GHK Cu as a multifunctional copper peptide: synthesis routes, process engineering and emerging applications Systems Microbiology and Biomanufacturing Springer Nature Link Peptide Therapy in Exeter, NH Exeter Peptide Therapist Mechanisms and Classification of Bioactive Peptides Encyclopedia MDPI GHK Cu may Prevent Oxidative Stress in Skin by Regulating Copper and Modifying Expression of Numerous Antioxidant Genes