The present disclosure relates to the field of molecular biology and more specifically to microarrays and methods, including methods for modifying immobilized capture primers comprising: a) contacting a substrate comprising a plurality of immobilized capture primers with a plurality of template nucleic acids under conditions sufficient for hybridization to produce one or more immobilized template nucleic acids, and b) extending one or more immobilized capture primers to produce one or more immobilized extension products complementary to the one or more template nucleic acid.