contacting polymerase-template complexes in solution with polyethylene glycol PEG) and a salt comprising a cation, thereby providing a first solution;

providing a surface comprising the plurality of nanoscale wells, wherein the plurality of nanoscale wells are bathed in a second solution comprising a buffer;

and

exposing the surface to the first solution, wherein the first solution has a higher density than the second solution, such that the first solution sinks to the bottom of the nanoscale wells and forms a layer underlying the second solution, thereby distributing the polymerase-template complexes into the nanoscale wells.