Copper Peptide Hair Growth Serum (GHK Cu & AHK Cu) GHK Cu vs NAD+: Which Longevity Peptide Should You Take or Stack? PDF) The effect of tripeptide copper complex on human hair growth in vitro GHK Cu (Copper Peptide) has emerged as one of the most promising regenerative peptides for hair restoration due to its ability to stimulate follicular activity, improve scalp circulation, reduce inflammation, and prolong the