Final Report Summary - NEAT BIO-ADHESIVES (A New Molecular Approach for Designing Bio-Adhesive Materials) The current mainstay of wound closure, inside the body, is suturing and stapling. Tissue adhesives, under the appropriate circumstances, may provide attractive alternatives to sutures and staples, since they can be applied more quickly, cause less pain, more economic, and may require less equipment. Tissue adhesives may obviate the need for suture removal, and can release drugs locally in a sustained manner. Our research has involved the synthesis and characterization of functional bio-glues capable of undergoing structural changes when exposed to soft tissues. We have developed our approach in a modular manner, since different properties would be required for different applications (e.g. tissue adhesive versus tissue sealant or different tissue types). This naturally leads to investigations of molecular-recognition processes within the synthetic material to control the formation of desired properties in terms of adhesiveness and structural integrity. Since the beginning of the project, significant progress has been made:1. We were able to synthesize new multi armed polymers, including polyethylene glycol and its copolymers and were able to modify them with various end groups. Pre-polymers with the selected end groups were successfully synthesized with very high yields. These polymers were fully characterized for chemical and physical properties. The polymers’ rheological profiles were assessed prior to, during and after crosslinking. Mechanical properties, including characterization of adhesiveness were also studied using porcine skin as model. Pre-polymers were viscous and sticky as planned, so as to allow injectability.2. We were able to test several administration techniques and decided to use double barrel syringe system that allows accurate administration and the best mixing prior to injection.3. We were able to characterize the cytotoxicity of several pre-polymers. We compared the performance of our system to that of commercially available formulations, namely butyl-cyanoacrylate (VetbondTM, 3M) and fibrin sealant (EvicelTM) and have noticed that cell reaction to our compounds were better or similar to commercially available glues.4. We were able to determine tissue reaction to the pre-polymers in vivo. We compared the subcutan injection of pre-polymers to rats to that of commercially available cyanoacrylate DermabondTM. We have noticed that pre-polymers did not induce any inflammation on skin and a very moderate inflammation on muscle.
