Degradable hyaluronic acid hydrogels

A conjugate comprising crosslinked hyaluronic acid strands to which a plurality of drug moieties are covalently and reversibly conjugated, wherein the conjugate comprises a plurality of connected units selected from the group consisting of

• wherein
• an unmarked dashed line indicates a point of attachment to an adjacent unit at a dashed line marked with # or to a hydrogen;
• a dashed line marked with # indicates a point of attachment to an adjacent unit at an unmarked dashed line or to a hydroxyl;
• a dashed line marked with § indicates a point of connection between at least two units Z3 via a moiety —CL-;
• each —CL- comprises at least one degradable bond between the two carbon atoms marked with the * connected by a moiety —CL- and each —CL- is independently selected from the group consisting of formula (C-i), (C-ii), and (D-i),
• wherein
• dashed lines indicate attachment to a moiety —X0F— of a unit Z3;
• -D, -L1-, -L2-, -L3-, -L4-, —SP—, —X0A—, —X0B—, —X0C—, —X0D—, —X0E—XF, —Ra1 and —Ra2 are used as in claim 1;
• wherein
• all units Z1 present in the conjugate may be the same or different;
• all units Z2 present in the conjugate may be the same or different;
• all units Z3 present in the conjugate may be the same or different;
• the number of Z1 units ranges from 1% to 98% of the total number of units present in the conjugate;
• the number of Z2 units ranges from 0% to 98% of the total number of units present in the conjugate;
• the number of Z3 units ranges from 1% to 97% of the total number of units present in the conjugate, provided that at least one unit Z3 is present per strand which is connected to at least one unit Z3 on a different hyaluronic acid strand.