The peptide and metallocene-peptide bioconjugates R-Arg-Arg-Phe-NH2, R-Phe-Arg-Phe-NH2 where R = H, Fe(Cp)(C5H4-CO), CO(Cp)(C5H4-CO)(+) and R'-Gly-Trp-Arg-Arg-Phe-NH2, R'-Trp-Arg-Arg-Phe-NH2, where R' = n-C5H11 CO, Fe(CPK5H4- CO), CO(CP)(C5H4-CO)(+), and Arg = L-arginine, Gly = L-glycine, Phe = L-phenylalanine, Trp = L-tryptophan were prepared by solid phase peptide synthesis (SPPS). The compounds were purified by RP-HPLC and characterized by ESI-MS and NMR spectroscopy. Antibacterial properties of the compounds were determined by minimum inhibitory concentration (MIC) tests against Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus. (c) 2005 Elsevier B.V. All rights reserved.