Magnetic nanoparticles (MNPs) are used as contrast agents for medical diagnostics during magnetic-resonance imaging of the body. More recently, the ability to control the position-functionalized MNPs is being exploited for hyperthermia – localized heating of cancerous cells induced by application of time modulated magnetic fields – as well as rapid biosensing, drug delivery and cell imaging.

Here, in another application of MNPs, D Sakthi Kumar and colleagues at Toyo University, Saitama, Japan, describe in vitro experiments on the removal of cancerous cells using clusters of aptamer-conjugated MNPs manipulated by external rotating fields.

The researchers used single stranded DNA aptamer (GB-10) conjugated MNPs (˜200 nm carboxylated dextran-coated superparamagnetic particles) to target human glioblastoma and rat normal brain cells.

These MNPs – 'nanosurgeons' – were attached to cancerous cells and rotated by an external magnetic field of 120 Oe at frequencies between 1 and 5 Hz. Importantly, cell death was monitored by monitoring the release of lactate dehydrogenase enzyme (LDH) and intracellular calcium.

The aptamer-MNPs showed a higher affinity towards the glioma target cells than normal rat brain cells, thus highlighting the selectivity of the nanosurgeons. Notably, the nanosurgeons not only enabled the removal of cells but also the aptamer-MNPs also induced cell death.

This research may offer a promising route for non-invasive surgery of cancerous tissues.

The work is reported in Nanotechnology.