Researchers at the University of Ulm in Germany have developed a new and powerful technique to accelerate drug uptake into cancer cells. The method beats slow diffusion-controlled processes – one of the most important limitations in chemotherapy.
Andrei Sommer and colleagues have used laser light with a wavelength of 670 nm to expand and contract the water naturally contained in cancer cells. When the laser is on, the water expands and when it is switched off, the water retracts almost immediately. This process forces the cells to “suck” in drugs from a surrounding solution.
Most existing chemotherapy techniques rely on cells to take up drugs into their interior by diffusion across the bilayer lipid structure of the cell membrane. However, this type of treatment does not always work because cancer cells sometimes become resistant and simply push the drug molecules back out.
Sommer’s team may now have found a way to address this problem. When irradiated with moderately intense (1000 W/m2) red laser light with a wavelength of 670 nm, the density of the nanoscopic water layers naturally confined in biological cells decreases. This instantly expands the volume of the water (since density=mass/volume). The effect is not seen for ordinary, “bulk”, water because it hardly absorbs light of this wavelength.
When the laser is then turned off, the water quickly returns to its original high-density state. To compensate for this increase in density, and subsequent decrease in volume, the cells are forced to absorb water, and any other molecules, from their surroundings.