The synthesis of a multiblock osteotropic polyrotaxane by copper(I)-catalyzed huisgen 1,3-dipolar cycloaddition.

The design and synthesis of a novel bone-targeting polyrotaxane delivery system that utilizes alendronate (ALN) as targeting moiety is presented in this manuscript. For the introduction of ALN, it is first conjugated to α-cyclodextrin (α-CD) and subsequently threaded onto a short poly(ethylene glycol) (PEG) chain, forming a pseudopolyrotaxane. Using click chemistry, this assembly is copolymerized with bulky monomers that bear imaging and/or therapeutic agent(s) to prevent ALN-functionalized α-CD from dethreading. Overall bone affinity of this novel polymer conjugate can be easily controlled by changing the number of ALN-α-CD incorporated. The osteotropicity of the delivery system was also confirmed in vivo.