Abstract

Recently, we have described a fluorescence-based fiber-optic biosensor for zinc, which uses a metalloenzyme as the sensor transducer. Zinc is bound tightly and specifically to the active site of the enzyme carbonic anhydrase. If we add a fluorescent inhibitor, dansylamide, it binds to the zinc in the active site with concomitant large changes in its fluorescence quantum yield, emission wavelength, and lifetime. In the absence of zinc apocarbonic anhydrase does not bind the inhibitor and one observes the weak, red-shifted, short-lifetime emission of the free dansylamide. These fluorescence changes can be measured through optical fiber and correlated with the zinc concentration, with sup-ppb sensitivity, 50 dB dynamic range, and high selectivity.

© 1995 Optical Society of America