GHK Cu Hair Growth GHK Cu Copper Peptide for Hair Loss: Results, Mechanism, and What to Expect Small molecules. Powerful results. Experience Peptide Power with Hairgenetix's advanced Copper Peptide Hair Growth Serum, formulated with 10% GHK Cu and 5% AHK Cu to support hair health at the follicle level. Helps Copper Peptide Hair Growth Serum for Hair Loss & Thinning Hair Feline Skinscience GHK Cu vs AHK Cu: Which Copper Peptide Is More Effective?