title: Forbidden light detection from single molecules
abstract: We present a new concept for ultrasensitive detection of surface-generated fluorescence which is made possible by a new optical module. The detection method leads to an enhancement in fluorescence collection efficiency to more than 65% of the total of emitted light, whereas high-aperture microscope objectives are able to collect 44% at best. Moreover, by employing this new optical module, the detection volume can be restricted to approximately 10(-17) L. This allows for an exceptional discrimination of bulk-generated against surface-generated fluorescence, which may be of great value when surface-binding processes are monitored. We demonstrate the performance of the new detection system by detecting single fluorescent molecules and by determining antigen concentrations down to 5 fmol.
authors.affiliation: Physikalisch-Chemisches Institut, Universitat Zurich, Switzerland. thomasr@pci.unizh.ch
authors.initials: T
authors.lastname: Ruckstuhl
authors.initials: J
authors.lastname: Enderlein
authors.initials: S
authors.lastname: Jung
authors.initials: S
authors.lastname: Seeger