High energy ball milling (HEBM) has been used for the first time to prepare PEGylated magnetite-silica (Fe(3)O(4)-SiO(2)) nanocomposites intended to be used for biological purposes. Surface amine groups were introduced by a silanization reaction involving 3-aminopropyl triethoxysilane (APTS) followed by PEGylation to yield long-term stable and stealth nanocomposites of 200nm in diameter. The efficient coverage by PEG chains was shown by isothermal titration calorimetry (ITC) where PEGylated nanocomposites did not interact with BSA compared to non-PEGylated counterparts which led to a significant change in enthalpy. By cell viability (MTT) assays and cell morphology investigations, it was evidenced that PEGylated Fe(3)O(4)-SiO(2) nanocomposites did not provide any appreciable cytotoxicity on J774 macrophage and MCF-7 breast cancer cell lines. Furthermore, noticeable internalization was evidenced by J774 cells with PEGylated Fe(3)O(4)-SiO(2) nanocomposites in contrast to MCF-7 cells, in good agreement with the respective tendency of each cell line for endocytosis.
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