With all the remarkable advances in fluorescence imaging, for any given hardware detection limit the question still remains: can one chemically pre-amplify the signal to the detectable level (or alternatively turn the fluorescence off from a detectable level)? We have developed a new methodology for amplified fluorescence quenching based on massive autocatalytic photo-unmasking of a sensitizer, and will discuss its relevance to ultra-sensitive detection of molecular recognition events. In a typical validation experiment (avidin-biotin model) fluorescence cells were loaded with masked sensitizer, the fluorophore, and an amphiphile either with or without the biotinylated lipid, and incubated with a buffer containing the avidin-xanthone conjugate or a blank buffer control. Upon irradiation, 10-fold decrease of emission was detected only in the cell with both avidin and biotin present (1). The controls (2-4) showed little change in emission.In 0.4 �L capillary wells as little as 50 attomoles of avidin was detected.

Photoamplified detection of molecular recognition events: An ultra-sensitive fluorescence turn-off binding assay

242nd National Meeting (2011)

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