Synthetic polymer-tissue adhesion using an ultrasonic scalpel

Interface phenomena such as encapsulation and formation of dead space around implanted biomaterials lower biomaterial performance. To advance tissue adhesive technology, understanding the interactions between tissue (collagen) and polymer is indispensable. Adhesion between tissue and polymer was studied using an ultrasonically activated scalpel (UAS).

The Harmonic Scalpel was used as an ultrasonically activated scalpel for polymer and tissue adhesion. A piece of porcine aorta and a polymeric film were layered and placed between the blades of the Harmonic Scalpel. Then the samples were gripped with 20 kgf of force for 1-10 s to adhere the porcine aorta and polymeric films. The adhesion was characterized by macro- and microscopic observation, thermographic analysis, and measurement of bonding strength, static contact angle (SCA), and surface properties.

Cellulose, vinylon, polyethylene terephthalate, nylon, and Pellethane could be bonded to the aorta. Bonding was not observed for the polyethylene, polypropylene, polyvinyl chloride, or polytetrafluoroethylene. This suggests that the existence of functional groups such as hydroxyl, carbonyl, carboxyl, and amide groups in the polymer structure are key factors in adhesion. Harmonic Scalpel modification of the polyethylene surface during corona discharge treatment further indicated that the functional groups of the polymers are one of the essential factors for tissue adhesion. The temperatures of adhesion were 90-150 °C for the polymers, and the melting temperatures (Tm) were 193-306 °C. This suggests that adhesion was formed by the interaction between the melted polymer surface and the tissue collagen.

Both polar functional groups and adequate thermal characteristics are necessary for polymers to bond with tissues. These findings should be useful for the development of novel polymers that can be bonded to living tissues with UAS treatment, which can be applied for endoscopic surgery.