Schematic of gold label locations in hexagonal and random nanoaggregates. The size of the gold label symbol represents the known steric hindrance of the labeling paradigm, which includes two antibodies as well as the gold particle itself. A, 20 AChRs lie on a hexagonal grid, which can be labeled by at most 8 gold particles because of steric hindrance. B, only 12 AChRs are present in this randomly arrayed nanoaggregate, but the density of gold particles is higher (12 particles per unit area) than in A. For purposes of illustration this figure assumes that every receptor which can be is labeled, however the argument holds at lower binding efficiencies as well.