Interactions between Magnetic Nanowires and Living Cells : Uptake, Toxicity and Degradation

TL;DR

This study investigates how magnetic nanowires are taken up, tolerated, and broken down by mouse fibroblast cells, showing they are internalized without immediate toxicity and can be degraded, indicating potential for biomedical applications.

Contribution

It demonstrates cellular internalization, lack of short-term toxicity, and cellular degradation of magnetic nanowires, highlighting their suitability for biomedical use.

Findings

Nanowires are internalized within cells in membrane-bound compartments or dispersed in cytosol.

The wires do not cause acute toxicity within 100 hours of incubation.

Cells can degrade the nanowires into smaller aggregates within days.

Abstract

We report on the uptake, toxicity and degradation of magnetic nanowires by NIH/3T3 mouse fibroblasts. Magnetic nanowires of diameters 200 nm and lengths comprised between 1 {\mu}m and 40 {\mu}m are fabricated by controlled assembly of iron oxide ({\gamma}-Fe2O3) nanoparticles. Using optical and electron microscopy, we show that after 24 h incubation the wires are internalized by the cells and located either in membrane-bound compartments or dispersed in the cytosol. Using fluorescence microscopy, the membrane-bound compartments were identified as late endosomal/lysosomal endosomes labeled with lysosomal associated membrane protein (Lamp1). Toxicity assays evaluating the mitochondrial activity, cell proliferation and production of reactive oxygen species show that the wires do not display acute short-term (< 100 h) toxicity towards the cells. Interestingly, the cells are able to degrade the wires and to transform them into smaller aggregates, even in short time periods (days). This degradation is likely to occur as a consequence of the internal structure of the wires, which is that of a non-covalently bound aggregate. We anticipate that this degradation should prevent long-term asbestos-like toxicity effects related to high aspect ratio morphologies and that these wires represent a promising class of nanomaterials for cell manipulation and microrheology.