Magnetic iron nanowires track living cells in real time

The technique from a team at KAUST is said to use magnetic core-shell iron nanowires as nontoxic contrast agents, which can be implanted into live cells, lighting up those cells’ location inside a living organism when scanned with magnetic resonance imaging (MRI). The technique could have applications ranging from studying and treating cancer to tracking live-cell medical treatments, including stem cell therapies.

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Jürgen Kosel and his team recently showed that core-shell iron nanowires could selectively kill cancer cells with a combination attack, delivering an anticancer drug into target cells while also puncturing the cell’s membrane and releasing heat into it.

Along with researchers from the CIC biomaGUNE in San Sebastian, Spain, the team has shown that the same type of iron core, iron-oxide shell nanowires, can be used for non-invasive medical imaging. According to KAUST, the nanowires could potentially be used as ‘theranostic’ agents, able to identify, track and then take out target cells. Their results are published in the Journal of Nanobiotechnology.

“Cell labelling and tracking has become an invaluable tool for scientific and clinical applications,” said Aldo Martínez-Banderas, a Ph.D. student in Kosel’s team. “One of the key aspects of cell tracking studies is the sensitivity to detect a small number of cells after implantation, so the strong magnetisation and biocompatibility of our nanowires are advantageous characteristics for MRI tracking.”

The nanowires are said to have performed well as MRI contrast agents, even at very low concentrations, and the magnetic response could be tuned by altering the thickness of the nanowire shell. Furthermore, the nanowire’s biocompatibility permitted long-term tracking of the live cells.

“The nanowires interacted with cells without compromising their survival, functionality or capacity to proliferate,” Martínez-Banderas said in a statement. The labelled cells could be tracked either in cell cultures or once injected into a living animal.

“The strong magnetisation of the nanowires enabled the detection of approximately 10 labelled cells within the brain of a mouse for a period of at least 40 days, which allowed us to trace their exact location and fate in the animal,” Martínez-Banderas said.

“These core-shell nanowires have various additional features, including the ability to control them magnetically to guide them to a particular location, to carry drugs, or be to heated with a laser,” Kosel said. “Combining all of that with the capability of tracking creates a theranostic platform that can open the door for very promising new approaches in nanomedicine.”