title: Developing antifouling biointerfaces based on bioinspired zwitterionic dopamine through pH-modulated assembly.
abstract: The use of synthetic biomaterials as implantable devices typically is accompanied by considerable nonspecific adsorption of proteins, cells, and bacteria. These may eventually induce adverse pathogenic problems in clinical practice, such as thrombosis and biomaterial-associated infection. Thus, an effective surface coating for medical devices has been pursued to repel nonspecific adsorption from surfaces. In this study, we employ an adhesive dopamine molecule conjugated with zwitterionic sulfobetaine moiety (SB-DA), developed based on natural mussels, as a surface ligand for the modification of TiO2. The electrochemical study shows that the SB-DA exhibits fully reversible reduction-oxidation behavior at pH 3, but it is irreversible at pH 8. A contact angle goniometer and X-ray photoelectron spectroscopy were utilized to explore the surface hydration, chemical states, and bonding mechanism of SB-DA. The results indicate that the binding between hydroxyl groups of SB-DA and TiO2 converts from hydrogen bonds to bidentate binding upon the pH transition from pH 3 to 8. In order to examine the antifouling properties of SB-DA thin films, the modified substrates were brought into contact with bovine serum albumin and bacteria solutions. The fouling levels were monitored using a quartz crystal microbalance with dissipation sensor and fluorescence optical microscope. Tests showed that the sample prepared via the pH transition approach provides the best resistance to nonspecific adsorption due to the high coverage and stability of the SB-DA films. These findings support the mechanism of the pH-modulated assembly of SB-DA molecules, and for the first time we demonstrate the antifouling properties of the SB-DA to be comparable with traditional thiol-based zwitterionic self-assemblies. The success of modification with SB-DA opens an avenue for developing a biologically inspired surface chemistry and can have applications over a wide spectrum of bioapplications. The strategy of the pH transition can also be applied to other functional dopamine derivatives.
authors.affiliation: Graduate Institute of Biomedical Engineering and ‡Chemical & Materials Engineering Department, National Central University , Jhong-Li, Taoyuan 320, Taiwan.
authors.forename: Chun-Jen
authors.initials: CJ
authors.lastname: Huang
authors.forename: Lin-Chuan
authors.initials: LC
authors.lastname: Wang
authors.forename: Jing-Jong
authors.initials: JJ
authors.lastname: Shyue
authors.forename: Ying-Chih
authors.initials: YC
authors.lastname: Chang
mesh_terms: D000327:Adsorption; D000818:Animals; D001422:Bacterial Adhesion; D001622:Betaine / Q000031:analogs & derivatives* / Q000737:chemistry; D002417:Cattle; D020099:Coated Materials, Biocompatible / Q000737:chemistry*; D004298:Dopamine / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D011550:Pseudomonas aeruginosa / Q000166:cytology / Q000378:metabolism*; D012710:Serum Albumin, Bovine / Q000737:chemistry; D013212:Staphylococcus epidermidis / Q000166:cytology / Q000378:metabolism*; D013499:Surface Properties; D014025:Titanium
chemical_list: D020099:Coated Materials, Biocompatible; C009495:titanium dioxide; D012710:Serum Albumin, Bovine; D001622:Betaine; C483727:sulfobetaine; D014025:Titanium; D004298:Dopamine