Skincare Routine: GHK Cu Peptide & Tretinoin Copper Peptide (GHK Cu) 2% Recovery Serum Copper peptides explained what are the differences between copper peptides and GHK CU peptides? What they actually do for the skin in terms of repair and collagen, and what you can and cant mix Retinol vs. GHK Cu Two key ingredients used to address visible signs of ageing. Retinol A popular synthetic molecule that accelerates cellular turnover and skin resurfacing, helping to promote even skin 7% GHK CU ACCELERANT