title: Comparison of the density of proteins and peptides grafted on silane layers and polyelectrolyte multilayers.
abstract: Immobilized proteins or peptides are of critical importance for applications such as biosensing or cell culture. We analyze the structure of layers of a large variety of proteins and peptides, grafted on silicon substrates by different routes differing in the nature of the intermediate layer linking the biomolecules to the substrate, either a silane monolayer, or a polyelectrolyte multilayer made from synthetic or natural polymers. The structural analysis is essentially performed by X-ray reflectometry, which proves to be an efficient methodology not requiring the use of tagged biomolecules, capable of evaluating consistently the amount of grafted biomolecules per surface area with estimated precisions ranging from 10 to 20%. The study provides a quantitative basis for selecting one among a series of well-proofed and sturdy grafting methodologies and underlines the potential of XRR for assessing the amount of grafted biomacromolecules without requiring the expensive tagging of molecules. Our results also show that, for the coupling route resting on synthetic polyelectrolytes, the grafting density is significantly lower than for direct coupling over a silane layer. In contrast, when performed over a cushion based on polysaccharides, the grafting density is well above the values found for a dense layer grafted on a silane monolayer, indicating partial penetration and swelling of the polysaccharide cushion.
authors.affiliation: Bio and Soft Matter, Institute of Condensed Matter and Nanosciences, Université Catholique de Louvain , Croix du Sud 1 L7.04.02, 1348 Louvain-la-Neuve, Belgium.
authors.forename: Olivier
authors.initials: O
authors.lastname: Deschaume
authors.forename: Delphine
authors.initials: D
authors.lastname: Magnin
authors.forename: Zhe A
authors.initials: ZA
authors.lastname: Cheng
authors.forename: Colette
authors.initials: C
authors.lastname: Douchamps
authors.forename: Pierre
authors.initials: P
authors.lastname: Labbé
authors.forename: Sami
authors.initials: S
authors.lastname: Yunus
authors.forename: Marie-Christine
authors.initials: MC
authors.lastname: Durrieu
authors.forename: Bernard
authors.initials: B
authors.lastname: Nysten
authors.forename: Karine
authors.initials: K
authors.lastname: Glinel
authors.forename: Sophie
authors.initials: S
authors.lastname: Demoustier-Champagne
authors.forename: Alain M
authors.initials: AM
authors.lastname: Jonas
mesh_terms: D010455:Peptides / Q000737:chemistry*; D011134:Polysaccharides / Q000737:chemistry; D011506:Proteins / Q000737:chemistry*; D012821:Silanes / Q000737:chemistry*; D012825:Silicon / Q000737:chemistry; D013499:Surface Properties
chemical_list: D010455:Peptides; D011134:Polysaccharides; D011506:Proteins; D012821:Silanes; D012825:Silicon