title: Assemblies of concanavalin A onto carboxymethylcellulose.
abstract: The immobilization of Concanavalin A, (Con A), onto flat surfaces formed by ultrathin films of carboxymethylcellulose, CMC, silicon wafers or spin-coated poly(methyl methacrylate), (PMMA), was studied by ellipsometry, contact angle measurements and atomic force microscopy (AFM). The formation of Con A monolayer was only observed onto CMC films. The adsorption constant of Con A onto CMC films was determined as being (2.1+/-0.2) x 10(6) L mol(-1). After assembling Con A onto CMC surfaces, these became more hydrophobic, indicating a molecular orientation of Con A hydrophilic residues to the polysaccharide and Con A hydrophobic residues to the air. The affinity of Con A for hydroxyl rich silicon surfaces or for more hydrophobic PMMA films was very weak, evidencing that nonspecific interactions play a marginal role. For comparison, the immobilization of Con A onto hybrid particles of PMMA/CMC was investigated by means of UV-spectrophotometry. Such particles carry CMC chains attached to the surface, as evidenced by mean zeta potential value of -40 mV. The adsorption constant determined for Con A onto PMMA/CMC particles was one order of magnitude smaller than that found for Con A onto CMC films. This finding indicates that the substrate geometry might influence the molecular arrangement of sugar residues on the surface, consequently affecting the sugar-Con A interaction (cluster effect).
authors.affiliation: Instituto de Química, Universidade de São Paulo, Av. Prof. Lineu Prestes 748, 05508-900, São Paulo, Brazil.
authors.forename: Lizandra B R
authors.initials: LB
authors.lastname: Castro
authors.forename: Denise F S
authors.initials: DF
authors.lastname: Petri
mesh_terms: D002266:Carboxymethylcellulose Sodium / Q000737:chemistry*; D003208:Concanavalin A / Q000737:chemistry*; D018625:Microscopy, Atomic Force; D036103:Nanotechnology; D013056:Spectrophotometry, Ultraviolet
chemical_list: D003208:Concanavalin A; D002266:Carboxymethylcellulose Sodium