Detecting nanoscopic objects plays an important role in nanoscience in particular, in the rapidly growing field of nanobiology. The forebear to modern super-resolution microscopy for single molecule investigation, is fluorescence microscopy. Fluorescence as a contrast mechanism, however, brings several restrictions. These include (1) the use of the label itself, which may introduce artifacts to the interpretation, (2) the limited photoemission caused by photobleaching and photoblinking as well as (3) low bandwidth of the emission. Fluorescence-free alternatives are thus highly desirable to overcome these limitations. Optical detection of individual proteins with high bandwidth holds great promise for understanding important biological processes on the nanoscale. In this thesis, we investigate label-free optoplasmonic detection of single proteins and particles in motion. Analysing the data provide information about the hydrodynamic volume of the diffuser and interaction such as binding events. Biological and Soft Matter Physic
