A polyrotaxane comprising the general formula: or salts thereof, wherein: each m and n is, independently, an integer from 0 to 30, with the proviso that m + m' + n + n' is from about 4 to about 30; C and C' are the same or different and represent end capping groups of the formula: wherein each L 2 is independently a bond or (C 1 -C 6 )acyl; each G 3 is a substituted or unsubstituted (C 6 -C 50 )hydrocarbyl group, interrupted by 0 to 5 groups chosen from -O-,-NH-, and -S-, wherein the (C 6 -C 50 )hydrocarbyl group is sterically bulky; and each s is independently an integer from 1 to 6; B represents: to which the endcapping groups are covalently attached to B via a (C 1 -C 6 )hydrocarbylene group or B represents carbohydrates, polypeptides, polycarbonate, polyamide, or polyester polymers; wherein R 5 is methyl; d is an integer from about 1 to about 800; and q is an integer from about 6 to about 800; and A and A' each represents the macrocyclic host molecule of the general formula (I): wherein: A and A' are different; x is an integer from 0 to 8; Z is O or NH; each R 1 and R 2 is, independently, hydrogen, a substituted or unsubstituted (C 1 -C 6 )hydrocarbyl group or a group of the formula (IIIc): wherein y is an integer from 0 to 10; p is an integer from 1 to 10; X 2 represents (C 1 -C 6 )acyl, a short-chain polypeptide, a short-chain carbohydrate, a polyester or a polyamide; X 3 and X 4 are each, independently, -O-, -NH-, a carbamyl group, a heterocyclyl group, a disulfide (-S-S-), amide or ester; and R 4 is a reporter group, with the proviso that at least one R 2 group is a group of the formula (IIIc). each m and n is, independently, an integer from 0 to 30, with the proviso that m + m' + n + n' is from about 4 to about 30; C and C' are the same or different and represent end capping groups of the formula: wherein each L 2 is independently a bond or (C 1 -C 6 )acyl; each G 3 is a substituted or unsubstituted (C 6 -C 50 )hydrocarbyl group, interrupted by 0 to 5 groups chosen from -O-,-NH-, and -S-, wherein the (C 6 -C 50 )hydrocarbyl group is sterically bulky; and each s is independently an integer from 1 to 6; B represents: to which the endcapping groups are covalently attached to B via a (C 1 -C 6 )hydrocarbylene group or B represents carbohydrates, polypeptides, polycarbonate, polyamide, or polyester polymers; wherein R 5 is methyl; d is an integer from about 1 to about 800; and q is an integer from about 6 to about 800; and A and A' each represents the macrocyclic host molecule of the general formula (I): wherein: A and A' are different; x is an integer from 0 to 8; Z is O or NH; each R 1 and R 2 is, independently, hydrogen, a substituted or unsubstituted (C 1 -C 6 )hydrocarbyl group or a group of the formula (IIIc): wherein y is an integer from 0 to 10; p is an integer from 1 to 10; X 2 represents (C 1 -C 6 )acyl, a short-chain polypeptide, a short-chain carbohydrate, a polyester or a polyamide; X 3 and X 4 are each, independently, -O-, -NH-, a carbamyl group, a heterocyclyl group, a disulfide (-S-S-), amide or ester; and R 4 is a reporter group, with the proviso that at least one R 2 group is a group of the formula (IIIc). A and A' are different; x is an integer from 0 to 8; Z is O or NH; each R 1 and R 2 is, independently, hydrogen, a substituted or unsubstituted (C 1 -C 6 )hydrocarbyl group or a group of the formula (IIIc): wherein y is an integer from 0 to 10; p is an integer from 1 to 10; X 2 represents (C 1 -C 6 )acyl, a short-chain polypeptide, a short-chain carbohydrate, a polyester or a polyamide; X 3 and X 4 are each, independently, -O-, -NH-, a carbamyl group, a heterocyclyl group, a disulfide (-S-S-), amide or ester; and R 4 is a reporter group, with the proviso that at least one R 2 group is a group of the formula (IIIc). <EOS>