Polyethylene glycol-albumin/fibrin interpenetrating polymer networks with adaptable enzymatic degradation for tissue engineering applications

A new series of polyethylene glycol-albumin/Fibrin interpenetrating polymer networks (PEG-BSA/Fb IPNs) combining a fibrin gel with a co-network of polyethylene glycol and serum albumin has been developed in order to study the enzymatic degradation of such architectures combining protein and synthetic polymer partners. BSA provides biodegradability thank to its many segments cleavable by enzymes while PEG ensures material resistance (shape preservation, mechanical moduli,...). Previous the degradation study of these easily manipulable PEG-BSA/Fb IPNs, it was shown that each partner (fibrin, PEG and BSA) contributes to the elastic modulus value which is only possible in an IPN architecture where the different polymer partners form a continuous phase in the whole material. The homogeneous protein distribution in the materials was also confirmed by confocal microscopy. Then, their biodegradability was studied by combining three complementary characterizations: on the one hand, absorbance of the hydrolytic enzyme solution in which they were immersed to quantify the proportion of protein fragment extracted and, on the other hand, viscoelastic moduli of the hydrogels after immersion in the same enzyme to evaluate their mechanical resistance, and finally, MEB imaging to check the hydrolysis homogeneity. The proteolytic enzyme degrades quickly IPNs containing less than 3 wt% PEG while other IPNs remain resistant to proteolysis over long periods, although their viscoelastic properties are reduced by 70% and morphology at the microscopic level changed in a few hours. The degradation rate of these materials is thus easily tunable by composition adjustment. (C) 2018 Elsevier Ltd. All rights reserved.