CELLS absorb chemotherapy drugs more readily if they are zapped with red light. The finding could help produce more effective cancer treatments.

Most cancer chemotherapy relies on cells absorbing drugs by diffusion across the cell membrane. This does not always work, because some cells simply push the drug molecules back out using a natural pump mechanism.

To overcome this problem, Andrei Sommer at the University of Ulm in Germany and colleagues exposed cells to pulsed red laser light. Light of this wavelength decreases water density and pushes water out of the cell. When the laser is switched off, the water returns to its high-density state, forcing the cell to “suck in” water and any other molecules, including drugs, from its surroundings.

The researchers tested their technique by applying the light for 1 minute to human cervical cancer cells surrounded with common anti-cancer drugs such as epigallocatechin gallate (EGCG). This short period of light exposure was sufficient to kill off 70 per cent of cancer cells surrounded by EGCG, compared with 31 per cent of cells not exposed to light (Journal of Controlled Release, DOI: 10.1016/j.jconrel.2010.10.010).