Firefly luciferase, luciferin, 1-(3,4-dimethoxy-6-nitrophenyl) elthyl ATP and 1-(2-nitrophenyl) ethyl acetic acid were immobilised in an agarose gel matrix. By illuminating the gel with 350 nm light through a mask, a positive bioluminescent pattern was written on to the gel by releasing ATP in the illuminated areas. The gel was then illuminated with a brpadbnand UV light through a second mask to release acetic acid, lowering the local pH and deactivating the enzyme. This produced a negative image of the second mask superimposed on the positive image of the first mask.
The system represents a two-wavelength switch in which one wavelength of light activates the enzyme while a second deactivates it. This demonstrates the feasibility of using biological molecules as logic element in future devices.