Defy GHK Cu (glycyl L histidyl L lysine) is a naturally occurring copper binding peptide found in human plasma. As levels decline with age, so may its support of the biological processes involved in collagen production, skin GHK Cu as a multifunctional copper peptide: synthesis routes, process engineering and emerging applications Systems Microbiology and Biomanufacturing Springer Nature Link Growth Hormone and Aging Endotext NCBI Bookshelf Oral Liposomal Copper GHK Liposomal GHK Cu Supplement The Human Tripeptide GHKCu in Prevention of Oxidative Stress and Degenerative Conditions of Aging: Implications for Cognitive Health Pickart 2012 Oxidative Medicine and Cellular Longevity Wiley Online Library