Therapeutic and imaging compositions and uses thereof

A polyrotaxane having the general formula:

• or a salt thereof,
• wherein:
• n is an integer from 1 to 30;
• C and C′ are the same or different and represent endcapping groups of the formula:
• wherein
• L1 is a (C1-C6)hydrocarbylene group,
• G1 is a substituted or unsubstituted (C1-C6)hydrocarbylene group, interrupted by 0 to 5 groups chosen from —O—, —NH—, and —S—,
• G2 is substituted or unsubstituted (C1-C6)hydrocarbylene-(C6-C50)hydrocarbyl group, interrupted by 0 to 5 groups chosen from —O—, —NH—, and —S—, wherein the (C6-C50)hydrocarbyl group is sterically bulky, and
• t is an integer from 2 to 5;
• B represents a polymer chain of the formula:
• wherein
• each R5 is independently a substituted or unsubstituted (C1-C20)hydrocarbyl group,
• d is an integer from about 100 to about 800, and q is an integer from about 100 to about 800;
• and
• A represents the macrocyclic host molecule of the general formula:
• wherein
• each Z is O,
• each R1 is independently hydrogen or a substituted or unsubstituted (C1-C20)hydrocarbyl group, interrupted by 0 to 5 groups chosen from —O—,
• —NH—, and —S—;
• x is an integer from 1 to 3;
• and
• R2 is substituted or unsubstituted (C1-C20)hydrocarbyl group, interrupted by 0 to 5 groups chosen from —O—, —NH—, and —S—;
• with the proviso that at least one R1 is a substituted or unsubstituted (C1-C20)hydrocarbyl group, interrupted by 0 to 5 groups chosen from —O—, —NH—, and —S—.