Copper Peptide Hair Growth Serum for Hair Loss & Thinning Hair Feline Skinscience Two Ingredients. Real Hair Transformations. How Neurogan Health's GHK Cu Serum Is Changing What Customers Expect From Hair Care GHK Cu Peptide Serum 30 ml, Copper Peptide Serum with Hyaluronic Acid for Tightening, Collagen Boosting Before and after begins with consistency. Our 10% GHK Cu formula is engineered for deep absorption to support scalp health and visible density.