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Structural analysis of dextran-based hydrogels obtained chemoenzymatically
Ferreira, L.; Figueiredo, M. M.; Gil, M. H.; Ramos, M. A.This work reports the results of structural analysis in novel dextran-acrylate (dexT70-VA) hydrogels generated chemoenzymatically. Porous structure as well as hydrogel surface and interior morphologies were evaluated by mercury intrusion porosimetry (MIP), nitrogen adsorption (NA), and scanning electron microscopy (SEM) analyses, as a function of the degree of substitution (DS), and initial water content used i...
Influence of different silica derivatives in the immobilization and stabilizati...
Ferreira, L.; Ramos, M. A.; Dordick, J. S.; Gil, M. H.Alcalase 2T, a commercial preparation of Subtilisin Carlsberg, was covalent immobilized onto physiochemically characterized silica supports. The effect of mean pore diameter and surface chemistry on enzyme activity in the hydrolysis of casein has been examined. Two sets of chemically distinct silica supports were used presenting terminal amino (SAPTES) or hydroxyl groups (STESPM-pHEMA). The percentage of immobi...
Exquisite Regioselectivity and Increased Transesterification Activity of an Imm...
Ferreira, Lino; Ramos, M. A.; Gil, Maria Helena; Dordick, Jonathan S.Commercially available proteases and lipases were screened for their ability to acylate regioselectively sucrose with divinyladipate either in pyridine or dimethylformamide (DMF). The protease (EC 3.4.21.62) from Bacillus subtilis (Proleather FG-F) exhibited the highest conversion (100% in 24 h of reaction in DMF) yielding sucrose 2- O-vinyladipate as main product. The enzyme preference for a secondary hydroxyl...
Physical and chemical characterisation of some silicas and silica derivatives
Ramos, M. A.; Gil, M. H.; Schacht, E.; Matthys, G.; Mondelaers, W.; Figueiredo, M. M.An extensive study of four types of porous silica supports has been performed, with particular emphasis on their physical and morphological characteristics. These silicas were modified by reacting the surface silanol groups present with either 3-(trimethoxysilyl)propylmethacrylate or 3-glycidoxypropyltrimethoxysilane or 3-aminopropyltriethoxysilane, to produce derivatives with suitable functional groups for fur...
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