Patent ID: 7491538

Claim:
A complex for delivering a nucleic acid to a cell, comprising: said nucleic acid modified at the N7 positions of guanines in the nucleic acid with a plurality of alkylating agents selected from the list consisting of: a) compounds having a group containing three or more positively charge groups and a net positive charge linked to a mustard or three-membered ring nucleic acid reactive group; b) compounds having three mustard nucleic acid reactive groups; and wherein reaction with the nucleic acid crosslinks the nucleic acid; and, c) compounds having a sulfhydryl or disulfide group and a mustard or three-membered ring nucleic acid reactive group wherein the sulfhydryl or disulfide groups are oxidized or exchanged to form disulfide bonds between pairs of compounds attached to the nucleic acid, thereby crosslinking the nucleic acid; wherein said modification compacts, reduces the volume of, or reduces the hydrodynamic radius of the nucleic acid when compared to the unmodified nucleic acid.