Molecular Logic Gates Meet Cancer Therapy

Researchers in Turkey are reporting a first attempt to marry molecular computing with photodynamic cancer therapy (J. Am. Chem. Soc. 2009, 131, 48). The idea is to design a molecule that must perform a logic computation before it can help kill cancer cells. In this case, the logic function for the sensitizer molecule (shown) has to recognize two characteristics inherent to cancer cells: high concentrations of H⁺ and Na⁺. When the conditions are satisfied, which in computing terminology is referred to as “AND” logic, the molecule, in the presence of light, generates singlet oxygen (diamagnetic O₂), a reactive oxygen species that destroys cells. The proof-of-principle work was undertaken by Suriye Ozlem of Middle East Technical University and Engin U. Akkaya of Bilkent University, both in Ankara. “As the field of molecular computing grows, it needs applications in areas where conventional silicon computing cannot go—such as inside biological cells,” comments A. Prasanna de Silva, a chemist at Queen’s University of Belfast, in Northern Ireland. The work adds to the growing evidence that “this goal is attainable,” de Silva says, although getting the new molecule across cell membranes may require adding water-soluble groups.