New nanomachines can drill into, destroy cancer cells

Scientists have developed motorised molecules driven by light that can drill holes in the membranes of cancerous cells, an advance that may pave the way for new therapies to treat the deadly disease.
Researchers showed how rotors in single-molecule nanomachines can be activated by ultraviolet light to spin at two to three million rotations per second and open membranes in cells.
Test motors designed to target prostate cancer cells broke through their membranes from outside and killed them within one to three minutes of activation, said Robert Pal at Durham University in the UK.
The cells showed increased blebbing - bubbling of the membrane. This effect can be seen, in the image above, as bulges from the small dark spots on a human prostate cell (stained green), which is under attack by motorised molecules.

The nanomachines could prove to be effective against a range of cancers including those that resist currently available treatments.
"We are moving towards realising our ambition to be able to use light-activated nanomachines to target cancer cells such as those in breast tumours and skin melanomas, including those that are resistant to existing chemotherapy," said Pal.

"Once developed, this approach could provide a potential step change in non-invasive cancer treatment and greatly improve survival rates and patient welfare globally," he said.
The research used motors based on work by Nobel laureate Bernard Feringa, who won the prize for chemistry in 2016.

The motor itself is a paddle-like chain of atoms that can be prompted to move in a single direction when supplied with energy.
Properly mounted as part of the cell-targeting molecule, the motor can be made to home in on specific cells and spin when activated by a light source.
Researchers created motor-bearing molecules in several sizes as well as peptide-carrying nanomachines designed to target and kill specific cells.
They then tested the molecules on synthetic replicas of cell membranes.
Tests on live cells, including human prostate cancer cells, showed that without an ultraviolet trigger, motors could locate specific cells of interest but stayed on the targeted cells' surface and were unable to drill into the cells.

When triggered, however, the motors rapidly drilled through the membranes.
Researchers expect the rotors may eventually be activated by other means, such as two-photon absorption, near-infrared light or radio frequencies, which would pave the way toward the establishment of novel, easy and cost-effective photodynamic therapy.