Laser tissue welding of dura mater and peripheral nerves: a scanning electron microscopy study

In order to elucidate the mechanism of tissue welding, scanning electron microscopy (SEM) was used to investigate the ultrastructural changes on the surface of dura mater and peripheral nerves after CO2 laser welding. The dura mater and the epineurium of the nerves was welded with a CO2 laser at 100 mW with pulses of 1.0 s (spot size 320 microns), both with and without additional use of a protein solder (egg white). The specimens were immediately examined using SEM. The laser tissue bonding mechanism is collagen-to-collagen attachment. After laser irradiation, the collagen fibrils are swollen, densely packed, and fused together. When a protein solder is used, the coagulated solder forms a solid bridge between the tissue edges, which is melted on and between the collagen fibrils. Laser welds in dura mater and peripheral nerves are the result of collagen-to-collagen bonding. In solder-assisted laser welds, the tissue connection is made by an internal and an external matrix of coagulated solder