Therapeutic and imaging compositions and uses thereof

A polyrotaxane comprising a poloxamer core and at least one cyclodextrin comprising a nuclide chelating moiety, wherein the polyrotaxane has 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 and G2, together, form a radical having the formula:
• wherein each L2 is independently a bond or acyl;
• each G3 is a substituted or unsubstituted (C6-C50)hydrocarbyl group, interrupted by 0 to 5 groups chosen from —O—, —NH—, and —S—, wherein the (C6-C50)hydrocarbyl group;
• and each s is independently an integer from 1 to 5;
• and
• t is an integer from 2 to 5;
• B is a polyalkylene oxide polymer;
• and
• A is a cyclodextrin.