Copper peptide preparations, where the metal is part of the molecule rather than an additive alongside it.GHK-Cu is a coordination complex: copper(II) held by a three-residue peptide. That distinction is not pedantry — essentially the entire research literature concerns the complex rather than the free peptide, and free peptide plus a copper salt is not the same material. The blue colour is a property of the intact complex, which makes it a more informative visual cue than most peptides give you.Our GHK-Cu guide covers the chemistry and the handling consequences. All products are sold for laboratory research use only.