Patent ID: 8664429

Claim:
A hydrolysable linker selected from a compound of formula V, VI, VII, and VIII: wherein: R′ and R″ are each independently a C 1-24 alkylene diradical, wherein from 1-4 of the CH 2 groups within the alkyl chain are optionally independently replaced by O or S atoms, such that each of said O or S atoms is attached only to carbon atoms in the alkyl chain, with the proviso that multiple heteroatoms must be separated from each other and from the diradical chain ends by at least one carbon atom; each a is independently an integer from 0 to 6; each b is independently an integer from 1 to 6; each X is independently: —OC(═O)CH 2 — (inverse glycolic acid moiety), —OC(═O)CH(CH 3 )— (inverse lactic acid moiety), —OC(═O)CH 2 OCH 2 CH 2 — (inverse dioxanone acid moiety), —OC(═O)CH 2 CH 2 CH 2 CH 2 CH 2 — (inverse caprolactone acid moiety), —OC(═O)(CH 2 ) y —, or —OC(═O)CH 2 (OCH 2 CH 2 ) z —; each X 1 is independently: —CH 2 C(═O)O— (glycolic acid moiety), —CH(CH 3 )C(═O)O— (lactic acid moiety), —CH 2 CH 2 OCH 2 C(═O)O— (dioxanone acid moiety), —CH 2 CH 2 CH 2 CH 2 CH 2 C(═O)O— (caprolactone acid moiety), —(CH 2 ) y C(═O)O—, or —(CH 2 CH 2 O) z CH 2 C(═O)O—; each Y is independently: —OCH 2 C(═O)— (inverse glycolic ester moiety), —OCH(CH 3 )C(═O)— (inverse lactic ester moiety), —OCH 2 CH 2 OCH 2 C(═O)— (inverse dioxanone ester moiety), —OCH 2 CH 2 CH 2 CH 2 CH 2 C(═O)— (inverse caprolactone ester moiety), —O(CH 2 ) m C(═O)—, or —O(CH 2 CH 2 O) n OCH 2 C(═O)—; each Y 1 is independently: —C(═O)CH 2 O— (glycolic ester moiety), —C(═O)CH(CH 3 )O— (lactic ester moiety), —C(═O)CH 2 OCH 2 CH 2 O— (dioxanone ester moiety), —C(═O)CH 2 CH 2 CH 2 CH 2 CH 2 O— (caprolactone ester moiety), —C(═O)(CH 2 ) m O—, or —C(═O)CH 2 O(CH 2 CH 2 O) n —; and each m, n, y, and z is independently an integer selected from 2 to 24.