Viscoelastic adhesive mechanics of aldehyde-mediated soft tissue sealants

Soft tissue sealants generally sacrifice adhesive strength for biocompatibility, motivating the development of materials which interact with tissue to a predictable and controllable extent. Crosslinked hydrogels comprising aminated star polyethylene glycol and high molecular weight dextran aldehyde polymers (PEG:dextran) display aldehyde-mediated adhesion and readily tunable reactivity with soft tissue ex-vivo. Evaluation of PEG:dextran compositional variants revealed that the burst pressure of repaired intestinal wounds and the extent of material-induced tissue deformation both increase nonlinearly with formulation aldehyde content and are consistently within the desired range established by traditional sealants. Adhesive test elements featuring PEG:dextran and intestinal tissue exhibited considerable viscoelasticity, prompting use of a standard linear solid (SLS) model to describe adhesive mechanics. Model elements were accurately represented as continuous functions of PEG:dextran chemistry, facilitating prediction of adhesive mechanics across the examined range of compositional formulations. SLS models of traditional sealants were also constructed to allow general correlative analyses between viscoelastic adhesive mechanics and metrics of sealant performance. Linear correlation of equilibrium SLS stiffness to sealant-induced tissue deformation indicates that dense adhesive cross-linking restricts tissue expansion, while correlation of instantaneous SLS stiffness to burst pressure suggests that the adhesive stress relaxation capacity of PEG:dextran enhances their overall performance relative to traditional sealants. (c) 2008 Elsevier Ltd. All rights reserved.