Hydroxyapatite-targeting poly (ethylene glycol) and related polymers

A hydroxyapatite-targeting, biologically active polymeric structure comprising a linear or branched water-soluble and non-peptidic polymer backbone having at least two termini, a first terminus being covalently bonded to a hydroxyapatite-targeting moiety and a second terminus covalently bonded to a biologically active agent through a linker, wherein at least one of the polymer backbone and the linker comprise a hydrolytically or enzymatically degradable linkage.

A method of preparing an isolatable hydroxyapatite-targeting polymeric structure, comprising:

• providing a polymeric structure comprising a linear or branched water-soluble and non-peptidic polymer backbone having at least two termini, a first terminus covalently bonded to a first protected chemically reactive group and a second terminus covalently bonded to a second chemically reactive group selected from the group consisting of active carbonates and active esters;
• and
• reacting the second chemically reactive group with a hydroxyapatite-targeting moiety to form a hydroxyapatite-targeting polymeric structure.

A method of preparing a hydroxyapatite-targeting, biologically active polymeric structure, comprising:

• providing a polymeric structure comprising a linear or branched water-soluble and non-peptidic polymer backbone having at least two terimin, a first terminus being covalently bonded to a hydroxyapatite-targeting moiety and a second terminus covalently bonded to a chemically reactive group, wherein the chemically reactive group is protected or unprotected;
• and
• reacting the chemically reactive group with a biologically active agent such that the biologically active agent is attached to the second terminus of the polymeric structure to form a hydroxyapatite-targeting, biologically active polymeric structure.

A method of utilizing a bone surface in an organism as a reservoir for a releasable biologically active agent, comprising:

• providing a hydroxyapatite-targeting, biologically active polymeric structure comprising a linear or branched water-soluble and non-peptidic polymer backbone having at least two termini, a first terminus being covalently bonded to a hydroxyapatite-targeting moiety and a second terminus covalently bonded to a biologically active agent through a linker, wherein at least one of the polymer backbone and the linker comprise a hydrolytically or enzymatically degradable linkage;
• and
• administering a therapeutically effective amount of the polymeric structure to a bone-containing organism such that at least a portion of the polymeric structure is bonded to a bone surface by the hydroxyapatite-targeting moiety.