Cross-linkers for hydrogels, hydrogels including these cross-linkers and applications thereof

The present invention relates to novel cross-linkers for hydrogels, in particular for hyaluronan hydrogels, corresponding hydrogels including said cross-linkers and various applications thereof. The cross linker of the invention is a bi- or multifunctional cross-linker comprising or consisting of an aromatic or heteroaromatic ring system with 3-6 C atoms which is coupled via functional groups on at least 2 ring positions with at least 2 terminal groups capable to form a covalent bond with thiol or amino groups, in particular with thiol groups in a thiol-en reaction. The cross-linker may be charged or uncharged. In a specific embodiment, the terminal groups are coupled to carboxy groups of the aromatic or heteroaromatic ring system via an ester or amide bond. More specifically, the cross-linker of the invention is a derivative of pyridine-3,5-dicarboxylic acid or a corresponding pyridinium salt thereof wherein 2 terminal groups are coupled to the carboxy groups of the pyridine or pyridinium core via an ester or amide bond. In a preferred embodiment, the cross-linker if N3,N5-bis(2-acrylamidoethyl) pyridine-3,5-dicarboxamide or a 3,5-bis((2-acryl-amidoethyl) carbamoyl)-1-methylpyridin-1-ium-halogenide.