Amino lipids and methods for the delivery of nucleic acids

An amino lipid having the following structure (II):

• or salts thereof, wherein
• R1 and R2 are either the same or different and independently optionally substituted C12-C24 alkyl, optionally substituted C12-C24 alkenyl, optionally substituted C12-C24 alkynyl, or optionally substituted C12-C24 acyl;
• R3 and R4 are either the same or different and independently optionally substituted C1-C6 alkyl, optionally substituted C1C6 alkenyl, or optionally substituted C1C6 alkynyl, or R3 and R4 may join to form an optionally substituted heterocyclic ring of 4 to 6 carbon atoms and 1 or 2 heteroatoms chosen from nitrogen and oxygen;
• R5 is either absent or is hydrogen or C1C6 alkyl to provide a quaternary amine;
• m, n, and p are either the same or different and independently either 0 or 1 with the proviso that m, n, and p are not simultaneously 0;
• Y and Z are either the same or different and independently O, S, or NH.