ABSTRACT
Single-molecule detection (SMD) represents the ultimate goal in analytical chemistry and is of great
scientific interest in many fields [1-4]. In particular, SMD and activity monitoring in fixed and living
cells have become a fascinating topic of a wide variety of research activities [5-8]. Many of the initial
applications of SMD have been in the area of extremely sensitive imaging and analyte detection [9,10].
Whereas these applications will undoubtedly continue to be important areas, the more intriguing aspect
of SMD lies in the investigation of the dynamics and spectroscopy of single molecules and the
interactions with their molecular environments, by monitoring the chemical and structural changes
of individual molecules [11-13]. Real-time observation of single-molecule activities in living cells is
another important aspect of single-molecule studies [14,15]. These investigations on the single-
molecule level have the potential of offering important perspectives and providing fundamentally new
information about intracellular processes.