Maghemite nanoparticles protected with a shell of Simanek (melamine) dendrons of three different generations were achieved via multiple-step syntheses. The resulting nanoclusters exhibited switchable solubility in various solvents and were examined as soluble matrices for supporting magnetically recoverable homogeneous Pd catalysts in organic solvents and as potential MRI contrast agents in aqueous media. Successful promotion of Suzuki reactions and the observation of generation-dependent dendritic effects with strong MR relaxivities suggest broad application possibilities for dendron-maghemite nanoparticles across many fields.

[Structure: see text] As a result of the unique surface structure of nanospheres, Asp and His residues supported on a 12 nm maghemite nanoparticle worked collaboratively as a biomimetic nanocatalyst for hydrolyzing paraoxon (phosphoester) and 4-nitrophenyl acetate (carboxylic ester) in Milli-Q water (pH 7.0) at 37 degrees C, without employing extremes of pH or heavy metals. Our nanocatalyst could be facilely recovered via magnetic concentration. The isolated catalyst exhibited long-term stability, showing no significant loss of its catalytic activity for repeated uses after 3 months.

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