title: Albumin adsorption onto pyrolytic carbon: a molecular mechanics approach.
abstract: A number of implants of cardiac valve prosthesis, vascular prosthesis, and coronary stents present a pyrolytic carbon interface to blood. Plasma protein adsorption is essential for the hemocompatibility of the implanted devices. This work quantitatively evaluates the molecular interaction force between a biomaterial surface (pyrolytic carbon) and plasma protein (albumin) binding sites through a simplified molecular model of the interface consisting of (i) multioriented graphite microcrystallites; (ii) selected fragments of albumin; and (iii) a water environment. A number of simplifying assumptions were made in the calculation: the albumin molecule was divided into hydrophobic and hydrophilic subunits (helices); an idealized clean, nonoxidized polycrystalline graphite surface was assumed to approximate the surface of pyrolytic carbon. The interaction forces between albumin helices and pyrolytic carbon surfaces are evaluated from potential energy data. These forces are decomposed into a normal and a tangential component. The first one is calculated using a docking procedure (F( perpendicular tot MAX) = 4.16 x 10(-20) N). The second one (F( parallel)), calculated by mean of geometric models estimating the energy variation associated with the protein sliding on the material surface, varies within the range +/-9.62 x 10(-21) N. The molecular simulations were performed using the commercial software package Hyperchem 5.0 (Hyperchem, Hypercube, Canada).
authors.affiliation: Dipartimento di Bioingegneria, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy. mantero@biomed.polimi.it
authors.forename: Sara
authors.initials: S
authors.lastname: Mantero
authors.forename: Daniela
authors.initials: D
authors.lastname: Piuri
authors.forename: Franco M
authors.initials: FM
authors.lastname: Montevecchi
authors.forename: Simone
authors.initials: S
authors.lastname: Vesentini
authors.forename: Fabio
authors.initials: F
authors.lastname: Ganazzoli
authors.forename: Giuseppina
authors.initials: G
authors.lastname: Raffaini
mesh_terms: D000327:Adsorption; D000595:Amino Acid Sequence; D001665:Binding Sites; D001672:Biocompatible Materials / Q000737:chemistry*; D001807:Blood Vessel Prosthesis; D002244:Carbon / Q000737:chemistry*; D006350:Heart Valve Prosthesis; D006801:Humans; D066298:In Vitro Techniques; D008422:Materials Testing; D008958:Models, Molecular; D011487:Protein Conformation; D012709:Serum Albumin / Q000737:chemistry* / Q000493:pharmacokinetics*; D015607:Stents; D013816:Thermodynamics
chemical_list: D001672:Biocompatible Materials; D012709:Serum Albumin; C009139:pyrolytic carbon; D002244:Carbon