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.