Effect of functionalized PHEMA micro- and nano-particles on the viscoelastic properties of fibrin-agarose biomaterials

Two types of PHEMA-based particles, exhibiting either carboxyl or tertiary ammine functional groups, were incorporated to fibrin-agarose (FA) hydrogels, and the effect of the addition of these synthetic particles on the viscoelastic and microstructural properties of the biomaterials was evaluated. Experimental results indicated that the incorporation of both types of polymeric particles to FA scaffolds was able to improve the biomechanical properties of the biomaterials under steady state and oscillatory shear stresses, resulting in scaffolds characterized by higher values of the storage, loss, and shear moduli. In addition, the microstructural evaluation of the scaffolds showed that the nanoparticles exhibiting carboxyl functional groups were homogeneously distributed across the fibrous network of the hydrogels. The addition of both types of artificial polymeric particles was able to enhance the viscoelastic properties of the FA hydrogels, allowing the biomaterials to reach levels of mechanical consistency under shear stresses in the same range of some human native soft tissues, which could allow these biomaterials to be used as scaffolds for new tissue engineering applications.Peer ReviewedPostprint (author's final draft

Etude des O-carboxyméthylcelluloses à degré de substitution variable. I : Préparation et caractérisation des produits

International audienc

Étude des O-carboxyméthylcelluloses à degré de substitution variable. I. — Préparation et caractérisation des produits

Une nouvelle méthode de préparation des O-carboxyméthylcelluloses à DS variable est décrite, conduisant à des produits bien définis de DS compris entre 0,4 et 2,84.Une étude morphologique par viscosité de ces produits permet d'attribuer aux CMC de DS > 0,7 en solution aqueuse, une forme de bâtonnet rigide de 10 à 12 Å de diamètre

Can immunoglobulin C(H)1 constant region domain modulate antigen binding affinity of antibodies?

International audienceAlthough the switch process is frequently associated with affinity maturation, the constant region is not assumed to play a role in Ag-Ab binding. In the present work, we demonstrate that two clonally related human monoclonal Igs sharing identical V(H) and V(L) sequences, but expressing different isotypes (IgA1kappa(PER) and IgG1kappa(PER)), bind tubulin with significantly different affinities. This difference was mainly accounted for by a disparity in the association rate constants. These results suggest that affinity maturation of this clone could be achieved through class switching in the absence of further somatic mutations. Since the differences observed were found at the Fab level, they also suggest a role for the C(H)1 domain in structuring the Ag-binding site into a more kinetically competent form