Metal-Organic Framework Shells Limit the Intracellular Collapse of AC Hysteresis in Magnetite Nanocubes
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.
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BibTeX
@misc{kopp2026metalorganic,
title = {{Metal-Organic Framework Shells Limit the Intracellular Collapse of AC Hysteresis in Magnetite Nanocubes}},
author = {Josef Kopp and Giulia Zampini and Samuel Funes-Hernando and Manuel Ceballos and Sajid Fazal and José Manuel Vila-Fungueiriño and Beatriz Pelaz and Pablo del Pino},
howpublished = {ChemRxiv},
year = {2026},
month = oct,
doi = {10.26434/chemrxiv.15010448/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15010448/v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - Metal-Organic Framework Shells Limit the Intracellular Collapse of AC Hysteresis in Magnetite Nanocubes
AU - Josef Kopp
AU - Giulia Zampini
AU - Samuel Funes-Hernando
AU - Manuel Ceballos
AU - Sajid Fazal
AU - José Manuel Vila-Fungueiriño
AU - Beatriz Pelaz
AU - Pablo del Pino
PY - 2026
DA - 2026/10/14
PB - ChemRxiv
DO - 10.26434/chemrxiv.15010448/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15010448/v1
AB - 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.
ER -