Apparatus for use in performing a diagnostic assay of an analyte, the apparatus comprising a base that has been structured using laser processing so as to provide at least one patterned surface by melting and resolidification of the base, wherein the patterned surface is characterized by structures ranging in scale from 10 to 2000 nanometers and further wherein the pattern is stochastic in all three spatial dimensions; and a metal applied to the at least one patterned surface so as to provide at least one metalized patterned surface.