AHK Cu Copper Peptide Hair Growth Study (2007) Plain Language Summary Hairgenetix Copper Peptide Hair Growth Serum AHK Cu & GHK Cu + Licorice Peptide Labz Copper peptides (GHK Cu) have been studied for decades for their role in tissue repair and that same biology applies to hair. Research shows GHK Cu may help strengthen existing hair follicles, reduce GHK Cu vs AHK Cu: Which Copper Peptide Is More Effective? Amazon.com: Copper Peptide Hair Serum with Copper Tripeptide 1 Dual Peptide Scalp Treatment plus Licorice Root Extract : Beauty & Personal Care PDF) The effect of tripeptide copper complex on human hair growth in vitro