Laser-activated solid protein solder for nerve repair: In vitro studies oftensile strength and solder/tissue temperature

Laser-activated solid protein solder strips have been developed for periphe ral nerve repair. Indocyanine green dye added to the solder strongly absorb s diode wavelengths (similar to 800 nm) and causes localised heating and co agulation of the albumin protein solder. The protein strengthens the tissue join, particularly during the acute healing phase postoperative, while shi elding the underlying axons from excessive thermal damage. In this investigation of the solid protein solder technique for nerve repai r, the effect of laser irradiance on weld strength and solder and tissue te mperature were studied. The tensile strength of repaired nerves rose steadi ly with increased irradiance reaching a maximum of 105 +/- 10 N/cm(2) at 12 .7 W/cm(2). At higher irradiances, tensile strength fell. The maximum tempe rature reached at the solder surface and at the solder/nerve interface, mea sured using a non-contact fibre optic radiometer and thermocouple, respecti vely, also rose steadily with laser irradiance. At 12.7 W/cm(2), the temper atures reached at the surface and it the interface were 88 +/- 5 degrees C and 71 +/- 4 degrees C, respectively. This in vitro investigation demonstrates the feasibility of the laser-activ ated solid protein solder strips for peripheral nerve repair. The laser irr adiance and the corresponding solder surface temperature for optimal tensil e strength have been identified.