title: Diazonium salt-derived 4-(dimethylamino)phenyl groups as hydrogen donors in surface-confined radical photopolymerization for bioactive poly(2-hydroxyethyl methacrylate) grafts.
abstract: In this paper we describe a novel methodology for grafting polymers via radical photopolymerization initiated on gold surfaces by aryl layers from diazonium salt precursors. The parent 4-(dimethylamino)benzenediazonium salt was electroreduced on a gold surface to provide 4-(dimethylamino)phenyl (DMA) hydrogen donor layers; free benzophenone in solution was used as a photosensitizer to strip hydrogen from the grafted DMA. This system permitted efficient surface initiation of photopolymerization of 2-hydroxyethyl methacrylate. The resulting poly(2-hydroxyethyl methacrylate) (PHEMA) grafts were found to be very adherent to the surface as they resist total failure after being soaked in the well-known paint stripper methyl ethyl ketone. The PHEMA grafts were reacted with 1,1'-carbonyldiimidazole to yield carbamate groups that are able to react readily with amino groups from proteins. The final surface consisted of protein-functionalized PHEMA grafts where bovine serum albumin (BSA) protein is specifically linked to the grafts by covalent bonds. We used X-ray photoelectron spectroscopy to monitor the chemical changes at the gold surface all along the process from the neat gold to the end-protein-functionalized polymer grafts: the PHEMA graft thickness ranged from 7 to 27 nm, and the activation by 1,1'-carbonyldiimidazole reached 37% of the OH groups, which was sufficient for 90% surface coverage of the grafts by BSA. This work conclusively provides a new approach for bridging reactive and functional polymers to surfaces via aryl diazonium salts in a simple, fast, and efficient approach of importance in biomedical and other applications.
authors.affiliation: ITODYS, UMR CNRS 7086, Université Paris Diderot, Sorbonne Paris Cité, Paris, France.
authors.forename: Sarra
authors.initials: S
authors.lastname: Gam-Derouich
authors.forename: Aazdine
authors.initials: A
authors.lastname: Lamouri
authors.forename: Catherine
authors.initials: C
authors.lastname: Redeuilh
authors.forename: Philippe
authors.initials: P
authors.lastname: Decorse
authors.forename: François
authors.initials: F
authors.lastname: Maurel
authors.forename: Benjamin
authors.initials: B
authors.lastname: Carbonnier
authors.forename: Selim
authors.initials: S
authors.lastname: Beyazıt
authors.forename: Gorkem
authors.initials: G
authors.lastname: Yilmaz
authors.forename: Yusuf
authors.initials: Y
authors.lastname: Yagci
authors.forename: Mohamed M
authors.initials: MM
authors.lastname: Chehimi
mesh_terms: D005609:Free Radicals / Q000737:chemistry; D006859:Hydrogen / Q000737:chemistry*; D008744:Methylamines / Q000138:chemical synthesis / Q000737:chemistry*; D015394:Molecular Structure; D055668:Photochemical Processes; D011102:Polyhydroxyethyl Methacrylate / Q000138:chemical synthesis* / Q000737:chemistry; D058105:Polymerization; D012492:Salts / Q000138:chemical synthesis / Q000737:chemistry; D013499:Surface Properties
chemical_list: D005609:Free Radicals; D008744:Methylamines; D012492:Salts; D011102:Polyhydroxyethyl Methacrylate; D006859:Hydrogen