Patterning With Fluorophores

In a new approach to patterning surfaces on micrometer scales, researchers have linked inert fluorescent molecules to an insulating surface by using copper-catalyzed "click" chemistry (J. Am. Chem. Soc., DOI: 10.1021/ja078183d). Sung-Yu Ku and Ken-Tsung Wong of National Taiwan University along with Allen J. Bard of the University of Texas, Austin, used a scanning electrochemical microscope's ultramicroelectrode to reduce a Cu(II) complex to Cu(I). The Cu(I), in turn, catalyzed the cycloaddition of the fluorophore benzothiodiazole acetylene to an azido-terminated siloxane monolayer on a glass substrate (shown, R = benzothiodiazole moiety). A 100-μm-diameter electrode produced fluorescent spots about 300 μm in diameter on the substrate. The features of the fluorescent patterns should be controllable by adjusting the size of the electrode tip and the distance from the tip to the substrate, the authors say.