Conjugate of the formula P(OSO3 - M +) n (L-G-E) m, wherein P is a polyol macromolecule in which a number n of hydroxyl groups is substituted by sulfate groups OSO3 - M +, n being a number > 10, M is a cationic inorganic or organic counter ion to the anionic sulfate group, E is a therapeutic or diagnostic effector molecule, L is a linker or spacer between P and E, G is a reactive group for the covalent attachment between L and E, and m is a number of 1 - 100, wherein the sulfated polyol macromolecule is a sulfated polyglycerol that is covalently conjugated to a therapeutic or diagnostic effector molecule E and wherein the sulfated polyglycerol comprises: a. a polymeric polyglycerol, composed of repeated units of glycerol with the formula (RO-CH2)2CH-OR on a multifunctional starter molecule, which is a polyhydroxy compound having 1 to 1,000 OH groups, wherein R is H or further glycerol units, the branching degree of the polyol macromolecule core being > 60% to 67% and its average molecular weight being 2,000 to 20,000 g/mol, and b. the substitution of a plurality of OH groups of the glycerol units with -OSO 3 H or-OSO 3 - M + with a number n of -OSO 3 H or -OSO 3 - M + groups above 10, and a degree of sulfation X of 30 to 100%, and c. the resulting average molecular weight of the sulfated polyglycerol being 4,000 to 50,000 g/mol, and d. a linker unit L carrying a functional group G, attached to at least one of the OH groups up to maximal 100 - X % of the OH groups, with the functional groups being able to be conjugated with an additional therapeutic or diagnostic effector molecule, wherein X is the degree of sulfation, and e. a diagnostic and/or therapeutic effector molecule E, covalently attached to one up to the maximal possible number of said functional groups, the diagnostic effector molecule being selected from the group of fluorescent dyes or chelators for radioactive or paramagnetic metals, and the therapeutic effector molecules being selected from the group of cytostatics, anti-angiogenetic drugs, photosensitizers, siRNAs. a. a polymeric polyglycerol, composed of repeated units of glycerol with the formula (RO-CH2)2CH-OR on a multifunctional starter molecule, which is a polyhydroxy compound having 1 to 1,000 OH groups, wherein R is H or further glycerol units, the branching degree of the polyol macromolecule core being > 60% to 67% and its average molecular weight being 2,000 to 20,000 g/mol, and b. the substitution of a plurality of OH groups of the glycerol units with -OSO 3 H or-OSO 3 - M + with a number n of -OSO 3 H or -OSO 3 - M + groups above 10, and a degree of sulfation X of 30 to 100%, and c. the resulting average molecular weight of the sulfated polyglycerol being 4,000 to 50,000 g/mol, and d. a linker unit L carrying a functional group G, attached to at least one of the OH groups up to maximal 100 - X % of the OH groups, with the functional groups being able to be conjugated with an additional therapeutic or diagnostic effector molecule, wherein X is the degree of sulfation, and e. a diagnostic and/or therapeutic effector molecule E, covalently attached to one up to the maximal possible number of said functional groups, the diagnostic effector molecule being selected from the group of fluorescent dyes or chelators for radioactive or paramagnetic metals, and the therapeutic effector molecules being selected from the group of cytostatics, anti-angiogenetic drugs, photosensitizers, siRNAs.