Copper Peptide Hair Growth Serum AHK Cu & GHK Cu + Licorice Peptide Labz Duo: Copper Complex Natural Topical HPIHair AHK CU + GHK Cu Hair Serum Pro 4800mg Hair Growth Neurogan GHK Cu Topical Cream GHK Cu for Hair Growth? It Works But Only If You Do It Right. Everyone's talking about GHK Cu, but here's the catch most serums never make it past your scalp barrier. 2% GHK CU Copper Peptide Serum for Hair Growth and Scalp Care