Metal-Organic Framework Shells Limit the Intracellular Collapse of AC Hysteresis in Magnetite Nanocubes
Year: 2026
Type: preprint
Abstract: Intracellular confinement suppresses the dynamic magnetic losses of nanoparticles after uptake, limiting their efficacy under alternating magnetic fields (AMF). A crystalline metal-organic framework (MOF) shell limits this collapse by enforcing a minimum interparticle spacing that restricts the dipolar coupling imposed by endosomal packing. A conformal UiO-66 shell about 9 nm thick grows directly on poly(ethylene glycol) (PEG)-silane-stabilized Fe3O4 nanocubes at room temperature without N,N- dimethylformamide, giving single-core nanocomposites. AC hysteresis measurements in A549 lung cancer cells show that internalization collapses the loop of PEG-coated nanocubes, which retain only 12% of their aqueous specific loss power (SLP) and 28% of their remanence ratio Mr/Mmax, whereas the MOF-shelled counterparts retain 40% and 47%. Recovering the nanoparticles from the lysed cells reopens the collapsed loops and restores Mr/Mmax to 81% and 89% of the aqueous reference, placing the origin of the loss in the spacing between cores rather than in their degradation. Under safety- compliant AMF, cells containing the nanocomposites lose metabolic activity, reaching 38% of the untreated control by day 7 despite a bulk temperature rise of 1 °C, a response absent in PEG-coated 2 particles at a matched intracellular iron load. Interparticle spacing therefore emerges as a design parameter for intracellular magnetic energy dissipation.
Source: ChemRxiv
Language: English
Subfield: Biomedical Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7221803586