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Hydrogels derived from synthetic polymers have been previously engineered to degrade under the activity of matrix metalloproteinases (MMPs). It is believed that these systems can act as extracellular-matrix (ECM) equivalents mimicking the degradation and remodeling of the ECM through the activity of cell-secreted enzymes. In this study, MMP-sensitive hydrogels derived from dextran were developed. In order to avoid the incorporation of hydrolyzable esters often introduced in dextran modification strategies, the polysaccharide was modified with p-maleimidophenyl isocyanate (PMPI) thereby introducing maleimide functionalities in the backbone and resulting in dextran derivatized with p-maleimidophenyl isocyanate (Dex-PMPI). This strategy was favored to separate out the effects of random hydrolysis and enzymatic digestion in the degradation of the dextran hydrogels. A peptide cross-linker, derived from collagen and susceptible to gelatinase A (MMP-2) digestion, was synthesized with bifunctional cysteine termini and used to cross-link the Dex-PMPI. These hydrogels were found to be hydrolytically stable for more than 200 days yet degraded either within 30 h when exposed to bacterial collagenase or within 16 days when exposed to human MMP-2, demonstrating enzymatic-mediated digestion of the peptide cross-links. Further modification of the cross-linked hydrogels with laminin-derived peptides enhanced cell adhesion and survival, demonstrating the potential of these materials for use in tissue engineering applications.

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This article presents the results of a study that analyses students' historical narratives of the nation in relation to historical consciousness and how their sense of self-identification with groups affects their narrative structure and orientation. This study was conducted with French Canadian students registered in two high schools (n=58) and one university (n=18) in Ottawa, the federal capital of Canada. I found that a strong sense of identification leads young people to construct more engaging and militant stories of the collective past, with greater historical appropriation (using the collective 'we') and a sense of continuity with past actualities. I then discuss the implications of this study for research on the narrative competence of historical consciousness and what history education might do in school to promote historical consciousness in Canada.