Preparation of UV-curable polyurethane-acrylate based multifunctional bone adhesives and their usage for sternal closure

Sternal closure is a re-closure of the opened thorax after open heart surgery. Currently, mechanical methods (steel wire) are used for sternal closure and high mortality rates are observed due to not being closed properly of sternum. The basis of the high number of deaths is due to the disadvantages of mechanical methods and infections. Within the scope of the thesis, an adhesive formulation was created to eliminate these problems. In this context, a biocompatible, antibacterial, UV-curable and injectable adhesive have been developed with fast and strong adhesive properties including biomimetic design. The formulation was formed from two-component UV-curable polyurethane-acrylate system. The first component is an injectable prepolymer comprising double bonded open ends. The second component consists of UV-curing dopamine methacrylamide and curing agent. 27 adhesive formulations with different monomer ratios were first synthesized in the form of pre-polyurethane. β-cyclodextrin, protein (gelatin (GEL), sericin (SER) and collagen (COL)) and polyethylene glycol (P200/P400/P600) were used as polyol sources and 4,4-methylenebis (cyclohexyl isocyanate) (HMDI) was used as isocyanate source in pre-polyurethane synthesis. Pre-polyurethane structures were converted to double bond functional pre-polymers with 2-isocyanatoethyl methacrylate from the -OH ends and gentamycin was added to provide antibacterial character to the structure. Pre-polymers were cured by UV exposure with dopamine methacrylamide and photoinitiator for 5-15 min. The final adhesives were characterized structurally, thermally and morphologically. According to the results of the adhesion strength of polyurethane-acrylates, 3 formulations (HMDI-GEL-P400-20-AC, HMDI-SER-P200-20-AC, HMDI-COL-P600-20-AC) were selected and biodegradability, gentamicin release, antibacterial property, protein adsorption and in vitro biocompatibility tests were performed to the formulations. Then, according to in vitro results, HMDI-SER-P200-20-AC formulation was selected and in vivo biocompatibility and sternal closure tests were performed. As a result, highly adhesive, rapid curing, antibacterial and biocompatible adhesive formulations have been developed and used in sternal closure.