dispersed NPs, suitable for coating of isolated glomeruli. The NPs were synthetized strictly  following the protocol described in the Material and Methods section and suspended in coating buffer (10 mg/ml  CB). B, C: Inhomogenous suspensions of NPs with large NP-aggregates and clumps, unsuitable for podocyte  isolation (compare to Fig. 7E). During the synthesis of the NPs shown in B, the ammonia solution was injected  too slowly into the aqueous FeSO₄ and FeCl₃ solution, whereas in C, FeSO₄ and FeCl₃ were not completely  dissolved, prior to injection of the ammonia solution. Bars = 1 cm. Bars in insets = 50 μm.