title: Adhesive barnacle peptides exhibit a steric-driven design rule to enhance adhesion between asymmetric surfaces.
abstract: Barnacles exhibit superior underwater adhesion simply through sequencing of the 21 proteinogenic amino acids, without post processing or using special amino acids. Here, we measure and discuss the molecular interaction of two distinct and recurring short peptide sequences (Bp1 and Bp2) inspired from the surface binding 19kDa protein from the barnacle attachment interface. Using self-assembled monolayer (SAMs) of known physical and chemical properties on molecularly smooth gold substrates in 5mM NaCl at pH 7.3, (1) the adsorption mechanisms of the barnacle inspired peptides are explored using quartz crystal microbalance, and (2) adhesion mediating properties are measured using the surface force apparatus. The hydrophobic Bp1 peptide with a cysteine residue adsorbs irreversibly onto Au surfaces due to thiol bond formation, while on hydrophobic CH3SAM surface, the interactions are hydrophobic in nature. Interestingly, Bp2 that contains both hydrophobic and protonated amine units exhibits asymmetric bridging with an exceptionally high adhesion energy up to 100mJ/m2between mica and both gold and CH3SAM. Surprisingly on hydrophilic surfaces such as COOH- or OH-SAMs both peptides fail to show any interactions, implying the necessity of surface charge to promote bridging. Our results provide insights into the molecular aspects of manipulating and utilizing barnacle-mediated peptides to promote or inhibit underwater adhesion.
authors.affiliation: Department of Interface Chemistry and Surface Engineering, Max-Planck Institut für Eisenforschung GmbH, Max-Planck-Straße 1, 40237 Düsseldorf, Germany. Electronic address: raman@mpie.de.
authors.forename: Sangeetha
authors.initials: S
authors.lastname: Raman
authors.affiliation: Department of Materials, Imperial College London, Royal School of Mines, Exhibition Road, London, SW7 2AZ, UK.
authors.forename: Lukas
authors.initials: L
authors.lastname: Malms
authors.affiliation: Department of Interface Chemistry and Surface Engineering, Max-Planck Institut für Eisenforschung GmbH, Max-Planck-Straße 1, 40237 Düsseldorf, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Utzig
authors.affiliation: School of Pharmacy, Université de Montréal, CP6128, succursale Centre-ville, Montreal QC, H3C 3J7, Canada.
authors.forename: Buddha Ratna
authors.initials: BR
authors.lastname: Shrestha
authors.affiliation: Department of Interface Chemistry and Surface Engineering, Max-Planck Institut für Eisenforschung GmbH, Max-Planck-Straße 1, 40237 Düsseldorf, Germany; Institut für Physikalische Chemie, der TU Bergakademie Freiberg, Leipziger Straße 29, 09599 Freiberg, Germany.
authors.forename: Philipp
authors.initials: P
authors.lastname: Stock
authors.affiliation: COMSOL Inc., 10850 Wilshire Boulevard, Suite 800, Los Angeles, CA 90024, USA.
authors.forename: Shankar
authors.initials: S
authors.lastname: Krishnan
authors.affiliation: Department of Interface Chemistry and Surface Engineering, Max-Planck Institut für Eisenforschung GmbH, Max-Planck-Straße 1, 40237 Düsseldorf, Germany; Institut für Physikalische Chemie, der TU Bergakademie Freiberg, Leipziger Straße 29, 09599 Freiberg, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Valtiner
mesh_terms: D000327:Adsorption; D057927:Hydrophobic and Hydrophilic Interactions; D010455:Peptides / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D010455:Peptides
keywords: Adhesion interface; Barnacle cement; Hydrophobic interactions; Non-covalent binding; Peptide bridging; Underwater adhesive