title: Free radical functionalization of surfaces to prevent adverse responses to biomedical devices.
abstract: Immobilizing a protein, that is fully compatible with the patient, on the surface of a biomedical device should make it possible to avoid adverse responses such as inflammation, rejection, or excessive fibrosis. A surface that strongly binds and does not denature the compatible protein is required. Hydrophilic surfaces do not induce denaturation of immobilized protein but exhibit a low binding affinity for protein. Here, we describe an energetic ion-assisted plasma process that can make any surface hydrophilic and at the same time enable it to covalently immobilize functional biological molecules. We show that the modification creates free radicals that migrate to the surface from a reservoir beneath. When they reach the surface, the radicals form covalent bonds with biomolecules. The kinetics and number densities of protein molecules in solution and free radicals in the reservoir control the time required to form a full protein monolayer that is covalently bound. The shelf life of the covalent binding capability is governed by the initial density of free radicals and the depth of the reservoir. We show that the high reactivity of the radicals renders the binding universal across all biological macromolecules. Because the free radical reservoir can be created on any solid material, this approach can be used in medical applications ranging from cardiovascular stents to heart-lung machines.
authors.affiliation: School of Physics, University of Sydney, New South Wales 2006, Australia. marcela.bilek@sydney.edu.au
authors.forename: Marcela M M
authors.initials: MM
authors.lastname: Bilek
authors.forename: Daniel V
authors.initials: DV
authors.lastname: Bax
authors.forename: Alexey
authors.initials: A
authors.lastname: Kondyurin
authors.forename: Yongbai
authors.initials: Y
authors.lastname: Yin
authors.forename: Neil J
authors.initials: NJ
authors.lastname: Nosworthy
authors.forename: Keith
authors.initials: K
authors.lastname: Fisher
authors.forename: Anna
authors.initials: A
authors.lastname: Waterhouse
authors.forename: Anthony S
authors.initials: AS
authors.lastname: Weiss
authors.forename: Cristobal G
authors.initials: CG
authors.lastname: dos Remedios
authors.forename: David R
authors.initials: DR
authors.lastname: McKenzie
mesh_terms: D004864:Equipment and Supplies / Q000009:adverse effects*; D005609:Free Radicals; D006355:Heart-Lung Machine / Q000009:adverse effects*; D006801:Humans; D011487:Protein Conformation; D011506:Proteins / Q000737:chemistry*; D015607:Stents / Q000009:adverse effects*; D013499:Surface Properties
chemical_list: D005609:Free Radicals; D011506:Proteins