title: Surface functionalization of thin-film diamond for highly stable and selective biological interfaces.
abstract: Carbon is an extremely versatile family of materials with a wide range of mechanical, optical, and mechanical properties, but many similarities in surface chemistry. As one of the most chemically stable materials known, carbon provides an outstanding platform for the development of highly tunable molecular and biomolecular interfaces. Photochemical grafting of alkenes has emerged as an attractive method for functionalizing surfaces of diamond, but many aspects of the surface chemistry and impact on biological recognition processes remain unexplored. Here we report investigations of the interaction of functionalized diamond surfaces with proteins and biological cells using X-ray photoelectron spectroscopy (XPS), atomic force microscopy, and fluorescence methods. XPS data show that functionalization of diamond with short ethylene glycol oligomers reduces the nonspecific binding of fibrinogen below the detection limit of XPS, estimated as > 97% reduction over H-terminated diamond. Measurements of different forms of diamond with different roughness are used to explore the influence of roughness on nonspecific binding onto H-terminated and ethylene glycol (EG)-terminated surfaces. Finally, we use XPS to characterize the chemical stability of Escherichia coli K12 antibodies on the surfaces of diamond and amine-functionalized glass. Our results show that antibody-modified diamond surfaces exhibit increased stability in XPS and that this is accompanied by retention of biological activity in cell-capture measurements. Our results demonstrate that surface chemistry on diamond and other carbon-based materials provides an excellent platform for biomolecular interfaces with high stability and high selectivity.
authors.affiliation: Department of Chemistry, University of Wisconsin at Madison, 1101 University Avenue, Madison, WI 53706, USA.
authors.forename: Courtney
authors.initials: C
authors.lastname: Stavis
authors.forename: Tami Lasseter
authors.initials: TL
authors.lastname: Clare
authors.forename: James E
authors.initials: JE
authors.lastname: Butler
authors.forename: Adarsh D
authors.initials: AD
authors.lastname: Radadia
authors.forename: Rogan
authors.initials: R
authors.lastname: Carr
authors.forename: Hongjun
authors.initials: H
authors.lastname: Zeng
authors.forename: William P
authors.initials: WP
authors.lastname: King
authors.forename: John A
authors.initials: JA
authors.lastname: Carlisle
authors.forename: Aleksei
authors.initials: A
authors.lastname: Aksimentiev
authors.forename: Rashid
authors.initials: R
authors.lastname: Bashir
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Hamers
mesh_terms: D000907:Antibodies, Bacterial / Q000737:chemistry*; D001360:Avidin / Q000737:chemistry; D002627:Chemistry, Physical / Q000379:methods*; D018130:Diamond / Q000737:chemistry*; D048168:Escherichia coli K12 / Q000276:immunology; D019855:Ethylene Glycol; D005340:Fibrinogen / Q000737:chemistry*; D005453:Fluorescence; D018625:Microscopy, Atomic Force / Q000379:methods*; D056951:Photoelectron Spectroscopy / Q000379:methods*; D011485:Protein Binding; D013499:Surface Properties
chemical_list: D000907:Antibodies, Bacterial; D001360:Avidin; D018130:Diamond; D005340:Fibrinogen; D019855:Ethylene Glycol