“…As shown in Figure 3, the FTIR spectra of Dex, DexOx-I and DexOx-II are similar and no signal from aldehyde groups was observed. It can be due to the formation of hemiacetals 33,34 , rather than a low degree of oxidation. 35 Figure 3.FTIR spectra of: A – dextran and B – oxidized dextran-I.…”
In this paper, the authors describe a novel type of hydrogel coating prepared from the copolymer of human serum albumin and oxidized dextran. The material was designed as a hydrogel sealant for polyester (Dacron®)-based vascular grafts. Dextran was chosen as a coating material due to its anti-thrombogenic properties. Prepared hydrogels were compared with similar, already known biomaterial made from gelatine with the same cross-linking agent. Obtained hydrogels, prepared from various ratios of oxidized dextran/albumin or oxidized dextran/gelatine, showed different cross-linking densities, which caused differences in swelling, degradation rate and mechanical properties. Permeability tests confirmed the complete tightness of the hydrogel-modified prosthesis. Results showed that application of the hydrogel coating provided leakage-free prosthesis and eliminated the need of pre-clotting.
“…As shown in Figure 3, the FTIR spectra of Dex, DexOx-I and DexOx-II are similar and no signal from aldehyde groups was observed. It can be due to the formation of hemiacetals 33,34 , rather than a low degree of oxidation. 35 Figure 3.FTIR spectra of: A – dextran and B – oxidized dextran-I.…”
In this paper, the authors describe a novel type of hydrogel coating prepared from the copolymer of human serum albumin and oxidized dextran. The material was designed as a hydrogel sealant for polyester (Dacron®)-based vascular grafts. Dextran was chosen as a coating material due to its anti-thrombogenic properties. Prepared hydrogels were compared with similar, already known biomaterial made from gelatine with the same cross-linking agent. Obtained hydrogels, prepared from various ratios of oxidized dextran/albumin or oxidized dextran/gelatine, showed different cross-linking densities, which caused differences in swelling, degradation rate and mechanical properties. Permeability tests confirmed the complete tightness of the hydrogel-modified prosthesis. Results showed that application of the hydrogel coating provided leakage-free prosthesis and eliminated the need of pre-clotting.
“…37 The concentration of GRGDSPK coupled to the dextrancoated samples is lower than expected, however, considering the large number of active aldehyde groups present within the oxidized dextran macromolecules that are potentially available after oxidation. This result may be due to the presence of other types of oxidized molecular structures, for example dialdehyde and hemiacetal, as well as hemiacetal hydrates, 42,43 which may reduce the coupling efficacy of the peptide.…”
Section: Immobilization Of Grgdspk and Pf9mentioning
Segmented polyurethanes are widely used in medical devices because of their desirable physical and chemical properties and proven biocompatibility. While polyurethane is in many respects an ideal tissue scaffold, its performance is no better than other synthetic polymers, which is due in part to its surface properties. Here, we describe a method for the functionalization of polyurethane scaffolds that involves physically incorporating another polymer (poly(ethyleneimine)) such that the surface integrity and bulk properties are retained; the primary amine groups thus incorporated into the polyurethane surface enable subsequent coupling with dextran and recombinant peptides by means of reductive amination. The efficacy of the surface functionalization of a medical grade aliphatic poly(ether)urethane is verified by surface analysis (secondary ion mass spectrometry) and fluorescence and spectrophotometric assays adapted specifically for this purpose. Further assessment of the surfaces by direct cell contact and analysis of the cellular response in terms of cell coverage and morphology before and after modification with the specific peptide sequences GRGDSPK and recombinant Fibrillin-1 fragment PF9
“…Dextran is a polymer with a backbone composed of α-1,6-glycosidic linkages between glucose molecules, and aldehyde-dextran is obtained by the oxidation of dextran with periodate ( Figure 1 ). The complete oxidation of the dextran polymer promotes the formation of two aldehyde groups via a glucose molecule (an extremely high concentration of aldehyde groups) [ 18 ]. Polyaldehyde-dextran is the main structure of freshly oxidized dextran.…”
Section: Introductionmentioning
confidence: 99%
“…The reaction of single aldehyde groups and single amino groups forms very unstable Schiff´s bases and, hence, in the absence of stabilizing agents, these one-point attachments do not take place. However, incubation of this polymer at different pH values may yield other structures via the modification of vicinal aldehydes, such as aldo-enol, hydrated aldehydes, and hemiacetals [ 18 , 19 ]. These new cyclic structures are able to react with single amino groups on protein surfaces, leading to the formation of quite stable one-point attachments.…”
Immobilized enzymes have a very large region that is not in contact with the support surface and this region could be the target of new stabilization strategies. The chemical amination of these regions plus further cross-linking with aldehyde-dextran polymers is proposed here as a strategy to increase the stability of immobilized enzymes. Aldehyde-dextran is not able to react with single amino groups but it reacts very rapidly with polyaminated surfaces. Three lipases—from Thermomyces lanuginosus (TLL), Rhizomucor miehiei (RML), and Candida antarctica B (CALB)—were immobilized using interfacial adsorption on the hydrophobic octyl-Sepharose support, chemically aminated, and cross-linked. Catalytic activities remained higher than 70% with regard to unmodified conjugates. The increase in the amination degree of the lipases together with the increase in the density of aldehyde groups in the dextran-aldehyde polymer promoted a higher number of cross-links. The sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis of those conjugates demonstrates the major role of the intramolecular cross-linking on the stabilization of the enzymes. The highest stabilization was achieved by the modified RML immobilized on octyl-Sepharose, which was 250-fold more stable than the unmodified conjugate. The TLL and the CALB were 40-fold and 4-fold more stable than the unmodified conjugate.
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