Abstract: There is described inter alia a device having a surface comprising a layered coating wherein the outer coating layer comprises a plurality of cationic hyperbranched polymer molecules characterized by having (i) a core moiety of molecular weight 14-1,000 Da (ii) a total molecular weight of 1,500 to 1,000,000 Da (iii) a ratio of total molecular weight to core moiety molecular weight of at least 80:1 and (iv) functional end groups, whereby one or more of said functional end groups have an anti-coagulant entity covalently attached thereto.

Abstract: There is described inter alia a medical device having a surface which comprises a coating layer, said coating layer being a biocompatible composition comprising an entity capable of interacting with mammalian blood to prevent coagulation or thrombus formation, which entity is covalently attached to said surface through a link comprising a 1,2,3-triazole.