title: Detailed Study of BSA Adsorption on Micro- and Nanocrystalline Diamond/β-SiC Composite Gradient Films by Time-Resolved Fluorescence Microscopy.
abstract: The adsorption of bovine serum albumin (BSA) on micro- and nanocrystalline diamond/β-SiC composite films synthesized using the hot filament chemical vapor deposition (HFCVD) technique has been investigated by confocal fluorescence lifetime imaging microscopy. BSA labeled with fluorescein isothiocyanate (FITC) was employed as a probe. The BSAFITCconjugate was found to preferentially adsorb on both O-/OH-terminated microcrystalline and nanocrystalline diamond compared to the OH-terminated β-SiC, resulting in an increasing amount of BSA adsorbed to the gradient surfaces with an increasing diamond/β-SiC ratio. The different strength of adsorption (>30 times for diamond with a grain size of 570 nm) coincides with different surface energy parameters and differing conformational changes upon adsorption. Fluorescence data of the adsorbed BSAFITCon the gradient film with different diamond coverage show a four-exponential decay with decay times of 3.71, 2.54, 0.66, and 0.13 ns for a grain size of 570 nm. The different decay times are attributed to the fluorescence of thiourea fluorescein residuals of linked FITC distributed in BSA with different dye-dye and dye-surface distances. The longest decay time was found to correlate linearly with the diamond grain size. The fluorescence of BSAFITCundergoes external dynamic fluorescence quenching on the diamond surface by H- and/or sp2-defects and/or by amorphous carbon or graphite phases. An acceleration of the internal fluorescence concentration quenching in BSAFITCbecause of structural changes of albumin due to adsorption, is concluded to be a secondary contributor. These results suggest that the micro- and nanocrystalline diamond/β-SiC composite gradient films can be utilized to spatially control protein adsorption and diamond crystallite size, which facilitates systematic studies at these interesting (bio)interfaces.
authors.affiliation: Physical Chemistry I, ‡Research Center of Micro and Nanochemistry and Engineering (Cμ), and §Institute of Materials Engineering, University of Siegen , 57076 Siegen, Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Handschuh-Wang
authors.affiliation: Physical Chemistry I, ‡Research Center of Micro and Nanochemistry and Engineering (Cμ), and §Institute of Materials Engineering, University of Siegen , 57076 Siegen, Germany.
authors.forename: Tao
authors.initials: T
authors.lastname: Wang
authors.affiliation: Physical Chemistry I, ‡Research Center of Micro and Nanochemistry and Engineering (Cμ), and §Institute of Materials Engineering, University of Siegen , 57076 Siegen, Germany.
authors.forename: Sergey I
authors.initials: SI
authors.lastname: Druzhinin
authors.affiliation: Physical Chemistry I, ‡Research Center of Micro and Nanochemistry and Engineering (Cμ), and §Institute of Materials Engineering, University of Siegen , 57076 Siegen, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Wesner
authors.affiliation: Physical Chemistry I, ‡Research Center of Micro and Nanochemistry and Engineering (Cμ), and §Institute of Materials Engineering, University of Siegen , 57076 Siegen, Germany.
authors.forename: Xin
authors.initials: X
authors.lastname: Jiang
authors.affiliation: Physical Chemistry I, ‡Research Center of Micro and Nanochemistry and Engineering (Cμ), and §Institute of Materials Engineering, University of Siegen , 57076 Siegen, Germany.
authors.forename: Holger
authors.identifier: 0000-0002-5836-5569
authors.initials: H
authors.lastname: Schönherr
mesh_terms: D000327:Adsorption; D000818:Animals; D017554:Carbon Compounds, Inorganic / Q000737:chemistry*; D002417:Cattle; D018130:Diamond / Q000737:chemistry*; D016650:Fluorescein-5-isothiocyanate / Q000737:chemistry; D005453:Fluorescence; D005456:Fluorescent Dyes / Q000737:chemistry; D008856:Microscopy, Fluorescence / Q000379:methods; D053758:Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D012710:Serum Albumin, Bovine / Q000737:chemistry*; D017655:Silicon Compounds / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D017554:Carbon Compounds, Inorganic; D005456:Fluorescent Dyes; D017655:Silicon Compounds; D012710:Serum Albumin, Bovine; D018130:Diamond; D016650:Fluorescein-5-isothiocyanate; C022088:silicon carbide