Morphology-controlled magnetite nanoclusters via polyethyleneimine-mediated solvothermal process

A facile one-pot synthesis of polyethyleneimine (PEI)-functionalized magnetic nanoclusters (MNPs) through the solvothermal method was reported for various applications. The morphology of the MNPs can be systematically tuned from loose flower-like to porous nanoclusters by controlling the pH of the PEI stabilizer. At low pH, the intense electrostatic repulsion according to the large amount of protonated amine groups of PEI would play a key role on self-assembly process to generate the loose nanostructure. Due to the presence of amine functional groups on the surface, these nanoclusters provide high degree of dispersibility in water and abundant anchoring groups for further attachment of biomolecules. Magnetization study of the MNPs indicated that they had saturated magnetization upto 80 emu g−1.

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► The morphology of PEI-coated magnetic nanoclusters can be manipulated by altering pH of PEI.
► The plausible formation process is discussed based on the experimental results.
► The nanoclusters can be easily manipulated by external magnetic fields.
► The free amine groups located on the nanocluster surface allow stability and surface modification.