Cross-linking and characterisation of gelatin matrices for biomedical applications.
Cross-linking of gelatin A and B with N,N-(3-dimethylaminopropyl)-N'-ethyl-carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) was optimised by varying the NHS/EDC molar ratio at constant EDC concentration. Native and cross-linked gelatin gels were characterised using the degree of swelling, the number of free amine groups, the phase transition temperature, and titration of the carboxylic acid residues. The cross-linking reaction was most efficient at a NHS to EDC molar ratio of 0.2. At higher NHS/EDC molar ratios, the reaction of EDC with NHS becomes more pronounced, thereby reducing the effective amount of EDC for cross-linking. Swelling measurements of cross-linked gelatin gels gave deviating results when no NHS was used, which was explained by heterogeneous localisation of cross-links in the gelatin gel. The incorporation of undesired compounds into the gelatin gels during the cross-linking reaction was not observed. At optimal NHS to EDC molar ratio, gelatin A and B were cross-linked using increasing EDC/COOHgelatin molar ratios. A range of samples varying from very low cross-link density to very high cross-link density (at high EDC/COOHgelatin) was obtained. Stability of the gels is enhanced with increasing cross-link density, but a minimal cross-link density is required to obtain gelatin gels which are stable at 40 degrees C.
Kuijpers
A J
AJ
Department of Chemical Technology, Institute of Biomedical Technology, University of Twente, Enschede, The Netherlands.
Engbers
G H
GH
Krijgsveld
J
J
Zaat
S A
SA
Dankert
J
J
Feijen
J
J
D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry*; D002417:Cattle; D003432:Cross-Linking Reagents; D005022:Ethyldimethylaminopropyl Carbodiimide; D005780:Gelatin / Q000737:chemistry*; D005782:Gels; D008422:Materials Testing; D008956:Models, Chemical; D013388:Succinimides; D013552:Swine
D001672:Biocompatible Materials; D003432:Cross-Linking Reagents; D005782:Gels; D013388:Succinimides; D005780:Gelatin; C001426:N-hydroxysuccinimide; D005022:Ethyldimethylaminopropyl Carbodiimide