title: Synthesis, characterization and in vitro activity of a surface-attached antimicrobial cationic peptide.
abstract: Infection associated with implanted biomaterials is common and costly and such infections are extremely resistant to antibiotics and host defenses. Consequently, there is a need to develop surfaces which resist bacterial adhesion and colonization. The broad spectrum synthetic cationic peptide melimine has been covalently linked to a surface via two azide linkers, 4-azidobenzoic acid (ABA) or 4-fluoro-3-nitrophenyl azide (FNA), and the resulting surfaces characterized by X-ray photoelectron spectroscopy and contact angle measurements. The quantity of bound peptide was estimated by a modified Bradford assay. The antimicrobial efficacy of the two melimine-modified surfaces against Pseudomonas aeruginosa and Staphylococcus aureus was compared by scanning electron microscopy (SEM) and fluorescence microscopy. Attachment of melimine via ABA gave an approximately 4-fold greater quantity of melimine bound to the surface than attachment via FNA. Surfaces melimine-modified by either attachment strategy showed significantly reduced bacterial adhesion for both strains of bacteria. P. aeruginosa exposed to ABA-melimine and FNA-melimine surfaces showed marked changes in cell morphology when observed by SEM and a reduction of approximately 15-fold (p < 0.001) in the numbers of adherent bacteria compared to controls. For the ABA-melimine surface there was a 33% increase in cells showing damaged membranes (p = 0.0016) while for FNA-melimine there was no significant difference. For S. aureus there were reductions in bacterial adhesion of approximately 40-fold (p < 0.0001) and 5-fold (p = 0.008) for surfaces modified with melimine via ABA or FNA, respectively. There was an increase in cells showing damaged membranes on ABA-melimine surfaces of approximately 87% (p = 0.001) compared to controls, while for FNA-melimine there was no significant difference observed. The data presented in this study show that melimine has excellent potential for development as a broad spectrum antimicrobial coating for biomaterial surfaces. Further, it was observed that the efficacy of antimicrobial activity is related to the method of attachment.
authors.affiliation: University of New South Wales, Sydney, Australia.
authors.forename: Renxun
authors.initials: R
authors.lastname: Chen
authors.forename: Nerida
authors.initials: N
authors.lastname: Cole
authors.forename: Mark D P
authors.initials: MD
authors.lastname: Willcox
authors.forename: Josephine
authors.initials: J
authors.lastname: Park
authors.forename: Riaz
authors.initials: R
authors.lastname: Rasul
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Carter
authors.forename: Naresh
authors.initials: N
authors.lastname: Kumar
mesh_terms: D023181:Antimicrobial Cationic Peptides / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*; D001386:Azides / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism; D001422:Bacterial Adhesion / Q000187:drug effects*; D020099:Coated Materials, Biocompatible / Q000737:chemistry / Q000378:metabolism; D008422:Materials Testing; D015394:Molecular Structure; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000254:growth & development / Q000648:ultrastructure; D013057:Spectrum Analysis / Q000379:methods; D013211:Staphylococcus aureus / Q000166:cytology / Q000187:drug effects / Q000648:ultrastructure; D013499:Surface Properties
chemical_list: D023181:Antimicrobial Cationic Peptides; D001386:Azides; D020099:Coated Materials, Biocompatible; C541912:melimine; C007753:4-fluoro-3-nitrophenyl azide; C087164:4-azidobenzoic acid