Abstract: This invention relates to protein fibrils, to methods and kits of producing those protein fibrils comprising a plurality of first peptide monomer units arranged in a first strand and a plurality of second peptide monomer units arranged in a second strand in which said first and second strands form an overlapping staggered heterodimer coiled coil structure, and wherein the amino acid residues on the exposed surface of said first and second strands enable said protein fibril to interact with another protein fibril in a plurality of non-parallel orientations. This invention also relates to bundles of protein fibrils and matrices, in particular, hydrogels produced using those protein fibrils.