Engineering Nitroxide Functional Surfaces Using Bioinspired Adhesion.
Hendrik WoehlkJan SteinkoenigChristiane LangLukas MichalekVanessa TrouilletPeter KrollaAnja S GoldmannLeonie BarnerJames P BlincoShivshankar R ManeKathryn E Fairfull-SmithPublished in: Langmuir : the ACS journal of surfaces and colloids (2018)
We pioneer a versatile surface modification strategy based on mussel-inspired oxidative catecholamine polymerization for the design of nitroxide-containing thin polymer films. A 3,4-dihydroxy-l-phenylalanine (l-DOPA) monomer equipped with a 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-derived oxidation-labile hydroxylamine functional group is employed as a universal coating agent to generate polymer scaffolds with persistent radical character. Various types of materials including silicon, titanium, ceramic alumina, and inert poly(tetrafluoroethylene) (PTFE) were successfully coated with poly(DOPA-TEMPO) thin films in a one-step dip-coating procedure under aerobic, slightly alkaline (pH 8.5) conditions. Steadily growing polymer films (∼1.1 nm h-1) were monitored by ellipsometry, and their thicknesses were critically compared with those obtained from atomic force microscopic cross-sectional profiles. The heterogeneous composition of surface-adherent nitroxide scaffolds examined by X-ray photoelectron spectroscopy was correlated to that examined by in-solution polymer analysis via high-resolution electrospray ionization mass spectrometry, revealing oligomeric structures with up to six repeating units, mainly composed of covalently linked dihydroxyindole along the polymer backbone. Critically, the reversible redox-active character of the nitroxide-containing polymer scaffolds was investigated by cyclic voltammetric measurements, revealing a convenient and facile access route to electrochemically active nitroxide polymer coatings with potential application in electronic devices such as organic radical batteries.
Keyphrases
- high resolution
- mass spectrometry
- cross sectional
- single molecule
- escherichia coli
- photodynamic therapy
- pseudomonas aeruginosa
- biofilm formation
- cystic fibrosis
- solid state
- minimally invasive
- quantum dots
- tandem mass spectrometry
- capillary electrophoresis
- carbon nanotubes
- highly efficient
- high performance liquid chromatography
- atomic force microscopy