title: Covalent immobilisation of VEGF on plasma-coated electrospun scaffolds for tissue engineering applications.
abstract: Recent findings in the field of biomaterials and tissue engineering provide evidence that surface immobilised growth factors display enhanced stability and induce prolonged function. Cell response can be regulated by material properties and at the site of interest. To this end, we developed scaffolds with covalently bound vascular endothelial growth factor (VEGF) and evaluated their mitogenic effect on endothelial cells in vitro. Nano- (254±133 nm) or micro-fibrous (4.0±0.4 μm) poly(ɛ-caprolactone) (PCL) non-wovens were produced by electrospinning and coated in a radio frequency (RF) plasma process to induce an oxygen functional hydrocarbon layer. Implemented carboxylic acid groups were converted into amine-reactive esters and covalently coupled to VEGF by forming stable amide bonds (standard EDC/NHS chemistry). Substrates were analysed by X-ray photoelectron spectroscopy (XPS), enzyme-linked immuno-assays (ELISA) and immunohistochemistry (anti-VEGF antibody and VEGF-R2 binding). Depending on the reaction conditions, immobilised VEGF was present at 127±47 ng to 941±199 ng per substrate (6mm diameter; concentrations of 4.5 ng mm(-2) or 33.3 ng mm(-2), respectively). Immunohistochemistry provided evidence for biological integrity of immobilised VEGF. Endothelial cell number of primary endothelial cells or immortalised endothelial cells were significantly enhanced on VEGF-functionalised scaffolds compared to native PCL scaffolds. This indicates a sustained activity of immobilised VEGF over a culture period of nine days. We present a versatile method for the fabrication of growth factor-loaded scaffolds at specific concentrations.
authors.affiliation: Empa, Swiss Federal Institutes for Materials Science and Technology, Lerchenfeldstrasse 5, 9014 St. Gallen, Switzerland. Electronic address: a.guex@imperial.ac.uk.
authors.forename: A G
authors.initials: AG
authors.lastname: Guex
authors.affiliation: Empa, Swiss Federal Institutes for Materials Science and Technology, Lerchenfeldstrasse 5, 9014 St. Gallen, Switzerland. Electronic address: dirk.hegemann@empa.ch.
authors.forename: D
authors.initials: D
authors.lastname: Hegemann
authors.affiliation: Cardiology, University of Fribourg, Chemin du Musée 5, 1700 Fribourg, Switzerland. Electronic address: marie-noelle.giraud@unifr.ch.
authors.forename: M N
authors.initials: MN
authors.lastname: Giraud
authors.affiliation: Department of Cardiovascular Surgery, Inselspital, Berne University Hospital and University of Berne, Murtenstrasse 35, 3010 Bern, Switzerland. Electronic address: hendrik.tevaearai@insel.ch.
authors.forename: H T
authors.initials: HT
authors.lastname: Tevaearai
authors.affiliation: Empa, Swiss Federal Institutes for Materials Science and Technology, Lerchenfeldstrasse 5, 9014 St. Gallen, Switzerland. Electronic address: ana.maria.buehlmann@gmail.com.
authors.forename: A M
authors.initials: AM
authors.lastname: Popa
authors.affiliation: Empa, Swiss Federal Institutes for Materials Science and Technology, Lerchenfeldstrasse 5, 9014 St. Gallen, Switzerland. Electronic address: rene.rossi@empa.ch.
authors.forename: R M
authors.initials: RM
authors.lastname: Rossi
authors.affiliation: Empa, Swiss Federal Institutes for Materials Science and Technology, Lerchenfeldstrasse 5, 9014 St. Gallen, Switzerland. Electronic address: giuseppino.fortunato@empa.ch.
authors.forename: G
authors.initials: G
authors.lastname: Fortunato
mesh_terms: D010949:Plasma / Q000737:chemistry; D011091:Polyesters / Q000737:chemistry*; D023822:Tissue Engineering / Q000379:methods*; D054457:Tissue Scaffolds / Q000737:chemistry*; D042461:Vascular Endothelial Growth Factor A / Q000737:chemistry*
chemical_list: D011091:Polyesters; D042461:Vascular Endothelial Growth Factor A; C016240:polycaprolactone
keywords: Electrospinning; Plasma polymerization; Tissue engineering; VEGF