Abstract : Several ways exist to handle and detect single molecules. The oldest one is to measure the ionic current going through a single nanometric pore. This thesis uses this technique. The discussion is built in two main parts. Firstly, the use of a single track-etched nanopore is aimed to reproduce experiments already made in the litterature with other kinds of pores. Some phenomena, like rectification for example, were observed, whereas others, like translocation, were not. Secondly, the investigation of electric conductance noise proves the existence of a phenomenon which has not been pointed out before in the litterature yet. Indeed, this noise can be ascribed neither to fluctuations of the pore geometry nor to the pore wall charges, but rather to a cooperative effect on ions motion in confined geometry.