Quantitative fluorescence spectroscopy of single molecules on surfaces

In recent years, laser induced fluorescence detection and spectroscopy of single molecules (SMD) has seen a tremendous development. Besides fundamental research on individual molecular systems, practical applications of this sensitive detection technique for analytical and diagnostic purposes are becoming more and more important. For a wider applicability of the SMD technique it is desirable to detect not only the presence or absence of a molecule within a given detection volume, but also to be able to quantify this fluorescence absolutely. Modified now cytometry systems for SMD that are ensuring such a quantifiable fluorescence detection of single molecules are already successfully applied for e.g. DNA fragment sizing. In our talk, we present a modified confocal detection set-up for performing SMD on surfaces that aims at a quantified detection of single molecule fluorescence. First experimental results presented and emerging problems are discussed.