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).

Lectins and/or xyloglucans/alginate layers as supports for immobilization of dengue virus particles

“…2a), for scan areas of 3 m × 3 m and 2.5 m × 2.5 m, respectively. Similar morphological features have been observed for ConA adsorbed onto carboxymethyl cellulose (CMC) [4,5] or cashew gum [10] films. Mean thickness values determined for ConA films when the polysaccharide surface was negatively charged as CMC or XG-ALG mix layers amounted to (4 ± 1) nm.…”

“…Because the native SiO 2 layer is very thin, its n was set as 1.462 [22] and the mean thickness value D was calculated for 50 Si wafers as (1.9 ± 0.1) nm. The indices of refraction for polysaccharides, lectins and viruses were set as 1.50 [23], 1.52 [5] and 1.50, respectively, and just the layer thickness was calculated. One must be aware that ellipsometry yields the mean thickness based on a model, which considers the adsorbed layer as a homogeneous isotropic smooth layer.…”

“…These derivatives are potential supports for biomedical applications due to their biocompatibility and their role in many recognition processes. Complex and variable structures, molecular recognition and specific binding between polysaccharides and proteins open a large field for biosensors and bioassays design [4][5][6][7][8][9][10][11][12][13][14].…”

Filmes ultrafinos de ésteres de celulose: preparo, caracterização e imobilização de proteínas

“…Estas características são confirmadas pelos valores de rugosidade média obtidos para os filmes de CAB e CMCAB de 0,20 ± 0,02 e 0,30 ± 0,03 nm, respectivamente, os quais não diferem muito da rugosidade média do substrato 0,10 ± 0,01 nm. 26,27 Os valores dos ângulos de contato determinados para filmes de CAB e CMCAB θ a = 54 ± 1º e θ a = 60 ± 1º, respectivamente, evidenciaram que a molhabilidade dessas superfícies diminuiu, pois os valores de θ a aumentaram em relação ao SiO 2 , 26,27 θ a = 5 ± 1º. Portanto, a provável orientação do grupo butirato para o ar tornou as superfícies mais hidrofóbicas.…”

Adsorption behavior and activity of horseradish peroxidase onto polysaccharide-decorated particles

“…PMMA/CMC hybrid particles are formed by PMMA core and CMC as outermost layers [15][16][17], providing hydrophilic carbohydrate rich surfaces. Such particles are excellent substrates for the adsorption of metallic ions [18] and lectins [19,20]. Particle characterization has been performed before and after HRP adsorption by means of dynamic light scattering, zeta potential measurements, scanning electron microscopy.…”