Understanding the electrokinetic interaction between nano-particles and a nano-channel is of particular interest in the fast growing field of micro- and nano-fluidics. At relatively high-voltages, wherein concentration-polarization and electro-convective instabilities emerge, the interaction complexity is further increased. It is well established that both colloids and nanochannels/nanopores play an important role in biomolecular detection. Combining these two may suggest a more sensitive detection platform. Depending on the relative dimensions of the nano-channel cross section and colloid size, the latter can either, accumulate at the nano-channel's entrance or pass through it. Our design consists of a nano-slot bounded by two micro-reservoirs, wherein we introduce the dispersed nano-colloids. We drive the fluid and particles into the channel via an electric field using electrophoresis and electro-osmosis. Due to the small dimensions of the nano-slot the presence of these nanoparticles, at its entrance or within the channel, can significantly modify its conductance and the current-voltage (I-V) response curves. The governing physics of the systems are non-linear, thus, at a critical voltage, various electro-kinetic instabilities arise and vortices appear at the entrance to the nano-channel providing further complications. It will be clearly demonstrated, using optical fluorescent microscopy and fast spinning-disk confocal imaging, how these instability induced electro-convection vortices can be used to trap and concentrate colloids at their dynamically formed stagnation points. In parallel, we are performing electrical measurements to characterize the nanoslot conductance and I-V curve.